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 I
 
 THE DIAGNOSIS OF 
 SMALLPOX 
 
 \N^ \l J 
 
 r. F. R: 
 
 RBY 
 ICKETTS 
 
 M.D., B.Sc. (Lend.), M.R.C.P., D.P.H. 
 
 Medical Superintendent of the Smallpox Hospitals and of the River 
 
 Ambulance Service of the Metropolitan Asylums Board 
 
 ILLUSTRATED FROM PHOTOGRAPHS BY 
 
 J. B. BYLES 
 
 M.H., B.C. (Cantab.). F.R.C.S. Eng., D.P.H. 
 
 Senior Assistant Medical Officer at the Smallpox Hospitals of the 
 Metropolitan Asylums Board 
 
 WITH 12 COLOURED PLATES, IIO BLACK-AND-WHITE 
 PLATES, AND 14 CHARTS 
 
 NEW YORK 
 FUNK AND WAGNALLS COMPANY 
 
 1910
 
 ? 
 

 
 PREFACE 
 
 IT is ten years or more since the author conceived 
 the notion of writing this book. He was deterred 
 by the consideration that it would have but little 
 value unless adequately illustrated, and to the 
 execution of that part of the task he did not see 
 the way. Some years later the project was revived 
 at the suggestion of Mr. E. L. Meinertzhagen, 
 chairman of sub- committee of the metropolitan 
 smallpox-hospitals, who urged the author to under- 
 take the preparation of the work and secured the 
 co-operation of the Metropolitan Asylums Board. 
 It is owing to the facilities extended to us by the 
 Board that the realisation of the project has become 
 possible. 
 
 As to the importance of the subject and the 
 need for its exhaustive treatment there will probably 
 not be two opinions, though there may be several 
 opinions about the value of this result. Perhaps 
 the most noteworthy difference from the teaching 
 of previous writers on the subject resides in the 
 importance attributed to the distribution of the 
 eruption : a diagnostic criterion which has been 
 lifted from a subordinate to a leading position. 
 This doctrine may sound more novel elsewhere 

 
 vi PREFACE 
 
 than in London, where it has been taught by the 
 author to his colleagues and pupils for the last 
 fifteen years. It has been abundantly justified by 
 the experience gained in the diagnosis of many 
 thousands of cases. 
 
 In spite of the number of illustrations, there 
 are still some gaps which remain unfilled or are 
 filled imperfectly. This circumstance is due to the 
 fact that while the work has been in preparation 
 smallpox has not attained epidemic proportions in 
 London, and certain subjects of infrequent occur- 
 rence have not been available for record. Thus 
 it would have been an advantage to present some 
 further illustrations of haemorrhagic or toxic small- 
 pox. 
 
 In compensation, we are so fortunate as to have 
 several of the illustrations in colour. These, we 
 think, will be of particular value in conveying 
 accurate and life-like impressions of the subjects 
 treated. It may be of interest to state that, with 
 the exception of the frontispiece, these colour- plates 
 are produced from triple negatives obtained by the 
 Sanger - Shepherd process of colour - photography. 
 We believe this to be the first medical work which 
 has been freely illustrated by means of colour- 
 photographs taken from life. Very obvious is the 
 advantage in point of fidelity over the coloured 
 illustrations of medical subjects ordinarily obtained 
 by means of water-colour drawings. 
 
 Among the half - tone plates are a number of 
 stereoscopic subjects. Readers are advised to
 
 PREFACE vii 
 
 examine these through one of the cheap pocket- 
 stereoscopes which may now be obtained at many 
 opticians'. In spite of the fact that the cross- 
 hatching of the process - screen becomes unduly 
 obvious when magnified by the stereoscope, con- 
 siderable assistance will be derived from its use. 
 But these stereoscopic prints are, of course, by no 
 means valueless when viewed by the naked eye. 
 
 With one exception (Plate XXXIIL, Fig. 2), all 
 the prints are from photographs taken of patients 
 with smallpox or of patients whose illness had 
 been mistaken for smallpox. For the photographic 
 original of Plate xxxni., Fig. 2, we are indebted to 
 Dr. A. F. Cameron, of the South-Eastern Metro- 
 politan Fever Hospital. 
 
 We take this opportunity of expressing our 
 great indebtedness to Dr. Frederick Thomson, 
 medical superintendent of the North-Eastern Metro- 
 politan Fever Hospital, and at one time acting 
 medical officer of the Metropolitan River- Ambulance 
 Service for smallpox. To his co-operation we owe 
 opportunities of securing records of several of the 
 cases of mistaken diagnosis illustrated in the plates 
 and of some cases of smallpox which, without his 
 assistance, would have come under our notice too 
 late to be of value. 
 
 T. F. R. 
 J. B. B. 
 
 October, 1908.
 
 CONTENTS 
 
 CHAPTER PAOB 
 
 I. INTRODUCTORY ....... 1 
 
 II. DISTRIBUTION ........ 6 
 
 III. DISTRIBUTION (continued) . . . . . 14 
 
 IV. DIAGNOSIS BY DISTRIBUTION 21 
 
 V. THE LESION 26 
 
 VI. THE ERUPTION AND THE ERUPTIVE FEVER . . 33 
 VII. MODIFIED SMALLPOX ...... 43 
 
 VIII. SECONDARY CHARACTERISTICS OF THE ERUPTION . 51 
 
 IX. THE TOX/EMIC FEVER 58 
 
 X. TOX.EMIC RASHES 66 
 
 X I. ELEMORRHAGIC SYMPTOMS 73 
 
 XII. H^MORRHAGIC OR TOXIC SMALLPOX . . . 85 
 
 XIII. H.EMORRHAGIC OR Toxic SMALLPOX (concluded) . 95 
 
 XIV. ERYTHEMATA : SIMPLE AND SYMPTOMATIC . . 104 
 XV. CHICKENPOX 117 
 
 XVI. SYPHILIS VACCINIA 125 
 
 XVII. DERMATITIS PUSTULAR DERMATOSES . . . 132 
 
 XVIII. VACCINATION AS A FACTOR IN DIAGNOSIS . . 141 
 
 INDEX . - .149 
 
 2141
 
 LIST OF PLATES 
 
 FRONTISPIECE (in colour) : 
 
 Histological section of a variolous lesion. 
 
 PLATE FACING PAGE 
 
 I. Irritation-patches . .12 
 
 II. Irritation-patches . . 
 
 III. Distribution influenced by attire . . ,, 
 
 IV. Fig. 1, Garter mark; Fig. 2, Friction of the trouser- 
 
 end ..... > 
 
 V. Fig. 1, Friction of the collar ; Fig. 2, The etfect of 
 
 inflammation . . . . > 
 
 VI. Protection from irritation . . 
 
 VII. Tendinous ridges .......,, 
 
 VIII. Distribution on the foot ....... 
 
 IX. Distribution on the foot ......,, 
 
 X. Distribution on the foot and on the hand . . ,, 
 
 XI. Distribution on the hand and wrist 
 
 XII. Distribution on the upper part of the body . . 20 
 XIII. Distribution on the back ....... 
 
 X I V. Distribution on the back ....... 
 
 XV. Distribution in the case of a child . . 
 
 XVI. Fig. 1, Distribution on the chest and abdomen; 
 
 Fig. 2, The popliteal space . . . ,, 
 
 XVII. Distribution on the arm ....... 
 
 XVIII. Distribution on the upper part of the body . . ,, 
 
 XIX. Distribution on the upper part of the body . . 
 
 X X. Distribution on the legs ....... 
 
 X XL Distribution on the face ......,, 
 
 XXII. Fig. 1, Distribution on the face; Fig. 2, Distri- 
 bution on the chest and abdomen . . . 
 
 XXIII. Distribution on the neck ...... 
 
 XXIV. Distribution in the case of a child 
 XXV. Distribution in the case of a woman . . . 
 
 XXVI. Distribution on the arm . ...... 
 
 XXVII. Pustular dermatitis 24
 
 xii LIST OF PLATES 
 
 PLATC FACING PAGE 
 
 XXVIII. Pustular dermatitis 24 
 
 XXIX. Chickenpox . . . . . . ., 
 
 XXX. Erytheraa multiforme .....,, 
 
 XXXI. Erythema papulatum . . . . . ,, 
 
 XXXII. Erythema rnultifortne ...... 
 
 XXXIII. Fig. 1, Erythema multiforme ; Fig. 2, Measles . 
 
 XXXIV. Acute pemphigus . . . . . ,, 
 XXXV. Fig. 1, Urticarial lesions on the hand ; Fig. 2, 
 
 Meagre variolous eruption . . . . ., 
 
 XXXVI. Chickenpox . . . . . . ,, 
 
 XXXVII. Evolution of the lesions 32 
 
 XXXVIII. Evolution of the lesions .....,, 
 
 XXXIX. (Stereoscopic.) Evolution of the lesions . . 
 
 XL. (In colour.) Early variolous vesicles . . . ., 
 
 XLL (In colour.) Advanced variolous vesicles . . ,, 
 
 XLII. (In colour.) Early variolous pustules . . ., 
 
 XLIIL (hi colour.) Advanced variolous pustules . . 
 
 XLIV. (Stereoscopic.) Variolous pustules ,, 
 
 XLV. (Stereoscopic.) Fig. 1, Variolous crusts; Fig. _'. 
 
 Spurious umbilication ...... 
 
 XLVI. Umbilication ... 
 
 XLVII. Method of outcrop 40 
 
 XLVIII. Severe confluent smallpox papular stage . . 
 
 XLIX. Severe confluent smallpox pustular stage . . ., 
 L. (Stereoscopic.) Confluent smallpox papular 
 
 stage .......... 
 
 LI. (Stereoscojnc.) Confluent smallpox vesicular 
 
 stage . 
 LII. (Stereoscopic.) Confluent smallpox pustular 
 
 stage and stage of incrustation 
 
 LIII. (Stereoscopic.) Confluent smallpox . . . ,, 
 
 LIV. (Stereoscopic.) Confluent smallpox 
 LV. (Stereoscopic.) Fig. 1, Mild confluent smallpox; 
 
 Fig. 2, Discrete smallpox . . . ,, 
 LVI. Fig. 1, Confluent papular eruption ; Fig. 2, Con- 
 fluent eruption of virulent type 
 LVII. Fig. 1, Discrete smallpox modified; Fig. 2, Con- 
 fluent smallpox modified papular sta.ge . ,, 
 LVIII. Confluent smallpox modified vesicular stage . ., 
 LIX. Confluent smallpox modified pustular stage . ,, 
 LX. (Stereoscopic.) Incompletely modified eruption .
 
 LIST OF PLATES xiii 
 
 PLATE FACIXQ PAGE 
 
 LXI. (In colour.} Modified vesicular eruption . 40 
 
 LXII. Lesions of modified smallpox . 
 
 LXIII. (Stereoscopic.} Lesions of modified smallpox . ,, 
 
 LXIV. (Stereoscopic.) Lesions of modified smallpox . ,, 
 
 LXV. Granulomata . . . . . . ,, 
 
 LXVI. A pustular syphilide ..... 56 
 
 LXVII. Variolous blebs . . . . . ., 
 
 LXVIII. Fig. 1, Lesions of inoculation ; Fig. 2, Crusts 
 
 in the soles . ...... 
 
 LXIX. (Stereoscopic.) Cicatrices on the face . . ,, 
 I . X X. Disfigurement caused by confluent modified 
 
 smallpox .......,, 
 
 LXXI. Fig. 1, Desquamation ; Fig. 2, Cicatrices and 
 
 pigmentation . . . . . ,, 
 
 LXXII. (In colour.) Obsolescent variolous eruption . ,, 
 LXXIII. Fig. 1, Pigmentation ; Fig. 2, Septic rash . 
 
 LXXIV. (Stereoscopic.) Septic rash ....,, 
 
 LXXV. Toxsemic rash, purpuric ..... 72 
 
 LXXVI. Toxa?mic rash, purpuric ...... 
 
 LXXVII. Toxaemic rose-rash, scarlatiniform ,, 
 
 LXXVIII. Toxsemic rose-rash, morbilliforni, on forearm . 
 LXXIX. (Stereoscopic.) Fig. 1, Toxaemic rash, purpuric; 
 Fig. 2, Toxaemic rose-rash, morbilliform, 
 on forearm ......,, 
 
 I.XXX. (In colour.) Toxaemic rose-rash, morbilliform, 
 
 on buttocks and thighs 
 
 LXXXI. (Stereoscopic.) Toxsemic rose-rash, morbilliform, 
 
 generalised .......,, 
 
 LXXX1I. Toxaunic rose-rash, morbilliform, generalised . 
 LXXXIII. Post-toxfemic haemorrhage .... 84 
 
 LXXXIV. Fig. 1, Post-toxaemic haemorrhage ; Fig. 2, cir- 
 cumscribed cutaneous hajmorrhagic extra- 
 vasations .......,, 
 
 LXXXV. Subvesicular and perivesicular haemorrhage . ,, 
 LX XX VI. Toxic smallpox . .... 92 
 
 LXXXYII. (Stereoscopic.) Toxic smallpox ,, 
 
 LX XX VIII. (Stereoscopic.) Toxic smallpox ,, 
 
 LXXXIX. (Stereoscopic.) Vesicular eruption of toxic 
 
 smallpox . . . . . . .100 
 
 XC. Blood-stained vesicular eruption of toxic small- 
 pox
 
 xiv LIST OF PLATES 
 
 PLATE FACIXO PAGE 
 
 XCI. (In colour.} Blood-stained papular eruption of 
 
 toxic smallpox . . . . . . 100 
 
 XCII. Measles 116 
 
 XCIII. (In colour.) Measles ......,, 
 
 XCIV. Papular variolous eruption mistaken for measles. ,, 
 
 XCY. Head and shoulders of a woman with measles . ,, 
 
 XCVL Erythema nummulare ....... 
 
 XCVII. Fig. 1, Erythema rheumaticum ; Fig. 2, Vesicu- 
 lar eruption in *a case of erythema multi- 
 forme ........,, 
 
 XCVIII. Fig. 1, Erythema multiforme ; Fig. 2, Erythema 
 
 papulatum .......,, 
 
 XCIX. (In colour.) Lesions of erythema papulatum . ,, 
 
 C. Erythema papulatum . . . . . . > 
 
 CL Fig. 1, Erythema multiforme; Fig. 2, Acute 
 
 urticaria ........, 
 
 OIL Acute urticaria . . . . . . >i 
 
 CHI. (In colour.) Lesions of acute urticaria . . ,, 
 
 CIV. Acute febrile erythema . . . . . ,, 
 
 CV. Acute febrile erythema . . . . . i 
 
 CVI. Acute febrile erythema . . . . ,, 
 
 CVII. Acute febrile erythema . . . . . ,, 
 
 CVIII. Fig. 1, Lesions of smallpox, superficial in position; 
 
 Fig. 2, Lesions of chickenpox . . . .124 
 
 CIX. Chickenpox ........,, 
 
 CX. Chickenpox ........,, 
 
 CXI. Chickenpox . . . . . . . ,, 
 
 CXII. Chickenpox ........,, 
 
 CXIII. Chickenpox of unusual distribution 
 
 CXIV. Fig. 1, Head and shoulders of a woman with 
 
 chickenpox ; Fig. 2, A papular syphilide . . 
 CXV. A papular syphilide . .... 128 
 
 CXVI. A papular syphilide ....... 
 
 CXV IT. A pustular syphilide . . . . . 
 
 CXVIIL (Stereoscopic.) Acne 140 
 
 CXIX. Fig. 1, Acne; Fig. 2, Acute eczema 
 
 CXX. Impetigo ......... 
 
 CXXI. Fig. 1, Lesions of impetigo ; Fig. 2, Pustular 
 dermatitis
 
 LIST OF CHARTS 
 
 CHART PACK 
 
 I. Confluent smallpox with severe suppurative fever . ' 4 
 
 II. Discrete smallpox with severe suppurative fever . 34 
 
 III. Confluent smallpox with moderate suppurutive fever . 35 
 
 IV. Severe discrete smallpox with moderate secoiMnry 
 
 fever ......... 37 
 
 V. Confluent smallpox modified. Severe toxjemic fever . 38 
 
 V I . Discrete smallpox with long pre-eruptive period . . 62 
 
 VII. Discrete smallpox without secondary fever ... 64 
 
 VIII. Variola sine eruptione . .... .65 
 
 I X. Toxic smallpox. Temperature low .... 88 
 
 X. Toxic smallpox. Temperature high .... 88 
 
 XI. Toxic smallpox. Low terminal temperature . . 89 
 
 XII. Ti >xic smallpox. High terminal temperature . . 89 
 
 XIII. Toxic smallpox. Toxremic pyrexia distinct from sup- 
 
 purative ........ 90 
 
 XIV. Statistical chart to show that immunity to vaccinia is 
 
 acquired coincidently with the onset of smallpox . 146
 
 THE 
 
 DIAGNOSIS OF SMALLPOX 
 
 CHAPTER I 
 
 INTRODUCTORY 
 
 THE times have changed since the days of Jenner. Besides 
 that we have less practice in the art, several circumstances 
 cause the diagnosis of smallpox to present to us more 
 difficulties than to our forefathers. To Jenner we owe the 
 chief of these difficulties. Through him, smallpox has 
 become a different disease, easier to suffer but harder to 
 distinguish ; and the simple rules which were once enough 
 are now sometimes apt to fail us. 
 
 Two- thirds of the errors in the diagnosis of smallpox 
 arise from its confusion with chickenpox. Only a little before 
 Jenner's time did chickenpox come to be distinguished clearly 
 from the graver disease. Indeed, it was not until well into 
 the nineteenth century that the identity of the two disorders 
 ceased finally to be a matter of serious, controversy. Even 
 at the latter end of the century Hebra appeared, like a 
 modern Nestor, maintaining still the ancient heresy. That 
 the two diseases are clinically distinct, that they are distinct 
 pathologically, that one protects in no degree against the 
 other, that there is no such thing as a hybrid between the 
 two, these now are fundamental axioms. When the two 
 things were accepted as the same and no necessity arose 
 for their distinction, half the difficulties of diagnosis had 
 not begun to exist.
 
 2 THE DIAGNOSIS OF SMALLPOX 
 
 The > impDrtftQ'cel of- 1 thtr 'problem, too, has immensely 
 in^reaise&V Once 1 it was^evetybbSv^s lot to get smallpox, 
 and tjherc .wa&\4ittie^)<ttepiptitG' segregate the afflicted. A 
 yrrofiv ^p\ni< ii was then of no great consequence, and an 
 extreme precision of diagnosis was hardly worth the trouble 
 of attaining. A correct opinion and an early opinion are 
 now of the first importance, however insignificant may be 
 the attack, and for such an opinion to be formed a close 
 scrutiny of the signs and symptoms is frequently essential. 
 But before proceeding to the analysis it will be desirable 
 to make a preliminary study of the ground to be surveyed. 
 
 Of rashes, toxwmic and focal. Everyone recognises 
 that there is a pathological distinction to be drawn between 
 such a rash as may be caused by eating shell-fish and 
 the skin-lesions of scabies or of lupus. The one is pro- 
 voked by the circulation in the blood of a chemical poison, 
 the others by the local action of certain parasites in the 
 skin. 
 
 A similar distinction is suggested by the infectious 
 exanthems whose eruptions fall, some into one class, some 
 into the other. The vesicles of chickenpox, perhaps also 
 the rose-spots of enteric fever, are caused by the local 
 action of certain micro-organisms. The rashes produced by 
 the injection of the antitoxin of diphtheria, the rash of 
 haemorrhagic diphtheria, and doubtless the rash of scarlet 
 fever also, are all caused by the circulation in the blood 
 of peculiar chemical products. 
 
 There are some differences in the clinical symptoms 
 which commonly accompany the two kinds of rashes. 
 What may be called the focal rashes do not necessarily 
 evoke any serious constitutional disturbance. If this 
 occurs, as it sometimes does, either it is in proportion to 
 the extent and severity of the focal rash, or else it is pro- 
 voked by another cause. On the other hand, the toxaemic 
 rashes are commonly accompanied by fever or by constitu- 
 tional disturbance which is caused by the same poison 
 whose circulation in the blood produces the rash itself. 
 The toxsemic rash is but one symptom of the intoxication.
 
 INTRODUCTORY 3 
 
 A further distinction lies in the fact that toxaemic 
 rashes are generally diffuse, while focal rashes are commonly 
 composed of circumscribed lesions; or the latter, if diffuse, 
 are unsymmetrical, as with erysipelas. But the point 
 must not be pressed, since circumscribed lesions are 
 met with in some drug-rashes, and also in those 
 toxaemic rashes which are made up of small haemorrhagic 
 extravasations. 
 
 The exanthems, then, are signalised in some instances 
 by a focal rash, in others by a toxsemic. Smallpox, 
 therefore, is exceptional ; for it is a disease which presents 
 examples of both kinds of rash and exhibits the symptoms 
 characteristic of each. 
 
 The variolous rashes and febrile states. When a person 
 falls ill with smallpox the first symptoms are those of a general 
 intoxication. There is a sudden rise of temperature and the 
 common symptoms of a febrile toxaemia. The duration of 
 the toxaemia is about a week, and during its course the 
 patient may develop a toxaeinic rash of one kind or another. 
 The toxaemia may even be fatal; in that case the patient 
 is said to die of haemorrhagic smallpox. This variolous 
 toxaemia is precisely analogous to that of scarlet fever, 
 and the rashes which are sometimes evoked by the former 
 are analogous to the rash which is characteristic of the latter 
 disease. 
 
 If this were all, smallpox would be a disease simple to 
 understand, if often difficult to distinguish. Its peculiarity 
 is that, half-way through the primary toxaemia, a focal 
 rash is developed, which may be insignificant, but is some- 
 times so severe as to be capable itself of causing serious 
 illness or even death. The focal rash, like most focal 
 rashes, consists of circumscribed lesions ; and the constitu- 
 tional effects which they produce are in direct proportion 
 to their number and severity. A boil is a focal lesion in- 
 considerable in effect ; but if the body were covered with boils 
 the illness to which they Avould give rise would be serious 
 and the fever considerable. It is so with the focal rash 
 and secondary fever of smallpox. A chart is reproduced
 
 4 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 which shows the distinction between the two fevers whose 
 combination makes the complete disease. 
 
 CHART i. CONFLUENT SMALLPOX WITH SEVERE SUPPURATIVE FEVER. 
 
 The secondary fever is a mere fever of suppuration. 
 The focal rash, which causes it, makes its appearance on 
 the third or fourth day of illness. The rash consists 
 of a number of skin-lesions scattered over the surface of 
 the body, each of which is the seat of inflammation so 
 intense as to lead in the course of four or five days to 
 the formation of a small abscess. Within a few days 
 more the contents dry up or are partly emptied by rupture. 
 A crust forms which becomes detached when the lesion 
 has healed and leaves a small scar if the injury was deep 
 enough. The number of lesions which are present may 
 not amount to a dozen ; or there may be many thousands 
 of them, and they may be set so closely as to conceal 
 almost the whole cutaneous surface. 
 
 The diagnosis of smallpox turns in most cases upon
 
 INTRODUCTORY 5 
 
 the character of the focal rash. The evidence presented 
 by the rash depends partly upon the anatomical character 
 of the individual lesions, partly upon their disposition in 
 relation to the surface of the body, that is to say, upon 
 their distribution. It has been the accepted teaching to 
 give precedence to the former body of evidence. That 
 practice, intelligible in years gone by when modified small- 
 pox was the exception, is now less easy to justify when 
 modified smallpox is the rule. The evidence from position, 
 there can be little doubt, is in most cases more intrinsically 
 valuable than the evidence from character ; it is certainly 
 the more easily observed and the more generally de- 
 pendable. In the chapters which follow, therefore, the 
 salient feature of the disease, the focal rash, will be described 
 first to the exclusion of the symptoms of the toxaemia; 
 and the distribution of the rash will be dealt Avith at 
 some length before an attempt is made to indicate the 
 peculiarities of the lesions of which the rash is composed.
 
 DISTRIBUTION 
 
 ALL rules have exceptions, although if we but knew it 
 there should be a reason for every irregularity. The rules 
 of distribution may be derived from an examination of the 
 rash in a number of cases of smallpox; but in certain 
 cases there will be observed some very remarkable deviations 
 from the common pattern. The irregularities to which 
 allusion is made present themselves as streaks or clusters 
 of closely-set pustules, for the existence of which, however, 
 there is generally a good and obvious reason. They may 
 be called irritation-patches. Many writers on the subject 
 have referred to them. But to regard them as pathological 
 curiosities, merely, would be a cardinal error, for by the 
 light of these exceptional instances all the common laws 
 of distribution may be explained. 
 
 Some striking examples in point are depicted in Plates I. 
 and ir. In one case the impression of a mustard-leaf came 
 out in relief. In another a crop of pustules matured after 
 an injury to the cheek. A not infrequent exciting cause 
 of such a cluster is a successful vaccinal inoculation done 
 during the period of incubation. (Plate I., Fig. 2.) The 
 patches are evoked by antecedent irritation, mechanical, 
 chemical, or inflammatory. They may be of any size; a 
 patch may cover a square foot of surface or an area no 
 bigger than a finger-nail, the less conspicuous instances 
 being relatively common. (Plates x., Fig. 2, xix., XL., and 
 LV., Fig. 2.) 
 
 The influence of attire. Even more interest attaches 
 to the curiosities of distribution caused by the friction or 
 intermittent pressure of articles of clothing. One such 
 instance is forcibly illustrated in Plate u. (Fig. 2), which 
 
 6
 
 DISTRIBUTION 7 
 
 exhibits the lines of friction of the tape and towel on the 
 abdomen of a woman. In another case (Plate in.) an 
 eruption of unwonted density was generated by irritation 
 from a vest. In the latter case the patient had been upon 
 tramp, and the eftect was enhanced by a sweaty skin. 
 Doubtless the influence of sweat is an added factor in 
 many of these cases, since they are observed more often in 
 summer than in winter. Other well-marked examples figure 
 in the illustrations. (Plate iv.) 
 
 Those are the grosser effects. Minor instances of the 
 influence of attire are more frequently encountered. The 
 pressure of a collar-stud, friction from a collar, the chafing 
 of the underclothing on the axillary folds, the pressure of 
 the corsets against the sternum, the pressure of a brace- 
 button, the rubbing of the stocking or garter against the 
 hamstrings, the chafing by the boot of the tendo Achillis 
 or of the tendons along the front of the ankle-joint; some 
 such incidents mark their effect in the majority of cases 
 of smallpox, and many secure a record in some of these 
 plates. (Plates v., Fig. 1, VHL, Fig. 1, ix., Fig. 2, x., Fig. 1, 
 xiv., xvi., Fig. 2, and xxv.) 
 
 Pathology. Irritation-patches are liable to occur on any 
 part of the body. They are not determined by heat or 
 cold, by drought or moisture. They are independent of 
 exposure to air and of protection by clothing. They occur 
 among the washed and among the unwashed, and on 
 clean parts of the skin as well as on dirty. How do they 
 happen ? The factor common to all cases is a disturbance 
 in the balance of the cutaneous circulation. And from the 
 fact that the blood-vessels are involved essentially, it may 
 be inferred that the infective particles are blood-borne, and 
 that the focal lesions are produced by the precipitation of the 
 particles out of the blood-stream into the skin. Smallpox, 
 that is to say, in its pre-emptive stage, is a septicaemia.* 
 
 This conclusion is hi harmony with what can be deduced 
 
 * The alternative hypothesis would be that the increased activity of the 
 cutaneous circulation manures a soil already containing the dormant seeds of 
 disease, most of which would otherwise fail to germinate and fructify. Stripped
 
 8 THE DIAGNOSIS OF SMALLPOX 
 
 as to the most favourable time for the effective applica- 
 tion of the irritant. In many instances it has operated in 
 the course of or before the period of incubation; but in such 
 cases the vascular consequences have persisted, or have been 
 such as might have persisted, until the onset of illness. 
 And in other cases the application of the irritant and the 
 onset of illness have been actually coincident ; or it may 
 be, even, that the former has not long preceded the outcrop 
 of the rash. 
 
 Less obvious is the exact mechanism by which the 
 precipitation is effected. An adequate explanation of an 
 irritation-patch may be, merely, that a greater volume of 
 blood passes through the capillaries of the area affected 
 and, therefore, that the number of infective particles cir- 
 culating in that area is proportionately increased. But 
 mere exuberance of blood-supply is probably not the only 
 determining factor, because inflammation of the skin does 
 not necessarily have this peculiar effect; moreover, the 
 relative excess of eruption is often out of all proportion to 
 the excess in blood-supply. (Plates n., Fig. 1, and in.) 
 An ancillary, if not the essential 'cause, should probably be 
 sought in some of the concomitant vascular changes ; in 
 an alteration of the calibre of the vessels, in a change in the 
 velocity of the blood-stream, or even, it may be, in a morbid 
 
 of metaphor and stated in pathological terms, this thesis sounds less attractive. 
 Moreover, it is difficult to reconcile with the facts set forth in the rest of this 
 chapter, and it does not harmonise with any tenable theory of the pathology of 
 the disease. 
 
 The apparent difficulty of reconciling the ordinary phenomena of the disease 
 with the assumption of a general infection by a single micro-organism has led to 
 the enunciation of various hypotheses. Thus Birdwood (Guy's Hospital Reports, 
 Vol. XLVIII., 1892) assumed smallpox to be purely a skin-disease, the infection 
 single and engrafted from without. Perhaps the favourite hypothesis has 
 been that which assumes a general specific infection predisposing to and allow- 
 ing of a secondary infection by ordinary pyogenic organisms', to which the 
 cutaneous lesions are due wholly or in part. Felix, however (Bulletin de la 
 Soc. Vaudoise des Sc. A'at., Vol. xxxix., 1903), suggested a double simultaneous 
 infection through the mucous membranes by a specific micro-organism and by 
 unspecific streptococci; and Washbourne (Guy's Hospital Gazette, Vol. xv., 
 1901) suggested a similar conjoint infection by two unknown confederated 
 organisms, both specific.
 
 DISTRIBUTION 9 
 
 alteration of the endothelial Avail. The mechanism of pre- 
 cipitation must be something in the nature of an embolism. 
 It is not necessary to suppose that the embolic particle 
 actually blocks the vessel; more probably, it becomes 
 attached to the wall of the capillary loop in a papilla.* And 
 what would best conduce to that event would be not so much 
 a greater flow of blood, which would merely cause a greater 
 number of infective particles to pass through the loop in a 
 given time, as an actual slowing of the current, which would 
 assist in their precipitation. 
 
 Such a slowing of the blood-current occurs during inflam- 
 mation, though not in all stages of it nor, necessarily, in all 
 parts of the inflamed surface. While an increased velocity 
 would, in itself, cause a greater difficulty in the deposition 
 of the infective particles, too great a slowing or an actual 
 stoppage of the current, by stopping the circulation of the 
 infective material, would tend, unless the particles were 
 present in inordinate numbers, to precisely the same result. 
 In fact, evidence is sometimes presented that blood-stasis 
 is unfavourable to the development of the rash. A strong 
 stimulus for example, that of a mustard-leaf may cause an 
 actual blood-stasis and determine an absence of the rash over 
 the area of application. The point receives illustration in 
 Plate v., Fig. 2. (See also Chapter X., p. 69.) 
 
 Cutaneous stimulation. In many of the instances where 
 an aggregation of pustules can be observed, the skin has been 
 irritated but not inflamed. In many cases the irritation was 
 so slight that the patient was unconscious of it, though the 
 position of the patch on some part of the surface which is 
 commonly exposed to friction demonstrates the cause of its 
 origin. To the production of a temporary or of a periodical 
 slowing of the capillary blood-current, actual inflammation, 
 indeed, is by no means necessary. Mere stimulation of the 
 skin causes first contraction, then expansion, and lastly 
 
 * It does not follow that such a particle must have an excessive minuteness. 
 By agglutination into a clump, and by an aggregation of leucocytes around 
 such a clump, a mass might be formed sufficient even for the occlusion of a 
 
 vessel.
 
 10 THE DIAGNOSIS OF SMALLPOX 
 
 re-contraction of the arterioles. And a stimulus, constantly 
 repeated, will cause the blood-vessels so to oscillate that there 
 will be an alternation of an increased and a diminished 
 velocity. Doubtless in most of these cases such a periodical 
 slowing of the current is the determining factor. 
 
 The converse holds good. During the earliest stage ot 
 the illness, if a part of the skin be artificially protected from 
 stimulation, that part will become liable to the eruption in 
 less degree than the corresponding area on the other side 
 of the body. Convincing illustrations of this fact are not of 
 frequent occurrence. They may be encountered, sometimes, 
 when the patient has fallen ill of smallpox while under 
 surgical treatment for another malady. Under such circum- 
 stances a sparse eruption is apt to be developed on the part 
 covered by the dressing ; but the dressing must not have 
 been irritative, nor must the part have been inflamed. Again, 
 when a patient comes under treatment before the outcrop is 
 complete, it is sometimes possible to produce the same effect 
 by design; but under such circumstances, as might be 
 expected, a conspicuous contrast is- not easy to obtain. 
 Plate vi. represents the issue of such an attempt. A case 
 seized at the very onset of the illness would doubtless display 
 a more striking result. 
 
 Now let the assumption be made, that to influence the 
 disposition of the eruption does not require an extra- 
 ordinary stimulus or a state of inflammation, but that the 
 trivial kinds of stimulation to which the skin is ordinarily 
 subject may upset the balance of the capillary circulation 
 sufficiently to enhance, however slightly, the susceptibility of 
 the overlying skin. Let it be assumed, further, that if the 
 skin be screened, even imperfectly, from stimulation, a 
 contrary effect will be produced. It should then follow 
 that evidence of the operation of these laws should be 
 forthcoming, not merely by a freak of fortune in the ex- 
 ceptional case, but also in the case of common sort which 
 may come under notice to-morrow. And that is just what 
 happens. Broadly speaking, the hollows and shallows of the 
 surface tend to escape the rash at the expense of the ridges
 
 DISTRIBUTION 11 
 
 and prominences. Conspicuous illustrations of the state- 
 ment are furnished in Plate vn. In those instances, the 
 prominence merely of a tendon was sufficient to attract 
 along its contour a few out of the scanty stock of pustules 
 with which the patient was endowed. The connection 
 between cause and effect is not always so clear, but a little 
 research will generally reveal it. On account of the well- 
 marked prominences and depressions which it displays, per- 
 haps the facts can most readily be demonstrated on the loot. 
 
 Distribution on the foot and hand. Relatively to the 
 rest of the body, the foot is very inconstant in its suscep- 
 tibility to the eruption. This is doubtless due in part to 
 differences in the comfort of the boot ; but a disturbing 
 factor even more cogent is the variety in the habits of the 
 patient. One who walks much will get on the foot a 
 relatively thicker rash than the patient of a sedentary life. 
 And he will come worse off than either who, unused to 
 much walking, takes to the road just before he falls ill. 
 Such factors influence not only the amount of the eruption, 
 but also its disposition. In most cases, the back of the 
 foot suffers more than the sole (Plates iv., Fig. 2, and 
 VIIL) ; but overmuch standing or walking is apt to evoke 
 an eruption of extraordinary profuseness on the soles, round 
 the margins of the soles, and over the toes. (Plate ix.) 
 
 Whatever the relative density may be on the back of 
 the foot and on the sole, very few spots are developed 
 between the toes, or in the folds beneath the toes ; for 
 these are sheltered places. Similarly, the shallow over the 
 heads of the metatarsal bones tends to escape, and the 
 hollows behind the malleoli, and the arch beneath the foot. 
 (Plate viti. and Plate iv., Fig. 2.) A dirty foot is a good 
 teacher : where the dirt sticks, from those places is the rash 
 averse ; where the dirt gets rubbed away, there the rash 
 comes thicker. The instep, especially the tendinous ridges 
 and the bony eminences, the tendo Achillis (Plate x., Fig. 1), 
 the backs of the toes, the heel, the balls of the toes, and 
 the toe-pads (Plate ix.), some or all of these the rash 
 takes for its chosen habitations.
 
 12 THE DIAGNOSIS OF SMALLPOX 
 
 Standing out as pronounced exceptions to the rule, the 
 malleoli, in many instances, enjoy a comparative immunity. 
 (Plates vin., Fig. 2, and ix., Fig. 2.) When low shoes are 
 worn, the malleoli are subject to the common law. (Plate ix., 
 Fig. 1.) The exceptional instances occur among those who 
 wear a well-fitting boot. In a foot so encased, the malleoli 
 suffer but little friction with the leather, since they are 
 situated at the fulcrum of the lever ; and since they are 
 protected by the leather from extraneous friction, they 
 are correspondingly protected from the rash. Some other 
 differences may generally be noticed, according as the 
 patient has worn boots or shoes. Round and above the 
 ankle, in the latter case, the disposition of the rash is 
 influenced by such agencies as the friction of the sock, of 
 the trouser-ends, of the skirts ; and though the incidence 
 of the rash may be less or greater, according to the 
 circumstances of the case, its disposition differs in kind 
 from that which would be produced by the boot itself. 
 
 In spite of a general similarity, hardly two feet are alike 
 in the precise manner in which the eruption is disposed. 
 Account must be taken of differences, not only in the habits 
 of the patient and in the foot-gear, but also in the conforma- 
 tion of the foot. The concavity of the sole will suffer 
 relatively less among those with high-arched feet (Plates iv., 
 Fig. 2, and ix., Fig. 1) than among the flat-footed. (Plate x., 
 Fig. 1.) The backs of the toes, as well as their extensor 
 tendons in their course over the bases of the proximal 
 phalanges, will be more subject to friction among the 
 claw-toed and will earn a thicker rash. (Plate ix., Fig. 2.) 
 The malleoli, again, and the tendinous ridges of the foot 
 vary in prominence in different persons, and produce a 
 correspondingly variable effect. In general, a plump foot 
 shows in the disposition of the eruption less conspicuous 
 contrasts than a thin one. 
 
 Because of the more even contour, the contrasts dis- 
 played by the hand and forearm are much less pronounced. 
 (Plates x., Fig. 2, and XLVI.) They may be distinct 
 enough when the hand has prominent bony and tendinous
 
 PLATE I. 
 
 Fig. 1. A mustard-leaf was applied to the chest at the onset of the illness, to- 
 relieve the epigastric pain which was one of the symptoms. 
 
 Fig. 2. The patient, whose attack was a mild one, was successfully vaccinated- 
 during the period of incubation. The four large pustules are those of 
 vaccinia ; the smaller ones clustering round them are variolous.
 
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 PLATE IV. 
 
 Fig. 1. The ring of pustules below the knee was caused by the pressure of a garter. Such 
 an effect is not very infrequent. 
 
 Fig. 2. The patient was a street urchin. The attack was not severe. The clustering of 
 pustules above the ankle was brought about by the flapping of his ragged trouser- 
 ends against the bare leg. The case furnished a good example of the method of 
 distribution on a well-shaped foot. It will be noticed that on the inner side of the 
 sole, where the arch was most pronounced, the rash was very scanty. It was 
 thickest on the balls of the toes and on the heels; but in those situations, on 
 account of the thickness of the cuticle, the eruption is not very clearly indicated.
 
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 PLATE VII. 
 
 The figures show the lesions arranged along the extensor tendons of the foot 
 
 and hand.
 
 PLATE VIII. 
 
 Fig. 1. Rash disposed characteristically on the back of the foot. The lesions 
 were strewn thickest over the tendons in front of the ankle-joint. The 
 cluster (<z) was caused by the constriction of the boot-lace. The shallow 
 groove (A) over the heads of the metatarsal bones was wholly bereft. 
 
 Fig. 2. Inner side and sole of the foot of the same patient. As happens often, 
 the sole almost wholly escaped. The rash was attracted to the back and 
 sides of the heel, but not to the groove beneath the malleolus (a). The 
 patient wore boots, and it will be noticed that no lesions appeared on 
 the point of the malleolus (b).
 
 PLATE X. 
 
 Fig. 1. The patient was flat-footed, and the eruption on the sole was there- 
 fore distributed at random. As happens frequently, the pressure ot the 
 boot caused a cluster of lesions to appear over the ten do Achillis (\ 
 
 Fig. 2. The print shows the eruption disposed chiefly on the back of the hand 
 and over the knuckles and on the backs of the fingers. Between 
 the fingers the spots are fewer. A cluster of pustules (a,) was 
 provoked by a sore on the wrist. It will be noticed that the rash was 
 deficient along the radial edge of the forearm, but a little accented 
 along the ulnar edge of the forearm and hand. This edge suffers most 
 in some cases ; in others, that ; whilst in some instances the rash is 
 equally pronounced on each. This variety has much to do with 
 differences of activity and occupation. Friction with the table, the 
 desk, or the bench would attract the rash to the ulnar edge ; freer and 
 more active movement of the arm would attract it to the radial edge, 
 which would be the more involved in friction with the sleeve (compare 
 Plates xvii., Fig. 1, and XLVI.).

 
 PLATE XI. 
 
 Fig. 1. This is from the same arm as that depicted in Plate xvn., Fig. 1, and shows a 
 characteristic disposition of the rash on the flexor surfaces of the forearm and hand. 
 The rash was more scanty on the hand than on the forearm. In the former situation 
 the spots are difficult to discern, since they were obscured by the thick cuticle of 
 the palm. On the hand they were most numerous on the thenar and hypothenar 
 eminences, and were not developed in the palmar hollow. The eruption was 
 aggravated at the flexure of the wrist () ; this point is illustrated again in the 
 next figure. 
 
 Fig. 2. Unusual arrangement of the lesions on the palm. The spots lie along the hollow of 
 the palm on either side of the line a b. It is easy to see that this arrangement 
 was brought about by holding a tool.
 
 DISTRIBUTION 13 
 
 ridges, but if it is smooth and plump the distribution 
 may be singularly even. The extensor surface sutlers 
 most, and the palm of the hand is generally compara- 
 tively immune. (Plates XL, Fig. 1, and xvn., Fig. 1.) 
 The rash tends to be most pronounced on the back of the 
 wrist and hand and over the heads of the metacarpals, 
 since those parts are the most exposed. In many cases 
 the rash is accented along the radial or ulnar edge of the 
 forearm, or along both ; and at the flexure of the wrist it 
 is sometimes exaggerated on account of the rubbing of the 
 sleeve. The incidence is distinctly less between the fingers 
 than along their backs, and in the hollow of the palm 
 than on the muscular eminences which bound it. The 
 precise disposition in a particular case depends a good deal 
 upon the patient's occupation. (Plate XL, Fig. 2.)
 
 CHAPTER III 
 
 DISTRIBUTION (continued) 
 
 Scheme of distribution. Given that the pattern of the erup- 
 tion on the foot is moulded almost wholly by circumstances, 
 is it probable that the general scheme of distribution on the 
 rest of the body is governed by an arbitrary and conventional 
 rule ? The facts are not so ; the greater includes the less, and 
 the laws which are effective for the part are valid for the 
 whole. The operative causes are manifold ; but the most 
 potent factors are exposure to air and friction with clothing, 
 and to their efficacy every case of smallpox is a testimonial. 
 
 The brunt of the attack falls upon the face and hands. 
 (Plate xii.) These are just those parts of the skin where 
 disfigurement can be worst endured, since they are kept 
 habitually uncovered. And it is because they are unclad 
 that they suffer exceptionally; for they are exposed thereby 
 to unceasing stimulation from wind and weather, from 
 changes of temperature, and from manipulation. The face 
 is exposed the more constantly, and it exceeds the hand also 
 in its blood -supply ; more infective particles pass through 
 the vessels of a given area, and they have a greater chance of 
 precipitation. For these reasons the incidence on the face is 
 greater than on any other part of the body. 
 
 On the covered parts distribution is most influenced by 
 friction with the clothing, and friction is determined by 
 movement. Of the three members the upper limb, the 
 lower limb, the trunk the first is the most mobile and the 
 most moved, and it sustains the thickest rash. (Plates XIIL, 
 Fig. 2, and xix.) In mere amplitude of movement the 
 lower limb surpasses the trunk ; but the trunk, as a rule, is 
 in more constant though in more restricted motion. Hence 
 the leg, in most cases, is less susceptible than the trunk. 
 
 11
 
 DISTRIBUTION 15 
 
 A striking characteristic of the disease is that the back 
 and front of the trunk are very differently affected. The 
 bulk of the rash is found behind. In front it is more sparse 
 than on any other large part of the surface. (Plates xvin. 
 and xix.) This peculiarity of distribution is very easy to 
 understand by considering the shape and habit of the body. 
 The flexure of the spine looks forward. Nearly every move- 
 ment, especially with the more laborious forms of toil, 
 involves the dorsal arch in friction with the underclothing. 
 The shoulders, indeed, sustain an amount of friction but 
 little less than that suffered by the arm, and it is over the 
 shoulders that the rash comes thickest. (Plates xin. and xiv.) 
 The pivot on which the trunk moves is the pelvis. In the 
 movements of the trunk, the nearer to the pivot the less is 
 the amplitude of motion. The eruption, therefore, grows 
 less from the shoulders downwards, the difference being 
 sometimes pronounced and generally distinct. The rash is 
 least across the loins, and, as might be supposed, its 
 incidence again increases over the buttocks. In front there 
 is a similar gradation, but it is more constant and con- 
 spicuous. In a case of confluent smallpox, even, the rash 
 may become excessively attenuated on the lower part of the 
 abdomen. (Plates xv., xvi., Fig. 1, and xxii., Fig. 2.) 
 
 On the limbs there is a lineal gradation of density 
 similar to that which occurs upon the trunk. The limbs 
 have most mobility at their distal ends, and the rash increases 
 in density from above downwards. (Plates XIL, xv., and 
 xxiv.) This centrifugal distribution is, in most cases, 
 particularly well displayed upon the arms. 
 
 A characteristic tendency of the rash is to shun the 
 most sheltered parts of the cutaneous surface. These are 
 the great flexures of the body. The armpit, perhaps, of all 
 parts is the most efficiently screened, and consistently enjoys 
 an immunity which is virtually complete. (Plates xvin. 
 and xxii., Fig. 2.) An immunity hardly less ample is shared 
 by the groins and the hypogastrium. (Plate xvi., Fig. 1.) 
 The flexures of the limbs are very imperfectly protected, but 
 in the bend of the elbow and in the popliteal space it is the
 
 16 THE DIAGNOSIS OF SMALLPOX 
 
 rule for the rash to be noticeably less dense than on contiguous 
 parts of the skin. (Plates xvi., Fig. 2, and XVIL, Fig. 1.) 
 
 Just as the flexures are relatively secure against the 
 rash, the counter-parts on the extensor surfaces earn a dis- 
 proportionate share. The elbow is peculiarly apt to display 
 a thick crop. (Plate xvn., Fig. 2.) Similarly the rash is 
 denser over the deltoid and on the outer surface of the arm 
 than on the inner side which comes against the chest wall 
 (Plates xviii. and xix.); it is thicker on the extensor 
 surface of the fore-arm than on the flexor ; thicker on the 
 back of the hand than on the palm. On the leg and thigh, 
 which, being less active than the arm, sustain a more scanty 
 rash, the disposition of the rash, for precisely that reason, 
 presents less conspicuous contrasts; but the contrasts exist 
 and are in the same direction. (Plate xx.) 
 
 The broad features of distribution are, therefore, that the 
 rash prefers the upper half of the body to the lower, that it is 
 a rash of the face and arms rather than of the trunk and legs, 
 that it is a rash of the distal ends of the limbs rather than 
 of the proximal, of the back of the trunk rather than of the 
 front, of extensor surfaces rather than of flexor, and that it 
 is a rash which shuns the most pronounced flexures. 
 
 The disposition in detail. In the last chapter a descrip- 
 tion was given of the detailed disposition of the rash on the 
 foot and hand. Those finer shades of contrast, though they 
 may be deemed of little moment, become of the first im- 
 portance in appropriate cases, and it is necessary to take a 
 careful account of them. But it is not on the limbs so much 
 as on other parts of the body that they assume their 
 greatest practical value. 
 
 On the face, though there is a superficial uniformity of 
 distribution, a closer examination reveals the choice of the 
 rash for the more exposed and prominent parts in contrast 
 to the more sheltered. (Plates xxi. and xxn., Fig. 1.) Its 
 aggregation about the forehead, nose, and malar prominences 
 causes it to be apportioned unequally from above down- 
 wards. A line drawn from the meatus of the ear to the ala 
 of the nose divides the face into two parts, on the lower of
 
 DISTRIBUTION 17 
 
 which the rash is noticeably less dense. The region most 
 screened from irritation is the orbit, and there the rash is 
 relatively sparse. Even the depression of the temple com- 
 monly wards off a fraction of its proper share. Under the 
 chin the rash is more scanty than above (Plate xxv.), 
 but the extent to which the submaxillary region suffers 
 depends upon the amount of fat under the chin, upon the 
 conformation of the jaw, and upon the habits of the patient. 
 Little children and people with a double chin may develop 
 an abundant eruption below the jaw. 
 
 The ear commonly displays the rash, the exposed surface 
 more than the back of the shell. The lesions are set along 
 the edge of the shell and along the convexities of its folds 
 rather than in the grooves between them. (Plate XXIL, Fig. 1.) 
 The prominence of the mastoid does not generally escape, but 
 the skin in the angle behind the ear is sheltered by the 
 ear itself, less or ixiore successfully according as the shell is 
 prominent or retracted. More conspicuous is the relative 
 immunity of the groove beneath the lobule. 
 
 The neck, lying sheltered between the protuberance of 
 the head above and of the shoulders below, is less subject 
 to the rash than either. In some cases the neck is 
 encircled by a distinct line, above and below which there 
 is a pronounced contrast in density. (Plates XLVIII. and LIV., 
 Fig. 1.) Such a line marks off the part covered by clothing 
 from that exposed to the air. In most cases this contrast is 
 wanting or inconspicuous. 
 
 The back of the neck suffers most (Plate XXIL, Fig. 1.) 
 In front, the muscular and tendinous and bony ridges at the 
 root of the neck present in appropriate cases peculiarly 
 valuable opportunities of contrast. (Plates xxm. and xxv.) 
 Even when the rash is relatively scanty, it is readily seen to 
 pick out the sterno-mastoid and its prominent tendons, and 
 the edge of the trapezius, and to avoid the suprasternal, 
 supraclavicular, and even the infraclavicular hollows. Along 
 the ridge of the clavicle, curiously, the rash is often less 
 pronounced than might be expected. 
 
 It will be noticed that the flank, lying sheltered beneath
 
 18 THE DIAGNOSIS OF SMALLPOX 
 
 the arm, suffers less from the rash than those parts of the 
 chest-wall which adjoin it in front and behind. (Plate 
 xxii., Fig. 2.) When the patient is well-built, the rash is 
 distributed differently over the prominent scapular regions 
 and in the interscapular groove (Plate XIIL), over the swell- 
 ing pectorals and in the sternal hollow. (Plate xxn., Fig. 2.) 
 Exceptionally the lines of the ribs even are mapped out. 
 (Plate xiv.) 
 
 Anomalies of distribution. If habit of life and con- 
 formation of body are the chief determining factors, why 
 is not variety in distribution commensurate with the variety 
 of form and habit among the people ? A considerable 
 divergence from the normal is seen occasionally when the 
 whole mode of life is unusual, for example in the case of 
 a bed-ridden paralytic or of a young infant. Yet the 
 difficulty is rather to explain the variations which occur 
 in common cases than to account for the prevailing 
 uniformity. For whatever the habit of the individual, the 
 relative activity of different parts of the body is much 
 the same in all. Clerk and navvy, 'alike, keep the face 
 uncovered, the arms more active than the trunk, the back 
 more exposed to friction than the chest and abdomen. It 
 must be remembered, too, that for the skin to be irritated 
 requires that it shall not have become inured to the irritant. 
 Manual labour is less hurtful to the workman's palm than to 
 the hand of the clerk. The ever- varying frictions and irrita- 
 tions falling hourly on the skin count more than the habitual 
 frictions to which it is inured. And again, when the onset 
 has been sudden and the illness severe enough to interrupt his 
 mode of life, it is of paramount importance, not so much what 
 the patient was doing when full of vigour yesterday, as what 
 he does to-day when his vessels contain the infective particles. 
 
 The trunk, of all parts, displays the most variety in its 
 liability. The relative density of the rash on the back, 
 chest, abdomen, is almost invariably maintained ; but instead 
 of coming next to the arms in its aptitude for the rash, the 
 back bears, in some cases, a crop which is relatively in- 
 conspicuous. Women and children are most apt to show
 
 DISTRIBUTION 19 
 
 this peculiarity. (Plates xm., Fig. 2, and xxiv.) The prob- 
 able cause of it is that men lead a more active life, while 
 women keep the movements of the trunk restrained and its 
 surface protected by the use of corsets. In the case of a fat, 
 sweaty woman, or with a patient whose corsets do not fit, 
 the corsets may have an opposite effect and induce the 
 development of a rash out of proportion in its density. 
 (Plate xxv.) The use of corsets, and their fit, influence 
 also the incidence of the rash on the abdomen, but in this 
 instance what counts more is the shape. Patients with thin 
 retracted abdominal walls are less likely to suffer than the 
 fat-bellied. 
 
 There is less, but still considerable, variety in the relative 
 incidence on the leg. This, again, is an effect of activity 
 and dress by which women come off the best. Children 
 are ape-like in the relative activity of the lower limbs, 
 and there is often little to choose between the density 
 on their legs and on their arms. (Plates xv. and xxiv.) 
 
 Striking variations occur in the gradations of density 
 along the length of the limbs. The rule is for the density 
 to increase from above downwards. From such differences as 
 there may be in the habits of a workman, of a woman of 
 inactive life, or of a child-in-arrns, the contrasts of the 
 normal centrifugal disposition may be either exaggerated or 
 repressed. What is more surprising is that sometimes there 
 is an actual reversal, so that the density, as with chickenpox, 
 increases from below upwards. (Plate xxvi.) Such a re- 
 versal is the more important when it is found on the arms. 
 It is most apt to occur in cases of modified jsmallpox. It 
 is not very infrequent, and usually a reference to the habits 
 of the patient does not explain it, so that it may be a real 
 disturbing factor in diagnosis. 
 
 Under such circumstances, the rash may never reach 
 the hand ; but there are other cases in which, while the 
 arm and forearm exhibit the normal gradation, the hand 
 alone enjoys a relative immunity. (Plates xvm. and xix.) 
 In rare cases there is a reversal of the order of incidence 
 on the extensor and flexor surfaces of the arm.
 
 20 THE DIAGNOSIS OF SMALLPOX 
 
 Partly that our knowledge of causes is imperfect, and 
 partly because we cannot hope to elicit all the pertinent facts 
 in every case, it is too much to expect an explanation of 
 all such vagaries. Yet the exceptional cases are fewer and 
 less misleading than they would be if we considered dis- 
 tribution to be governed by an unknown law or by an 
 empirical rule. And if a discrepancy occurs in the evidence 
 derived from a part of the eruption, it will be corrected 
 by the accumulated testimony of the whole. 
 
 The finer details of distribution exhibit similar differences, 
 and similar considerations apply. A particular prominence 
 or depression will not be similarly affected in all cases. 
 Very much will depend upon the conformation of parts in 
 each particular case. Because a few spots are seen in the 
 armpit, because the orbit is rilled, or because the rash is 
 undeveloped on a tendinous or bony ridge, that is no bar 
 to a diagnosis of smallpox. What is to the point is that, 
 taken as a whole, the protected areas are deficient in 
 eruption relatively, and the more so in proportion to the 
 degree of protection. 
 
 The scalp and air-passages. Patients differ widely in 
 the susceptibility of the scalp. In some cases it rivals 
 the face, in others it almost wholly escapes. Other causes 
 contribute to this difference, but the most telling is the 
 effectiveness of the hairy covering. Bald-headed people come 
 off the worst. 
 
 The mucous membranes of the air-passages are subject to 
 the eruption, the visible parts most liable to it being the hard 
 palate, the tip and edges of the tongue, and the pillars of the 
 fauces. Different patients show remarkable differences in the 
 susceptibility of these structures. In cases of equal severity, 
 the lesions may be few or absent, or the mouth and throat may 
 be covered by a confluent rash which may extend into the 
 larynx and trachea. Notoriously the mucous membranes of 
 different individuals exhibit great differences in the stability 
 of the vascular equilibrium. And just as they differ in their 
 susceptibility to catarrh, so do they differ in their vulnerability 
 to the rash.
 
 PLATE XII. 
 
 The rash was of characteristic distribution. There was most on the face ; after 
 the face, on the hand and upper extremity. From the hand upwards, the 
 rash diminished in density. On the front part of the trunk it was 
 deficient, especially on the abdomen.
 
 
 PLATE XIII. 
 
 Fig. 1. In this case, according to rule, the rash was thicker on the arms than on the back, 
 and thicker on the back than on the legs. On the back the rash was, relatively, 
 somewhat more profuse and was distributed more evenly than is the common lot, the 
 gradation of density from above downwards being very slight. Yet the gradation, 
 though slight, was regular, the incidence being least between the shoulder-blades and 
 across the loins, and heaviest over the shoulder-blades themselves. 
 
 Fig. 2. The back, as sometimes happens, sustained in this case a less abundant eruption 
 than the legs. On the back the rash was of characteristic distribution, diminishing 
 in density from the shoulders down to the loins. The incidence was characteristic- 
 / ally increased over the shoulder-blades.
 
 
 PLATK XIV. 
 
 The fiVnre shows a ra.-h most pronounced across the shoulders, and diminishing somewhat in 
 intensity from the spines of the scapulae downwards to the loins. At b was a cluster 
 of spots caused by the pressure of a brace-button. About the middle of the back 
 the lesions on either side of the spine showed a tendency to group themselves along 
 the lower ribs, in the directions marked by the lines a a. The fact appears more 
 distinctly when the print is inverted.
 
 r 
 
 
 PLATE XV. 
 
 The eruption in this case was obsolescent. The scabs had fallen from the upper part of the 
 body, their former position being marked out by pigment-splashes on the surface. The 
 scabs still lingered on the legs. Distribution was characteristic. The rash was most 
 dense on the face and forearms. On the upper extremities there was a distinct 
 gradation in density from the wrists upwards. On the lower extremities the gradation 
 was similar but less obvious. The rash was most scanty on the front part of the trunk, 
 but was thicker on the chest than on the abdomen.
 
 , 
 
 ' 
 
 PLATE XVI. 
 
 Fig. 1. The illustration exhibits the comparative immunity of the front part of the trunk. 
 The scanty eruption in that situation was most pronounced on the upper part of the 
 chest, and decreased in density from above downwards. The rash was especially 
 deficient in the groins ; and those parts were in great contrast with the upper parts 
 of the thighs, which sustained a crop exceptionally profuse. 
 
 Fig. 2. Back of the thigh and leg, showing the relative immunity of the popliteal space 
 (a). On one of the hamstrings a cluster of pustules had been provoked by friction 
 with a garter (ft).
 
 a S eg 
 
 P be o i- 
 
 . g o, ' 
 
 bD ft ^ ^ 
 
 'c B -9 rt 
 
 
 
 I 
 
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 ^ x fe 
 
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 - T 1
 
 PLATE XVIII. 
 
 This figure and Plate xix. are from the same case. The figure illustrates the immunity 
 the armpit, and the greater incidence of the rash on the outer side of the arm. 
 ..ompanng one limb with the other and one plate with the other, it will be seen that 
 e extensor surface of the forearm was more affected than the flexor surface, 
 ough the rash was distributed on the upper extremity much in the usual fashion 
 the case was exceptional from the relative immunity of the hand.
 
 PLATK XIX. 
 
 Comparing this plate with the last, it will be noticed that the rash had a greater 
 incidence over the deltoid and on the outer surface of the arm than on 
 the inner surface. The figure shows the rash characteristically disposed 
 upon the back ; it illustrates the gradation in density from above down- 
 wards, and the exaggeration of the eruption on the shoulder-blade. In 
 the groin a thick crop of pustules had been evoked by a boil.
 
 .2 
 
 P 9 
 
 
 - "^ r o w 
 
 S , -2 .b<3 g ~ | 
 
 
 toO-<u s 3> 
 
 J>! CS^JS^rr-^ 
 
 P ~3 ^ 'x *s ~ : '' S 
 
 "^Jjcsg^:"^ 
 
 ,,., 'Sooi^ 
 !- - i o X 
 
 i
 
 
 PLATE XXI. 
 
 The rash was most pronounced, us is customary, on the forehead and nose. A line 
 (/>) has been drawn from the ear to the nose, and above this line the spots lay 
 thicker than below. The immunity of the orbit is distinct, and, to a less degree, 
 that of the temple (a).
 
 PLATE XXII. 
 
 Fig- 1. The rash was distributed characteristically on the face and ear. It pre- 
 dominated on the forehead and nose and cheek-bone, and was sparse in the 
 orbit and on the temple (a). On the ear the lesions chose the edges and 
 convexities of the shell and the lobule, and spared the sub-lobular groove 
 (&). On the neck the rash was more pronounced behind than in front. 
 
 Fig. 2. The illustration shows the immunity of the armpit, and of the flank, 
 and of the groove over the sternum (a).
 
 5 c .2 
 
 cs 
 
 
 o 
 
 o N 
 
 c <u 
 
 c a 
 
 o es 
 
 
 o 
 
 
 C- ^ ^j 
 
 5 3 
 
 o 2= 
 
 .C.O.
 
 PLATE XXIV. 
 
 This case was oxceptional because the trunk almost entirely escaped the invasion, behind as 
 well as in front. The normal gradation in density on the limbs is well shown : but, 
 as often happens to children, the density on the legs equalled, or almost equalled, 
 th.it on the arms.
 
 PLATE XXV. 
 
 The print illustrates the deleterious effect sometimes caused by wearing corsets. The 
 rash, which should have been developed sparsely below the breasts, was unusually 
 conspicuous over the whole area which the corsets covered. On the part of this 
 area depicted the density fell but little below that on the arm. Between the breasts 
 will be observed a cluster (b) caused by the pressure of the points of the corsets. 
 Just above this cluster the rash was deficient in the intermammary groove (). 
 Near the armpit the rash w;is aggravated by the chafing of the under-clothing (c). 
 A deficiency, often to be observed, will be noticed in the eruption under the chin. 
 The case illustrates again the relative immunity of the posterior triangle of the neck.
 
 PLATE XXVI. 
 
 In this case the normal lineal gradation of density on the upper extremities 
 was reversed. This method of distribution is what occurs commonly in 
 chickenpox.
 
 ' 
 
 PLATE XXVI. 
 
 In this case the normal lineal gradation of density on the upper extremities 
 wa< reversed. This method of distribution is what occurs commonly in 
 chickenpox.
 
 CHAPTER IV 
 
 DIAGNOSIS BY DISTRIBUTION 
 
 THE eruption of smallpox is co-extensive with the cutaneous 
 circulation. Its lesions may be developed even under the 
 nails. And there is no region which is peculiar in being liable 
 to the lesions of smallpox but immune to those of other 
 diseases. The mere fact that the lesions are present or absent 
 on the soles, or on the palms, or on the mucous membrane of 
 the mouth, is irrelevant to the problem of diagnosis. 
 
 Localised or elliptic rashes. Since it is the essence of 
 this rash to be diffused over the whole cutaneous surface, a 
 pronounced limitation of the area of diffusion is generally 
 very cogent evidence that a rash is not variolous. However 
 like the lesions might be, such a limitation as that represented 
 in Plate xxvn. would put smallpox out of count. Even 
 when the rash occupies a greater space, the distinction may be 
 equally easy ; for example, if its incidence were limited to the 
 face and arms, or to the trunk of the body, or to the limbs. 
 (Plate xxvin.) In other cases the exclusion will be influ- 
 enced by the fact that the rash, though widespread, is yet 
 elliptic in incidence ; as when scabies attacks all parts except 
 the face, or chickenpox all except the arms. In these 
 examples the parts to enjoy immunity are some which it is 
 essential that a variolous rash should cover. Smallpox would 
 not be excluded necessarily if the abdomen, or even the whole 
 trunk, escaped ; yet the cases are exceptional in which those 
 parts are wholly unblemished, and their complete immunity 
 Avould tell something against that diagnosis. 
 
 Generalised rashes. When the eruption is generalised, 
 it becomes more particularly necessary to observe its order 
 of incidence. The vesicles of chickenpox are likely to be 
 strewn more thickly on the trunk of the body than on 
 
 21
 
 22 THE DIAGNOSIS OF SMALLPOX 
 
 the face and limbs, and on the proximal parts of the 
 limbs than on the distal. (Plate xxix.) An eczematous 
 rash may preponderate on the trunk rather than on the 
 face, on the front of the trunk rather than on the back, on 
 the abdomen rather than on the chest, or on the flexor 
 surfaces of the limbs rather than on the extensor. A large 
 number of cases, which might otherwise prove difficult, may be 
 distinguished by such considerations. (Plates xxx. and xxxi.) 
 
 Supposing even that there are none of these faulty 
 contrasts, the evidence would be hardly less cogent should 
 the gradation of density be inconsistent, not in kind but 
 in degree. A confluent rash ori the face would be incon- 
 sistent with a very scanty rash on the arms, a confluent 
 rash on the face and arms with a relative suppression of 
 the rash on all other parts, or a thick rash on the trunk 
 with a very scanty rash on the legs. Similarly, unless the 
 lesions were developed in insignificant number, their limita- 
 tion to one surface, even to the extensor surface, of a limb 
 would be almost as inconsistent with smallpox as their 
 limitation to one part of the body. 
 
 The gradation, again, must be orderly. With smallpox, 
 an abrupt transition of density may occur at the junction 
 of dissimilar surfaces, for instance, where the thigh meets 
 the groin. (Plates XVL, Fig. 1, and xxiv.) But as a rule, 
 and in the absence of any obvious disturbing cause, abrupt 
 transitions are unusual. Marked asymmetry, uneven grada- 
 tion over homogeneous areas, or an irrational patchiness of 
 distribution, are all against the diagnosis. (Plates xxxn. and 
 
 XXVIII.) 
 
 Lack of gradation. The fault may be, not that the 
 gradation is uneven or abrupt, but that it is absent. Cases 
 which cause sometimes a good deal of difficulty are those 
 in which a rash, generalised in distribution, shows no pro- 
 nounced preference for specific regions. In a case of measles, 
 or of generalised erythema, it may be difficult to say whether 
 the rash is thicker on the face than on the arms, on the 
 arms than on the trunk, on the trunk than on the legs; 
 because it is so equal in distribution or displays differences
 
 DIAGNOSIS BY DISTRIBUTION 23 
 
 so slight. Plate xxxiv. is from a case in which the vesicular 
 eruption resembled closely some that are seen in the severer 
 sorts of smallpox. It was strewn thickly over all parts of 
 the body, and the most obvious difference was a lack on 
 different parts of a distinct gradation of density. 
 
 A general lack of contrast rather than a faulty contrast, 
 that is a kind of negative evidence upon which it seems 
 difficult to rely. The tendency is to under-estimate its 
 value. The peculiarity of smallpox is that the differences 
 of density spring from the natural history of the disease; 
 merely the demonstration of their absence, therefore, is 
 evidence of considerable weight. In collecting such evidence 
 it is not enough to take account of the disposition of the 
 rash over large areas and to estimate its relative density 
 on different parts of the body, and on different parts of a 
 limb, and on opposite surfaces of a limb. The armpits and 
 the groins must be carefully explored ; the armpit, especially, 
 is a mine of information. (Plates xxix. and xxxi.) A want 
 of contrast or a reversed contrast in those regions is very 
 weighty evidence against smallpox. And, lastly, there are 
 the many trifling contrasts of disposition described in the 
 last chapter; these must be looked for and their absence 
 noted. 
 
 This class of evidence attains its highest value when, 
 in general outline of distribution, the variolous eruption is 
 closely simulated. With exceptional cases of chickenpox 
 the mimicry may l>e extraordinarily close; yet when the 
 details are scrutinised the similarity disappears. Some of 
 the most difficult casos which fall to be distinguished are 
 cases of measles or of generalised erythema, in which the 
 rash is so closely mimetic merely because it is immature. 
 With smallpox, the rash begins at the top and spreads 
 downwards; on the legs efflorescence is often still in- 
 complete after the lapse of forty-eight hours. (See Chap. VI., 
 p. 33, and Plate XLVII.) A similar order of development 
 occurs with measles, and may happen in a case of erythema. 
 The observer, therefore, may be required to classify a 
 papular rash occupying only the upper part of the body,
 
 24 THE DIAGNOSIS OF SMALLPOX 
 
 and for that reason presenting no distinctive features in 
 its salient lines of distribution. And what makes the task 
 harder is that a variolous rash, so immature, may itself display 
 in its order of incidence some apparent anomalies which will 
 disappear as efflorescence advances. In such cases as these, 
 when the common rules of distribution go by the board, its 
 finer details become our mainstay. If the rash comes 
 equally and indifferently in the orbits and on the forehead, 
 on the lower part of the face and on the upper, below and 
 above the chin, on both surfaces of the ear, on the lobule and 
 in the groove beneath it, if it spreads indifferently over the 
 hollows and ridges of the neck and into the armpit, then 
 with some confidence the further development of the case 
 may be awaited. (Plates xxxni. and xcv.) 
 
 Factitious exaltation of density in exotic eruptions. To 
 exclude smallpox, what is material is to establish the indiffer- 
 ence of the rash not only to exposed but also to sheltered 
 places, not only to the prominences but also to the depressions 
 of the surface. It is not pathognomonic that the rash picks 
 out a ridge, or is exaggerated on a part exposed to pressure 
 or irritation. Of such facts, a conspicuous or manifold in- 
 stance, like some of those depicted in the preceding plates, 
 may clinch the diagnosis which other evidence suggests. 
 But it is important to remember that similar phenomena may 
 be displayed by other diseases. In a case of dermatitis it 
 would not be unusual to find the pustules clustering where 
 the skin had been subject to irritation. In a case of erythema 
 the rash is sometimes accented on a prominence, or in a place 
 exposed to pressure. (Plate xxxv., Fig. 1.) A drug-rash, 
 even, such as that caused by an iodide salt, may furnish an 
 illustration of the same order of fact. And now and then a 
 case of chickenpox will display a garter-mark or the like. 
 (Plate xxxvi., Fig. 1.) Yet, in each instance, in spite of 
 the local idiosyncrasy the rash will preserve a general indiffer- 
 ence to the contours of the surface -, near the very part, even, 
 which has suffered with peculiar intensity there may be a 
 sheltered nook where the rash, instead of being deficient, is 
 just as pronounced as on most of the neighbouring skin.
 
 PLATE XXVII. 
 
 The patient hail symmetrical pustular dermatitis of the legs, the lesions of which bore a 
 close resemblance to the pustules of smallpox. The only other lesions present were a 
 few impetiginoas spots on the chin.
 
 PLATE XXVIII. 
 
 The patient had an attack of acute pustular eczema, the incidence of the rash being limited 
 to the face, neck, shoulders and arms. The gradation of density on the arms was 
 the reverse of that commonly encountered in cases of smallpox. The eruption, 
 besides, was too patchy in its incidence.
 
 
 
 I'l.ATK X\IX. 
 
 In this case of chickenpox the rash was most abundant on the trunk, and on the face it was 
 more scanty than on the chest. The lineal gradation of density on the arms was 
 what is frequent with chickenpox, unusual with smallpox. The gradation on the 
 trunk was such as is usual with smallpox, but the distribution was too random in 
 detail. It will be noticed, particularly, that the rash showed a complete indifference 
 to the armpit.
 
 
 PLATE XXX. 
 
 In this case the patient was attacked with generalised erythema, and some of the 
 lesions on the arms became vesicular. The rash was concentrated on the 
 limbs and was meagre on the face. The trunk also was attacked ; but it 
 will be observed that the incidence was on the lower part of the trunk 
 rather than on the upper part.
 
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 PLATE XXXV. 
 
 Fit;. 1. The affection in this case was acute urticaria. The rash was disposed on the hand 
 not unlike a variolous eruption. It was accented over the knuckles and over the 
 head of the radius. 
 
 Fig. 2. This figure makes a companion picture to Fig. 2 of the next plate. This was 
 smallpox, that chickenpox. In each case the rash was exceedingly meagre ; but the 
 evidence from distribution was of value. In this instance the few spots which were 
 developed came on the face and limbs, situations favoured by smallpox ; in the other, 
 with the exception of three spots which came on the face, all were on the trunk and 
 thighs.
 
 fll 
 
 o o 
 
 ) 
 
 ri "~? 
 
 ~ S S 
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 -r Cw ^ 
 
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 C -S 
 
 a ^ 
 
 S 3
 
 DIAGNOSIS BY DISTRIBUTION 25 
 
 Meagre eruptions. When the rash is scanty these in- 
 differences of distribution are more difficult to establish. The 
 hardest problems arise when the rash is both scanty and 
 widespread, for only the broader features of distribution can 
 then be taken account of, and they may happen to be uncon- 
 vincing. In such cases, to map out the spots on a chart helps 
 in deciding how lies the balance of evidence. Should the 
 lesions be very few in number, it may be that no valid 
 evidence against smallpox would lie even in a limitation of 
 their area of diffusion ; but for such evidence to be invalid 
 they must be so few that they may be counted in a figure 
 approaching a single number. And it will be still true that, 
 if they are variolous, they will be most apt to come on those 
 parts which suffer most when the rash is in plenty. They 
 should be found on the upper part of the body ; though there 
 may be no more than a dozen spots, the evidence would be 
 against smallpox if none were found upon the face. (Plates 
 xxxv., Fig. 2, and xxxvr., Fig. 2.) 
 
 The faith must never be pinned to one part of the 
 evidence only. There are exceptions to all the rules, and 
 it is not always that the disturbing cause can be detected. 
 A patient may still have smallpox though the rash come on 
 the arm more than on the forearm, or on the flexor surface 
 of a limb more than on the extensor surface, or on the 
 abdomen more than on the chest, or even though the groins 
 be filled. (See Chapter X., p. 69.) Yet all the exceptions will 
 not occur in the same case, and if there is no dearth of 
 evidence and all of it is weighed there will be little risk of a 
 faulty judgment.
 
 CHAPTER V 
 
 THE LESION 
 
 Life-history. Counting to the time of incrustration, the 
 evolution of the lesion in a case of natural smallpox occupies 
 about eight days. The exact duration of the period depends 
 upon the character of the lesion and upon the nature of the 
 case. Some of the lesions of modified smallpox hurry through 
 their life in three or four days, while in the severest cases of 
 confluent smallpox even the normal period may be prolonged. 
 In the evolution of a typical lesion the time occupied by the 
 several stages is about two days for the papule, two for the 
 vesicle, and four more until the pustule begins to incrust. 
 Relatively to the other, the duration of the papular or of the 
 vesicular stage is inconstant. A day may be taken from the 
 first and added to the second, four days still measuring their 
 combined duration. 
 
 At its birth the spot is very small, about as big as a 
 pin's head. (Plates XXXVIL, xxxvm., and xxxix.) It is just 
 a fleck in the skin, flush with the surface and imperceptible 
 to the touch. In a few hours it swells up into a raised, 
 hard, solid-feeling, pink mass, the papule. In the course of a 
 day or two the small round-topped papule begins to get 
 vacuolated at the top. This change spreads throughout the 
 lesion, which at the same time gets bigger and by the fourth 
 day of its life has become grey and translucent. The 
 smaller vesicles are generally hemispherical, the larger flat- 
 topped, and the crown of the vesicle is sometimes indented. 
 At this stage, if it is pricked or incised, the fluid contents 
 are not wholly emptied ; the cavity is loculated. The vesicle 
 remains clear for about twenty-four hours only ; its covering 
 then becomes dull and whitish, and, following this change, 
 its contents become turbid. This metamorphosis into the 
 
 li
 
 THE LESION 27 
 
 pustule is a gradual process and, if the lesion be not too 
 small, can be plainly detected to begin at the periphery and 
 to proceed towards the centre. In the intermediate state 
 between the vesicle and the pustule, a white or yellow ring 
 at the periphery of the crown encircles, iris-like, the grey 
 translucent centre, imparting to the lesion a characteristic 
 ringed appearance. (Plate XLIV.) By the sixth day the 
 lesion has turned yellow throughout and contains thin pus ; 
 the crown has become dome-shaped and the pustule has 
 arrived at maturity. 
 
 Size. From its birth to its maturity the lesion grows as 
 it ages. The largest papule is no bigger than the head of 
 a bee ; the largest vesicle may reach the size of the top of a 
 cedar pencil ; and a full-sized pustule is about three-eighths 
 of an inch across. But many of the lesions do not attain 
 these dimensions even in cases of natural smallpox. 
 
 The areola. These statements of size take no account of 
 the areola. (Plates XL., XLI., XLII., and XLIII.) This is seen 
 first during the papular stage. As the papule gains in 
 prominence it becomes encircled by a narrow erythematous 
 zone, which gets broader with the change into the vesicle. 
 The areola is biggest and brightest at the height of the 
 vesicular stage and begins .to wane with the onset of sup- 
 puration ; the pustule, when mature, has no areola. The 
 colour is light red and, under ordinary] conditions, is dis- 
 charged readily by pressure. The breadth of the zone is 
 very variable. It seems to be determined by the intensity 
 of the inflammatory reaction of the skin rather than by 
 the virulence of the destructive process. A broad areola, 
 therefore, is a good sign rather than otherwise. The biggest 
 are seen in some cases of modified smallpox, encircling 
 diminutive vesicles. In such cases the area covered may 
 be as big as a shilling, and the small vesicles so surrounded 
 look very like those met with in some cases of chickenpox. 
 
 Involnfioi). About the ninth day of efflorescence the 
 crust begins to form. In ordinary circumstances the whole 
 lesion undergoes inspissation and, in the course of a few days, 
 a solid brown disc-shaped scab is left embedded in the skin.
 
 28 THE DIAGNOSIS OF SMALLPOX 
 
 (Plate XLV., Fig. 1.) This falls off. in cases of unmodified 
 smallpox, about the fourteenth day of efflorescence. The con- 
 dition left after the fall of the scab will be referred to in 
 Chapter VIII. 
 
 Critical signs. The characteristics held traditionally to 
 be distinctive of variolous lesions are the loculation of the 
 cavity of the vesicle, its umbilication, and the solidity and 
 hardness of the papule. As reliable guides in diagnosis 
 these signs must be accepted with some qualification. It is 
 obvious that the tests with which they furnish us can be 
 applied only during a certain part of the illness. And, in 
 general, though the demonstration of the signs may be good 
 evidence in favour of smallpox, failure to demonstrate them 
 does not necessarily tell against that diagnosis. Their 
 meaning and the limits of their usefulness will be better 
 understood by reference to the histology of the lesion. 
 
 The frontispiece represents a section of a portion of a 
 variolous lesion in which vacuolation was beginning. The 
 lesion occupied the whole depth of the epidermis, had the 
 deeper layers for its floor, and was roofed by the cuticle. 
 At the centre the floor was thin, and by the further growth 
 of the lesion even the deep layer of cylindrical cells would 
 have been worn away and the corium invaded. It is owing 
 to this erosion of the regenerative cells that smallpox leaves 
 scars. Yet, though the corium suffers, it is its upper fringe 
 only, the papillary layer, which is commonly involved in the 
 area of destruction. The inflammation crowds within sharp 
 limits and does not encroach sensibly upon the true skin. 
 
 Loculation. When fluid is effused rapidly into a solid 
 tissue, the tissue splits, and splits along the line of least 
 resistance. With chickenpox the focus of activity is just 
 below the surface, and nothing confines the flow of serum 
 but the overlying sheet of horny epidermis. This the fluid 
 strips up, the natural plane of cleavage lying parallel to the 
 cutaneous surface. But with smallpox the effusion takes 
 place more deeply among the epidermal cells, where there 
 are no natural lines of parting. The columns of cells are 
 forced apart irregularly and the fissures, for the most part,
 
 THE LESION 29 
 
 are perpendicular to the surface. (See Frontispiece.) This 
 irregular splitting of the epithelial cells has the effect of 
 dividing the vesicle into many compartments. With the 
 onset of suppuration the walls which separate the compart- 
 ments break down ; the pustule is not loculated. 
 
 That the cavity is loculated, is determined by piercing 
 the vesicle and observing that all the fluid contents cannot 
 be emptied through the wound. There are many cases of 
 smallpox in which this test can be applied satisfactorily, 
 and many cases of chickenpox in which, with equal readiness, 
 the vesicles can be shown to be unilocular. Nevertheless, 
 the practical value of the test is inconsiderable ; for the 
 cases, in which the reaction is unambiguous are those which 
 can be distinguished even more readily by other means. 
 When the vesicles are small or flaccid, as may happen in 
 cases of either disease, it is so difficult to judge of the 
 completeness of the evacuation of the fluid that it is easy 
 to form an unwarranted opinion. Moreover, there are cases 
 in which the reaction to the test would really warrant a 
 wrong conclusion. Vesicles are sometimes loculated in cases 
 of chickenpox, though perhaps imperfectly loculated. On 
 the other hand, unilocular vesicles may be observed not 
 infrequently in cases of smallpox. The circumstances pro- 
 ductive of these ambiguities will be discussed presently. 
 
 The f<trftfc impression of the papule. The solidity ot 
 the papule is wholly spurious. The effect is produced by the 
 effusion of fluid under pressure. The vesicle of chickenpox is 
 caused by an inflammatory reaction equally acute ; but with 
 that disease there is ordinarily no precedent papule because 
 the pressure of the fluid effused is at once relieved by the 
 separation of the cuticle, bound down so lightly to the parts 
 below. With smallpox the focus of inflammation lies deeper ; 
 and the expansion of the fluid is restrained by the compact- 
 ness of the tissue into which it is effused. To separate the 
 cells the fluid must gain a high degree of tension ; and some 
 two days go by before it gathers force enough so to tear the 
 tissue that signs of vacuolation are perceptible to the eye. 
 Nevertheless, the vacuoles are there long before they are
 
 30 THE DIAGNOSIS OF SMALLPOX 
 
 evident and the papule derives its firmness from the tension 
 of the fluid which fills them. 
 
 When the circumstances are most favourable, the sign is 
 very characteristic. The limits of the papule are remarkably 
 distinct. It projects but little above the surface and feels like 
 a hard, round, foreign body embedded in the epidermis. 
 These qualities, being attributable to the effusion of serum 
 into a compact tissue, are best perceived on the face, where, 
 the blood-supply being most abundant, the effusion is most 
 rapid. Moreover, the frontal bone makes a convenient back- 
 ground for manipulation. The hand and forearm are also 
 situations favourable to the sign. On the soft parts, and in 
 those situations where the skin is soft and flaccid, the 
 peculiar qualities of the papule may be lost even in un- 
 exceptional cases ; and there are exceptional circumstances 
 in which they may be wholly lacking even upon the face. 
 
 Aberrant cases. There are two essential factors which 
 contribute to those distinctive characteristics of the papule 
 and the vesicle which ha^e just been described. One is 
 the acuteness of the inflammatory process, the other is the 
 position of the lesion among the deeper strata of the epithe- 
 lial cells. In cases of different kinds, one or other of these 
 factors may be wanting. From any cause which subdues the 
 intensity of the inflammation, or in any case in which the 
 lesions are abnormally superficial, the papules may be soft, 
 and the vesicles may be either imperfectly loculated or so 
 deficient in serous contents that the loculation is imperfectly 
 perceived. For the first reason these tests may fail, especially 
 if the skin is thin and flabby, when the subjects are of feeble 
 vitality and of weak circulation, as in the cases of the very 
 young or the very old. For the same reason they may fail in 
 certain of the more serious forms of smallpox in which the 
 circulation is apt to be defective, as will be related in the next 
 chapter. And for the second reason the tests may fail hi 
 cases of highly modified smallpox which are liable to be 
 signalised by particularly small and superficial lesions. It 
 must be remembered, also, that whatever the severity of the 
 attack and however resistant the papule may be destined to
 
 THE LESION 31 
 
 become in its maturity, yet at the time of its outcrop, before 
 the requisite tension has been attained in the fluid effused, it 
 may be altogether wanting in firmness. 
 
 Position. Since these signs depend upon the precise 
 depth of situation of the lesion, it is obvious that if that situa- 
 tion can be gauged its determination will furnish us with yet 
 another test. The skin of the trunk and limbs is easier to 
 manipulate than the thick skin of the face. The tissue should 
 be nipped up and rolled lightly between the finger and thumb. 
 The lesion should be well denned ; and it is generally possible 
 to estimate whether it bulks too largely in the deeper layers 
 of the skin, like an acne-spot, or is a mere excrescence on the 
 surface like a chickenpox-vesicle, or really lies embedded in 
 the epidermis. 
 
 Often the evidence appeals to the eye even better than 
 to the touch. The lesion of smallpox juts through the skin 
 and lifts the horny epidermis at an angle. (Plate XLIV.) 
 Lesions like acne-pustules or deep-seated syphilides, rooted 
 in the deeper part of the corium, have a greater thickness 
 of skin to push before them and bulge up from below with 
 a more gradual slope. (Plate cxviu.) On the other hand, 
 superficial vesicles, such as those of chickenpox, appear to lie 
 on the surface of the skin rather than within it. Though 
 the vesicle of smallpox has a steep gradient of slope, it joins 
 the flat skin-surface with a rounded angle. But the vesicles 
 of chickenpox, when the wall is thin enough, spring abruptly 
 from the surface like bubbles on soapy water. 
 
 If the lesion is found to inhabit the middle part of the 
 skin, that fact does not necessarily exclude an exotic origin. 
 A syphilitic pustule may have a situation and a character 
 indistinguishable from those of a variolous pustule. Yet, if 
 most of the pustules were found to be so situated, another 
 cause than smallpox would be improbable unless the eruption 
 were sparse. The same sort of remark is true of papular 
 lesions, not because it is uncommon for the papular lesions 
 of other diseases to be situated in the middle region, 
 but because they are seldom so well denned that their depth 
 of situation can be gauged. On the other hand, smallpox is
 
 32 THE DIAGNOSIS OF SMALLPOX 
 
 not necessarily to be excluded because the lesion is superficial 
 or because it is too soft for profitable manipulation. There 
 are exceptional cases in which the same circumstances must 
 be allowed for as were seen to operate in tempering the 
 hardness of the papule. 
 
 The two tests, that furnished by the tactile impression of 
 the papule and that afforded by estimating the position of the 
 lesion, are supplementary the one to the other and are the 
 most useful guides in determining the nature of individual 
 variolous lesions. Yet this test has the advantage over the 
 other, that it is capable of wider application. It can be 
 applied in all stages of evolution of the lesion and can be used in 
 many cases in which the papule, though of ambiguous consist- 
 ence, is still sufficiently distinct for its position to be ascertained. 
 
 Umbilication. By the term "umbilication" is understood 
 a saucer- shaped depression in a distended vesicle, or a mere 
 indentation of its surface, or even a pin-point dimpling. 
 (Plates XL vi., xxx VIIL, Fig. 2, and XL.) True umbilication is 
 peculiar to the vesicle. Pustules which have a flattened or 
 a concave surface are encountered not infrequently in cases 
 of smallpox as well as with other diseases. (Plate XLV., Fig. 
 2.) This effect is caused by the absorption of the fluid con- 
 tents of the pustule, and by the consequent sagging of its crown. 
 Vesicles, even, if they are flaccid may display a spurious 
 umbilication of precisely similar character and causation. 
 
 A spurious umbilication of the vesicles is seen, not infre- 
 quently, in cases of chickenpox. But with that disease a real 
 dimpling of the vesicle is sometimes met with. Such a 
 dimpling is caused, generally, by the crown of the vesicle 
 being tethered by the unruptured neck of a hair-follicle or a 
 sweat-gland. Seldom more than a few vesicles are so affected, 
 but in rare cases the phenomenon is more conspicuous. 
 
 Whatever the fundamental cause may be, the vesicular in- 
 dentation of smallpox, like the other signs which have been 
 discussed, depends upon the position of the lesion in the skin. 
 Inconstant always, it is absent in the majority of cases of 
 modified smallpox and invariably in the more aberrant forms 
 of it. The sign, therefore, is of little value in diagnosis.
 
 PLATE XXXVII. 
 
 In Plates xxxvu. and XXXVITI. a series of four illustrations represents the same hand 
 bearing an eruption, wholly unmodified, in different stages of evolution. In this plate 
 the rash is depicted in the papular stage. The outcrop was gradual, not half of the 
 lesions having yet appeared when the first photograph was taken. Fig. 2 was from a 
 photograph taken twenty-four hours later, and shows the papular eruption disclosed 
 almost in its full numerical severity. Many of the lesions represented in each figure 
 were in the prepapular stage, and consisted of red flecks in the skin, flush with the 
 surface. A comparison of the two figures will show the growth of the lesions in size 
 as well as in numbers, some of the older papules represented in Fig. 2 having attained 
 a considerable size.
 
 PLATE XXXVIII. 
 
 The eruption figured in Plate xxxvii. is here represented in the vesicular 
 stage. The interval which elapsed between the states represented in 
 Figs. 1 and 2 of this plate, as of the last, was twenty-four hours ; but 
 the photographic original of Fig. 1, Plate xxxvill., was taken forty- 
 eight hours later than that of Fig. 2, Plate xxxvii. The series, there- 
 fore, represents an eruption on the first, second, fourth, and fifth days of 
 efflorescence. Fig. 1 depicts the eruption at a time when the vesicular 
 change had not far advanced. Many of the lesions were still in the 
 papular stage. Comparing this print with Fig. 2, Plate xxxvii. , it will 
 be noticed that in the interval of two days the lesions had materially 
 increased in size and that a few of the vesicles had become umbilicated. 
 In the state represented in Fig. 2, Plate xxxvill., the vesicular change 
 was at its height and a few of the lesions displayed signs of impend- 
 ing suppuration. The vesicles had increased still further in size and 
 had become confluent. Many of the vesicles were umbilicated. The 
 majority, though not umbilicated, were flat-topped.
 
 PLATE XXXVIII.
 
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 CHAPTER VI 
 THE ERUPTION AND THE ERUPTIVE FEVER 
 
 ALIKE in its outcrop and in its subsequent evolution, the 
 eruption maintains a certain order of precedence. . The first 
 papule may come on the face, or on the wrist, or perhaps on 
 the trunk of the body. Yet, in broad terms, the rash begins 
 at the top and travels downwards, and invades the legs some 
 twenty-four hours after its first appearance higher up. The 
 lead so secured by the lesions on the face is maintained in 
 their further development. 
 
 In the milder sorts of cases the whole rash may be out 
 within twenty-four hours from the birth of the first papules. 
 On the other hand, in severe cases even the lapse of forty- 
 eight hours may hardly see the last arrivals. That is to say, 
 the outcrop is a gradual process not only over the whole body 
 but also on any one particular part. The papules first to 
 come on the face are not only twenty-four hours in advance 
 of those on the legs, but are also twenty-four hours in advance 
 of the laggards on the face itself. Under such circumstances, 
 the patient may exhibit on the first day of efflorescence a 
 scanty rash on the face and upper part of the body only, on 
 the second day a profuse rash on the face and a scanty rash 
 on the legs, and not until the third day a rash of normal 
 proportions in its incidence. (Plates XLVII. and xciv.) As 
 mentioned in Chapter IV., this consideration must not be 
 lost sight of in determining the distribution of a papular 
 eruption. 
 
 Confluent smallpox. During the outcrop the toxa?mic 
 fever culminates. Between that time and the time of 
 maturation there is, in a case of confluent smallpox, a striking 
 metamorphosis of the patient. (Plates XLVIII. and XLIX.) At 
 first he wears his normal aspect, altered only by the operation 
 
 D 33
 
 34 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 of the poison that is working in him. The papules of small- 
 pox seldom itch much or cause appreciable discomfort, and 
 in their size and appearance they bear no promise of the 
 events which are in train. The rash, therefore, like the 
 
 103' 
 
 DAY OF 
 DISEASE 
 DAY OF 
 
 CMUMtSCIICt 
 
 Tox/c 
 
 IIC FpVER 
 
 3 
 
 
 
 FEVER OF 
 
 7 
 
 CHART IL DISCRETE SMALLPOX WITH SEVERE SUPPUHATIVE FEVER. 
 No PRE- ERUPTIVE FEVER. 
 
 rash of measles, causes no symptoms and but little dis- 
 figurement ; as yet it is itself but a symptom. If the 
 transition were not seen, the subject of the early illness 
 would not presently be recognised. In the period of suppu- 
 ration the rash, which was once a symptom, has become the 
 disease. It clogs the features, hampers the movements, and
 
 35 
 
 enfolds the patient like a parasite. The difference in the 
 symptoms and the aspect agrees with the double sweep of 
 the temperature curve, and it is where the curve breaks that 
 the character of the symptoms changes. (See Chart I., p. 4.) 
 
 106 
 
 105' 
 
 10+ 
 
 103 
 
 102 
 
 101 
 
 100 
 
 93 
 
 98 
 
 97 
 
 TOXCEMIC FEVER 
 
 SUPIURAT'VE FIVER 
 
 CHART in. CONFLUENT SMALLI-OX ^VITH MODERATE SUPPUHATIVE FEVER. 
 
 Evolution. From the first state the patient passes by 
 easy stages in which, bit by bit, the fever loosens its hold, 
 while the rash gains more in prominence and begins to assert 
 its domination, (Plates L., LI., and LII.) TJie lesions grow
 
 36 THE DIAGNOSIS OF SMALLPOX 
 
 and about the fifth day of efflorescence, when the patient 
 feels at his best and may even have a normal temperature, 
 his face and bod}'' are covered with large flat vesicles. 
 Already the skin has begun to swell and feels stiff. The face 
 looks as if covered with a grey caul, tight-fitting, with a 
 broken surface, which partly hides but does not yet obscure 
 the shape and play of features. The patient has freed him- 
 self from the symptoms of his first illness, but has not 
 begun to taste the poison of the second, or yet to realise 
 the obsession of the rash which will engender it. 
 
 It is variable to what extent the temperature falls in the 
 stage of vesiculation, and on what day it is lowest. Most 
 often, the lowest point on the curve is reached on the fifth 
 day of efflorescence ; but, nearly as frequently, on the sixth 
 day or the fourth. (Charts i., n., and in.) Commonly, 
 even in cases of confluent smallpox, at this dip in the curve 
 the thermometer does not register more than 99. But in 
 some of the severer cases the recession is not so evident, 
 and the temperature does not fall below 101 or 102. 
 With the progress of suppuration the curve of temperature 
 again ascends and attains its acme on the ninth or tenth day 
 of efflorescence or, it may be, earlier or later according to the 
 severity of the case. 
 
 Maturation. In most cases suppuration begins on the 
 face on the fifth day of efflorescence, but is not fully developed 
 there until the sixth. And it is not until nearer the eighth 
 that the rash attains its maturity over the whole body. At 
 that time a patient with severe confluent smallpox presents a 
 very striking picture. (Plates XLIX., LII., Fig. 1, LIII., and LIV., 
 Fig. 1.) The natural features are obliterated, partly by the 
 rank growth of pustules, partly by the swelling of the skin 
 below them. The face is bigger and broader, and the patient 
 looks unnaturally aged. His orbits swell up, and the eyelids, 
 and he peers out through the slits between them. The nose 
 is thick and squat, like a bottle-nose ; the lips are like a 
 negro's, but immobile, dough-like. The cheeks are puffed out, 
 and the ears are thickened. The play of features is paralysed 
 by the mass which clogs their movements. The patient
 
 THE ERUPTION AND THE ERUPTIVE FEVER 37 
 
 mumbles when he speaks, and his voice is hoarse or whispering 
 from the swelling of his larynx. The hands are swollen, and 
 he moves his tingers like pegs. 
 
 To this loathsome, all-pervading rash the patient's fever 
 
 CHART iv. SEVERE DISCRETE SMALLPOX WITH MODERATE SECONDARY FKVBR. 
 
 and all his symptoms are due. The secondary fever is 
 purely a suppurative fever, caused by the absorption of 
 septic products from the pustules, and proportional to the 
 amount of that absorption. Partly because the rash is most 
 in plenty on the face, and partly on account of its greater 
 vascularity, it is from the face that the absorption is greatest
 
 38 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 It is an observation of Sydenham, as true as it is old, that 
 the patient's fever and his prospects of recovery are measured 
 by the amount of suppuration which the face sustains. 
 
 The sweep of the curve of temperature of the secondary 
 
 106' 
 
 105' 
 
 104' 
 
 103' 
 
 102' 
 
 101' 
 
 100' 
 
 98' 
 
 97 
 
 DAY OF 
 
 DISEASE 
 
 DAY OF 
 
 moRtsctict 
 
 TOX/EMI 
 
 A 
 
 SECONDAPJY FE fER 
 
 Y. 
 
 CHAHT v. COXFLTTEST SMALLPOX MODIFIED. SEVERE TOX;EMIC FEVEK 
 
 WITH A PUKPUHIC BASH. 
 
 fever is not so bold as of the primary. In the worst cases the 
 temperature may exceed 105. Yet in most cases of severity, 
 including many fatal cases, it does not much exceed 103 ; and 
 in the great bulk of milder cases, whether the rash is discrete 
 or confluent, it does not attain that limit. Smallpox in its sup-
 
 THE ERUPTION AND THE ERUPTIVE FEVER 39 
 
 purative stage is not, in fact, a highly febrile disorder; and the 
 skin may suffer much disturbance and cause but a trifling 
 pyrexia. With the milder sorts of discrete smallpox, febrile 
 symptoms are hardly to be looked for ; and with confluent 
 smallpox, if the suppurative process is incomplete, as it is so 
 often among vaccinated persons, the fever may be almost as 
 insignificant. (Charts iv. and v.) 
 
 Involution and termination. From about the ninth day 
 of efflorescence, in the more favourable cases, the pustules 
 dry up and scab over and, following this involution of the 
 rash, defervescence sets in quickly. (Plate LIV., Fig. 2.) In 
 the more serious cases pus, stained brown by altered blood, 
 collects below the crusts formed on the surface and may 
 exude from the broken pustules. (Plate LIL, Fig. 2.) In the 
 latter cases this period is the most critical ; for the absorption 
 of septic matter continues, the temperature remains high, 
 and there is apt to be delirium which is often violent. In 
 some of the worst cases of all, before there is time for incrus- 
 tation to occur, there is extensive shedding of the cuticle. In 
 these cases the rash is unusually profuse and the denuded 
 parts, it may be the face, or the limbs, or the back, are such as 
 are covered by a confluent eruption. Raw, weeping surfaces 
 are thereby left exposed, and the cases are nearly always 
 fatal. When death occurs during the suppurative fever the 
 fatal day is, generally, between the eleventh and fifteenth of 
 efflorescence. The fatal result is due, as a rule, either to 
 septic absorption or to broncho-pneumonia set up by the 
 affection of the air-passages. 
 
 Discrete smallpox. Cases depart from the type which 
 has been described in being either less or more serious. 
 With confluent smallpox of the milder sorts, and with 
 discrete smallpox, the domination of the rash is less pro- 
 nounced and less sustained. (Plate LV., Figs. 1 and 2.) Dis- 
 crete smallpox, unless by accident and except in infants, is 
 not a fatal disease, and in cases of no more than moderate 
 severity the secondary symptoms are insignificant. (Chart iv. 
 and Chart vn., p. 64.) This is true of the vaccinated and 
 unvaccinated alike. It must not be forgotten that even
 
 40 THE DIAGNOSIS OF SMALLPOX 
 
 among imvaccinated patients the eruption, though generally 
 unmodified, more often than not is discrete. In such cases 
 the individual lesions may be every bit as virulent as 
 in a case of unmodified confluent smallpox ; but they fail 
 in their effect from lack of numbers. The peculiarities of 
 modified smallpox are described in the next chapter. 
 
 ABERRANT ERUPTIONS OF CONFLUENT SMALLPOX 
 
 Confluent papular eruptions* Cases of unmodified dis- 
 crete smallpox, perhaps, give the least trouble of all in 
 diagnosis. On the other hand, in cases of confluent smallpox 
 the diagnosis is sometimes obscured by the very intensity of 
 the attack. In most cases the epithet " confluent " does not 
 apply until the stage of suppuration. Yet the rash is conflu- 
 ent, sometimes, even in the papular stage. The pustule may 
 be taken to be of more than twice the diameter of the largest 
 papule. The area occupied by the rash, therefore, increases 
 more than fourfold. For that reason, to be confluent in the 
 papular stage the lesions must be brought forth in great 
 multitude, and such cases are almost always fatal. (Plates 
 XLVIII. and LVL, Fig. 1.) The small red papules, each 
 surrounded by its narrow areola and projecting but slightly 
 above the surface of the skin, crowd into one another and 
 lose their identity. The face looks fiery red, and shows an 
 unbroken surface. The skin is thickened, but the par- 
 ticulate nature of the rash can hardly be perceived. The 
 surface is but roughened, and feels like russian leather. 
 This absence of discontinuity in the rash gives it a 
 superficial likeness to that of measles. And the resemblance 
 is not impaired by the fact that with smallpox the papules, 
 though confluent on the face, may be distinct on the rest 
 of the body ; for that may be the case with measles also. 
 In many cases a careful examination of the lesions on the 
 trunk and limbs will disclose their proper character. Yet 
 it often happens that the individual papules depart from 
 the type so much that their nature is liable to be mistaken. 
 The character of these aberrant lesions is very important
 
 < 2
 
 
 4 
 
 PLATE XLVMI. 
 
 A patient with severe confluent smallpox. The face was covered with a profuse 
 papular eruption. It will be noticed that in this state there was little 
 alteration of the natural features. The point is not very well shown in the 
 print, but the rash displayed an abrupt transition of density on the neck 
 at the collar-line (compare Plate LIV., Fig. 1).
 
 
 PLATE XI. IX. 
 
 In this case the attack was of a severity comparable to that of the last. The eruption 
 here depicted was pustular. The natural features were obliterated, and the patient, 
 who was a young woman, looked unnaturally old.
 
 II 
 
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 PLATE LVI. 
 
 Fig. 1. From a case of confluent smallpox of the severest kind. The rash was wholly 
 
 papular, but was already confluent on all parts of the face. 
 Fig. 2. A confluent pustular eruption, virulent in type. On the face the inflammatory 
 
 reaction was feeble, and the lesions were flat and flaccid. Compare the pustules on 
 
 the face with those on the hand.
 
 f 
 
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 5 -="8 
 
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 >.= a 

 
 PLATE LIX. 
 
 In this print tlie last of the series, the eruption, which should have been reaching its 
 maturity, is shown to have already become incrusted. Even the swelling of the 
 features depicted in the last print had subsided. In this case the lesions on the face 
 were of a kind very common with modified smallpox. They were small, but had 
 fleshy, deep-seated bases. Suppuration was confined to their crowns, or they failed 
 whollv to suppurate (compare Plates LXIII., Fig. 2, and LX1V., Fig. 1).
 
 1 
 a. 5 
 
 q 
 
 T3
 
 
 O _; 
 
 E - 
 
 X 
 
 c w 
 
 l 
 
 i
 
 PLATE LX1I. 
 
 Fig. i. Vesicles of modified smallpox. The lesions were small and had rounded summits, 
 
 but otherwise displayed the ordinary characteristics of vesicles of smallpox. 
 
 Fig. 2. In this case the lesions were minute and superficial. Many of them were no bigger 
 than the head of a pin, and became incrusted without suppurating.
 
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 4 
 
 PLATE I. XV. 
 
 The print depicts the wart-like masses of grannlation-tissue which in certain 
 cases of modified smallpox are left after the separation of the crusts. The 
 photograph was taken after convalescence was well established.
 
 THE ERUPTION AND THE ERUPTIVE FEVER 41 
 
 to recognise, and also the fact that they may be produced 
 by someAvhat different causes, and therefore may occur, not 
 only in this, but also in some other types of cases. 
 
 Aberrant eruptions causes and effects. The character 
 to be assumed by the lesions which may be developed in a 
 case of smallpox depends upon two factors, the potency of the 
 virus lodged in the skin, and the power of the tissues to resist 
 it. In most cases of natural smallpox there is an equal 
 fight. Some havoc is wrought by the poison; but there is 
 a healthy resistance of the tissues shown by the effusion of 
 serum, by cell-infiltration, and by other signs of inflamma- 
 tion. In some cases, where the immunity of the patient is 
 high, the fight goes all in favour of the tissues. Repair pre- 
 dominates over destruction, and such lesions are met with as 
 will fall to be described in the next chapter. In other cases 
 the battle goes the other way. The virus is too strong, or 
 the tissues are too weak. There is destruction of tissue and 
 but little attempt at resistance. The tissues do not show 
 fight, and the effect is seen in a soft papular rash and, later 
 on, in flat and flaccid vesicles. (Plate LVL, Fig. 2.) There is 
 little or no exudation of serum, and the vesicle is less like a 
 bag of fluid than a superficial slough of the epidermis. 
 
 Such a lack of resistance as causes these sluggish lesions is 
 met with in somewhat different groups of cases. It may be 
 due to an overwhelming severity of attack, as in those cases 
 of ultra-severe confluent smallpox described above. But it 
 mav be due, not so much to the virulence of the focal rash, as 
 to the patient's constitutional condition ; as, for instance, when 
 a patient who sustains an attack of confluent smallpox is 
 already the subject of a prostrating malady, such as tuber- 
 culosis. It is seen in those cases of ha?morrhagic smallpox in 
 which life is prolonged into the eruptive stage. (Plate LXXXIX.) 
 With hremorrhagic smallpox the papular rash is not neces- 
 sarily of the first degree of severity. Yet the character of the 
 disease so swamps the patient's vitality that his tissues have 
 no power to resist the virus which is deposited in the skin. 
 Indeed the primary toxaemia of natural smallpox, if the 
 poisoning be severe enough, will produce the same effect. It
 
 42 THE DIAGNOSIS OF SMALLPOX 
 
 will be seen later that in some cases the toxaemia is attended 
 by the severest prostration. And while that prostration lasts, 
 its effect is to occasion a similar want of reaction in the lesions. 
 In such cases it is remarkable to observe, when the fever 
 abates at the end of the vesicular stage, how the lesions swell 
 up and take on a healthy reaction. 
 
 Just as deficient vitality in the patient is capable of alter- 
 ing the character of the lesions, so it may hinder their 
 development. The change of the papule into the vesicle, 
 and of the vesicle into the pustule, is due as much to the 
 reaction of the tissues as to the action of the virus ; and a 
 feeble tissue-action may cause, not only anomaly of character, 
 but delay in transformation also. The vesicle is late to come, 
 and the vesicular stage is dragged out. In ordinary cases 
 the interval from the birth of the papule to the advent of 
 suppuration is about four days. In the cases under dis- 
 cussion the interval may be prolonged to five, six, or even 
 seven days. 
 
 Smallpox is not suggested by an eruption consisting of a 
 flush of soft papules, of a character more natural to measles, 
 which change so slowly to flat, grey, sodden plaques, having 
 little elevation, no serous contents, no umbilication, none of 
 the characters proper to variolous lesions. That such cases 
 are sometimes watched throughout their course, without 
 suspicion of the real nature of the disease, would be less 
 remarkable did not the distribution of the eruption so openly 
 betray it.
 
 CHAPTER VII 
 
 MODIFIED SMALLPOX 
 
 Immunity natural and acquired. By the use of the 
 terms " modified smallpox " and " abortive lesions," no 
 assumption is made as to the state of the patient with 
 regard to vaccination. All that is implied is that he 
 exhibits lesions which, in certain particulars, differ from 
 the type most common among unvaccinated patients. The 
 papules, instead of developing into the large vesicles and 
 pustules of natural smallpox, are transformed into lesions 
 which are generally smaller and often of a different con- 
 formation, which do not form pustules of the usual size or 
 wholly fail to suppurate, and which hasten through their 
 course of evolution more quickly than is natural. 
 
 The pathological significance of this kind of eruption has 
 already been explained. There is a high power of resistance 
 to the virus provoking the inflammation and, in consequence, 
 processes of repair predominate over those of destruction. In 
 other words, the patient is partly immune to the poison of 
 the disease.* 
 
 But immunity may be exhibited in a different fashion. A 
 patient's attack may be a mild one, not because the lesions 
 display certain favourable characteristics, but because, irre- 
 spectively of the essential character of its elements, the rash 
 itself is sparse. A patient's susceptibility is to be measured, 
 therefore, not only by the presence or absence of modification 
 of his lesions, but also by the numerical severity of his 
 attack. 
 
 These different manifestations of immunity may occur 
 conjointly, or the one independently of the other. A patient 
 
 * It is convenient to use the word " immunity " as a relative term, and not 
 as synonymous with " complete insusceptibility to the disease." 
 
 43
 
 44 THE DIAGNOSIS OF SMALLPOX 
 
 may be immune by gift of nature or of art. If by art, the 
 eruption is generally mild as well as modified; but not in- 
 frequently the rash, though modified, is yet numerically 
 severe. When immunity is inborn, the eruption is generally 
 mild but altogether unmodified. Yet it is important to bear 
 in mind that, among the unvaeeinated, there are some < 
 in which the rash is not only mild but modified as well 
 (Plate LVIL, Fig. 1), and others, more exceptionally, in which 
 it is modified though numerically severe. It will be observed 
 then, in the first place, that the term '''modified smallpox" 
 postulates nothing about numerical severity of attack, and, in 
 the second place, that to confer immunity by vaccination is 
 merely to produce, by artifice, a natural effect 
 
 Influence of vaccination. Almost x all people are born 
 susceptible to smallpox, though not equal in susceptibility. 
 Among the unvaeeinated the attack, in the bulk of cases, is 
 of mean severity : most patients experience the severer forms 
 of discrete smallpox or the milder forms of confluent Those 
 whose natural susceptibility diverges from this mean are 
 fewer and fewer according to the extent of the divergence: 
 and there are comparatively few of the unvaeeinated who are 
 liable either to the most severe or to the very mildest attacks. 
 
 Whatever his natural susceptibility may have been, when 
 a person for the first time is vaccinated the immediate effect 
 is such an augmentation of his natural immunity as to make 
 him wholly insusceptibla With the lapse of years the 
 immunity so acquired will wane, and after a sufficient interval 
 of time will wholly disappear, leaving him just that modicum 
 of natural immunity with which he started. Should he get 
 smallpox then, he would get an attack of just that severity 
 which he would have experienced had he never been vaccinated 
 at all 
 
 Now should such a person get smallpox in the int- 
 before his acquired immunity has worn away, he would be 
 open to an attack of any degree of numerical severity up 
 to the limit set by his natural immunity. He might even 
 reach that limit yet still preserve a residuum of acquired 
 immunity. A person, indeed, who has lost just so much of
 
 MODIFIED SMALLPOX 45 
 
 his acquired immunity as to render him liable to smallpox 
 of that numerical severity to which he was by nature liable, 
 has by no means lost all his protection, and if he were 
 attacked would have an eruption still considerably modified. 
 The two faculties of the vaccinal immunity wane together; 
 but the protective influence against numerical severity of 
 attack goes quicker, and the faculty to cause an eruption to 
 be modified is retained for years after the other faculty has 
 been wholly lost. The duration of each kind of acquired 
 immunity varies with different people. With some, immunity 
 of both sorts is lost in less than twenty years ; with others, 
 traces remain for a lifetime. 
 
 The fact, that with the gradual attrition of vaccinal 
 immunity the power of checking the numerical severity of 
 attack goes first and the faculty of modifying the lesions 
 lasts longer, has the notable consequence, already alluded to, 
 that vaccinated patients often get eruptions which, though 
 modified, are of considerable numerical severity. For, taking 
 the large class of those who have lost their protection against 
 numerical severity of attack but retain that against virulence 
 of lesion, the members will be arranged after just the same 
 plan as governs the severity of attack among the unvac- 
 cinated, and most of them will be liable to attacks of mean 
 numerical severity. This does not imply that smallpox 
 among the vaccinated is generally of mean numerical 
 severity ; for, in the still larger class of those who have 
 not yet lost protection against numerical severity of attack, 
 discrete smallpox predominates and swamps the severer 
 cases in the former class. Smallpox of the vaccinated, 
 therefore, differs from smallpox of the unvaccinated, not 
 only in the preponderance of mild and modified cases, but 
 also in the fact that even those who get the more severe 
 attacks will be likely to exhibit more or less modified 
 eruptions. 
 
 Confluent eruptions modified. When a patient suffers 
 an attack of smallpox with a well-modified, confluent erup- 
 tion, the course of the illness is very surprising to the 
 observer. It begins with a severe toxaemia, and the patient
 
 46 THE DIAGNOSIS OF SMALLPOX 
 
 gets a thick rash of papules which have no feature beyond 
 the ordinary. There is nothing to dispel the shadow of 
 threatened events. Not until the vesicular change is well 
 advanced, or suppuration has begun, does the benign char- 
 acter of the rash deckre itself. (Plates LVIL, Fig. 2, LVIII., 
 and LIX.) When suppuration sets in, the patient, who 
 should be ill, feverish, and prostrate, whose bloated features 
 should be covered with large, wart-like pustules, throws off 
 his symptoms and is encumbered, but not enchained, by a 
 rash which strews his face with a mere stubble of pus-capped 
 pimples. (Chart v., p. 38.) 
 
 Nevertheless, modified smallpox may be a fatal disorder. 
 For, in broad terms, the liability to death depends upon 
 the measure of the total suppurative process. Unless the 
 abortive character be very well marked, suppuration, though 
 reduced in amount, is in modified lesions by no means 
 absent. In a case of confluent smallpox, numerically severe 
 yet slightly modified, the amount of suppuration may be 
 the equivalent of that in a case of natural smallpox of a 
 numerical severity which is only moderate ; and this amount 
 of pus-formation may be sufficient to determine a fatal issue 
 in each case. The fact is, that it takes more -rash to kill 
 when the rash is modified, and that it takes more and more 
 rash to kill according to the degree of modification. 
 
 Eruptions incompletely modified. It must be under- 
 stood that the character of the lesions is not necessarily 
 uniform in a particular case. There is no distinct dividing 
 line between modified and natural smallpox. In most cases 
 of natural smallpox whether the patient has or has not 
 been vaccinated is immaterial a minority of the lesions 
 are small or abortive. (Plate XLVI.) In such cases the 
 eruption is not described as modified, because there is an 
 immense preponderance of lesions which are not atypical. 
 When atypical lesions preponderate or contribute to the rash 
 in large proportion, the eruption is said to be modified more 
 or less completely. Modification is always most in evidence 
 on the face, and it may be displayed by the bulk of the 
 lesions developed in that situation when it is lacking to
 
 MODIFIED SMALLPOX 47 
 
 those on other parts of the body. But these incompletely 
 modified eruptions often exhibit, both on the face and else- 
 where, the greatest diversity in the character of the lesions 
 which exist side by side ; some may be quite abortive, others 
 only slightly modified, and others again may be natural. 
 (Plates LX. and XL.) The kind of rash, which occurs in a 
 case in which the whole vaccinal immunity has almost dis- 
 appeared, is such a mixed rash of natural and modified 
 lesions. It is that kind of borderland case which is so apt 
 to be fatal if the rash is sufficiently abundant. 
 
 Characteristics of modified lesions. The various types 
 round which modified lesions may be grouped are to some 
 extent characteristic of different cases, but in many cases 
 lesions of diverse type are commingled. 
 
 When the eruption is in the papular stage it is seldom 
 possible to distinguish modified from natural smallpox, and it 
 is not until the lesions have become vesicular or pustular that 
 the differences become manifest. In many instances the 
 difference is almost wholly of size, and the lesions merely re- 
 produce on a reduced scale the characteristics of normal 
 lesions. (Plates LXI. and LXII., Fig. 1.) Sometimes this copy- 
 ing in miniature is carried to an extreme. The irritative 
 action of the virus is then so slight as to evoke only an insig- 
 nificant reaction of the tissues ; and, though the lesions may 
 not differ materially in shape from those of natural smallpox, 
 they are much more superficial and very rapid in evolution. 
 (Plate LXII., Fig. 2.) 
 
 Sometimes the difference is not so much in size or shape 
 as in depth of situation only, and lesions are found which, 
 while of moderate size, are obviously superficial and perhaps 
 unloculated. (Plate LXIIL, Fig. 1.) Lesions of this kind are 
 peculiarly apt to occur on the soft skin of the trunk, and on 
 those parts may sometimes be met with even in cases of 
 natural smallpox. 
 
 With lesions of another type, though there may be 
 differences from natural lesions in size and shape, the root- 
 character of the difference lies in the inflammatory process. 
 Under these circumstances the irritant which provokes the
 
 48 THE DIAGNOSIS OF SMALLPOX 
 
 lesion, though insufficient to cause so much destruction of 
 tissue as in a case of natural smallpox, is nevertheless capable 
 of evoking a very pronounced reaction which is displayed by 
 the formation of new cell-tissue in the base of the lesion. 
 These lesions lose, in part, the character of an abscess and 
 take on something of the nature of a granuloma. They con- 
 sist of fleshy elevations with shelving sides, and are deeply 
 rooted in the skin. (Plates LXIII., Fig. 2, and LXIV., Fig. 1.) At 
 the top of the mass there is a more or less imperfect vesicle 
 or pustule. Though they are of a different structure, such 
 lesions may be just as big as those of natural smallpox. They 
 are developed chiefly on the face ; and, in that situation, they 
 are apt to leave wart-like excrescences which persist long 
 after the recovery of the patient. (Plate LXV.) 
 
 Lesions of this peculiar nature are most characteristic 
 when they are large. Smaller lesions of the same kind are 
 less readily distinguished from some of the varieties already 
 described, into which, indeed, they imperceptibly merge. 
 Yet, especially on the face, even the more perfectly modified 
 and smaller lesions are apt to take on something of the same 
 character ; that is to say, to assume the form of a cone-shaped 
 fleshy base surmounted by a small vesicle or pustule. (Plates 
 LXIV., Fig. 2, and LIX.) In some instances, no sign of 
 vesiculation is ever apparent; and the lesion, though 
 persistent, may be said never to advance beyond the 
 papular stage. 
 
 Diagnosis. The large lesions of the less modified erup- 
 tions have solid bases, well defined to the touch, and embedded 
 deeply in the skin. Despite their different aspect, they are 
 as easy of recognition as are the lesions of natural smallpox. 
 Of the lesions which are, smaller and more abortive it is harder 
 to be sure. For, in proportion as they are more altered, their 
 position in the skin is more superficial and they are lacking 
 in those signs on which their recognition depends. It seems 
 to be a law that the more susceptible the patient, the more 
 deeply placed are his lesions. It is as though, with increasing 
 immunity, the virus must escape further from the blood-bear- 
 ing papillary layer and, under the least favourable conditions
 
 MODIFIED SMALLPOX 49 
 
 can maintain itself only in those bloodless fastnesses of the 
 upper epidermis near where the lesion of chickenpox inhabits. 
 
 In such cases many of the lesions have no characteristic 
 by which it is possible to distinguish them from those of 
 chickenpox. Yet, if the patient be seen before the pustules 
 die and scab over, their real nature is generally betrayed by 
 some of them. With a rash of scabs the thing is different, 
 for nice distinctions of depth cannot then be appreciated. An 
 added difficulty is that, since highly modified rashes signalise 
 a high degree of immunity, they are commonest among 
 children, because children are not too far advanced in years 
 from the date of vaccination. And in the case of a child, on 
 other grounds, chickenpox is often the most likely diagnosis. 
 Under such circumstances, even when the rash is scanty, its 
 distribution must be the cardinal factor in diagnosis. 
 
 Degradation of strain. The severity of an attack of 
 smallpox depends, really, on something more than the 
 measure of the patient's immunity. For, with all infectious 
 diseases and perhaps with smallpox more than most, the 
 strain of disease varies in virulence in different epidemics ; 
 some are attended by a low fatality, others by a high. The 
 severity of attack measures the resultant of the two opposing 
 forces, the patient's immunity, and the virulence of the 
 infective agent. The effect is that, in a mild epidemic, the 
 proportion of mild and modified cases is much greater than 
 in* an epidemic of a severer type, and that the difficulties of 
 diagnosis are proportionately increased. 
 
 From time to time we hear of epidemics in which the 
 illness is so inconsiderable, and the eruption of so anomalous 
 a character, that there is some hesitation about the name. If 
 the rash be unlike that of smallpox, it differs equally from 
 that of chickenpox, and opinion inclines sometimes one way 
 and sometimes the other. There may be a temptation even 
 to assume the existence of a third disease, and to invest it 
 with points of distinction from each. 
 
 This flux of opinion is caused by the prevalence of small- 
 pox of a very degraded strain of virulence. In every epidemic 
 cases arise at intervals in which the eruption is so highly 
 
 E
 
 50 THE DIAGNOSIS OF SMALLPOX 
 
 modified and the character of the lesions is so anomalous 
 that there is an inadequate basis for diagnosis ; and, given 
 an epidemic mild enough, such cases may form the bulk. 
 Yet it must not be forgotten that it is not possible for dis- 
 cordant distributions to run in series also. However much 
 the lesions may be altered in character, the scheme of their 
 arrangement will not be influenced either by the suscep- 
 tibility of the patient or by the strain of the disease.
 
 CHAPTER VIII 
 SECONDARY CHARACTERISTICS OF THE ERUPTION 
 
 THERE are certain features of the eruption which, though 
 generally of subordinate interest, come occasionally into 
 the first rank of importance. An example of a case in which 
 these secondary characteristics determined the diagnosis is 
 furnished by Plate LXVI. The rash was a syphilide. Though 
 most of the usual distinguishing features were lacking, three 
 facts may be deduced from the print, by which smallpox could 
 be safely excluded. In the first place, many of the lesions 
 were too large. Again, to some of these larger lesions there 
 was lacking a regular circular outline. Lastly, the elements 
 of the eruption were not homogeneous ; the rash was com- 
 posed, in part, of lesions which had become incrusted, in part, 
 of smaller pustules. 
 
 Heterogeneous eruptions. A want of uniformity of 
 character in the lesions is a conspicuous feature, especially, 
 of many cases of chickenpox. Vet, whether that disease or 
 another is the alternative to smallpox, such evidence must be 
 interpreted with discrimination. Merely that the eruption 
 is heterogeneous does not count for much, for it may be 
 heterogeneous with smallpox. The rapidity of evolution of 
 variolous lesions is determined chiefly by their size and by 
 their depth of situation. In cases of smallpox incompletely 
 modified, cases in which the lesions differ considerably in 
 point of size, they will differ equally in rapidity of evolution. 
 There are cases of modified smallpox in which, for this reason, 
 the want of uniformity among the lesions is a very conspicu- 
 ous feature. (Plate LXIIL, Fig. 1.) Papules arrested in de- 
 velopment, vesicles, pustules, crusts may all lie together on the 
 same square inch of surface. Moreover, even with natural 
 smallpox the outcrop is a gradual process, and the firstborn 
 
 51
 
 52 THE DIAGNOSIS OF SMALLPOX 
 
 lesions get ahead of their neighbours and show a correspond- 
 ing difference of character. 
 
 What is to the point is that with smallpox the diversity 
 of character is orderly. The smaller the lesion, and the 
 nearer it lies to the face, the greater should be its apparent 
 age. In cases of chickenpox or of syphilis the diversity is 
 fortuitous. The smaller vesicles or pustules may be inter- 
 mingled with larger crusts ; and the older lesions may be 
 found upon the face, or upon the trunk, or upon the leg. 
 
 Rapidity of evolution. The rapidity of evolution, the 
 inconstancy of which is a cause of the heterogeneous 
 character of certain variolous eruptions, is itself in some cases 
 pertinent to the problem of diagnosis. Ordinarily the erup- 
 tion is pustular throughout within eight or nine days of the 
 outcrop, and on the face some two days earlier. The cases of 
 smallpox in which those limits are exceeded are conspicuously 
 distinguished by the severity of the constitutional symptoms 
 and by the anomalous character of the rash. (See Chapter vi., 
 p. 42. ) Eruptions of ordinary character, consisting of vesicles 
 wholly or in part, are therefore unlikely to be variolous if their 
 age exceeds a week. Smallpox can be less safely excluded 
 on account of undue rapidity of evolution. Only when the 
 lesions approximate in size to those proper to natural smallpox 
 can the rapidity of their maturation be adduced as rebutting 
 evidence. 
 
 Shape and Size. Marginal outline furnishes, sometimes, 
 even more convincing evidence against smallpox than in the 
 case quoted at the beginning of the chapter. The usual 
 shape of the variolous vesicle or pustule is circular. A pear- 
 shaped or asymmetrical outline is produced very frequently 
 by a double or compound focus of origin ; but such compound 
 lesions are seldom difficult to distinguish. Not infrequent, 
 also, are single vesicles or pustules with an outline which is 
 slightly oval ; these are met with most often in cases of modi- 
 fied smallpox. (Plate cvin., Fig. 1.) But oval vesicles are, 
 really, far more characteristic of chickenpox, the sign being 
 secondary to the superficial situation of the lesion ; indeed, the 
 peculiarity is of some consequence in the differential diagnosis
 
 ERUPTION : SECONDARY CHARACTERISTICS 53 
 
 of the two diseases. (See p. 119.) A distinction even more 
 striking lies in the sinuous or jagged outline of many chicken- 
 pox vesicles. (Plate cvm., Fig. 2.) Even though it may 
 depart from the round, the outline of a variolous lesion is 
 seldom otherwise than firm and regular. There are other 
 diseases besides chickenpox with which an oval or irregular 
 outline of the lesions may be a useful point of distinction. 
 
 Much less frequent are cases with which the size of the 
 lesions is a material consideration. Yet there are some which, 
 though most of the lesions come within the possible limits, 
 may be excluded by the size of a few. Pustules or scabs half 
 an inch across, or vesicles of a diameter even less, almost 
 certainly would not be variolous. A downward limit of size 
 cannot be fixed. 
 
 Blebs. The dimensional rules apply only to the specific 
 lesions. In the severer cases blebs may be developed and 
 may attain a considerable size ; but they are not specific and 
 are never very numerous. (Plate LXVII.) They are caused 
 by the detachment of the cuticle owing to the irritative action 
 of the specific pustules. They are of little importance; for 
 the specific lesions which have evoked the bleb can be readily 
 discerned to lie within it, and there is, therefore, little risk of 
 misinterpretation. 
 
 Praia-papules and lesions- of inoculation. There is, 
 however, one form of variolous lesion which may be regarded 
 as an exception to the rules in the matter both of size and of 
 shape. In dealing with the outcrop and progress of the 
 eruption, the events in its evolution are dated from the day 
 when the papules invade the face in number sufficient to take 
 account of. This invasion is generally sudden and distinct 
 enough. Yet, sometimes, there are a few scouts which pre- 
 cede the vanguard of the army. A patient will point to one 
 or two of his lesions and assert their appearance a day or two 
 before the rest. These early arrivals come mostly on the face 
 or upper part of the body. They start ahead of the rest in 
 development and maintain their precedence. And, what is 
 more noticeable, they are larger than the rest, often more 
 deep-seated, and oval or a little irregular in outline.
 
 54 THE DIAGNOSIS OF SMALLPOX 
 
 From their size and shape and general appearance arises 
 the suggestion that in some cases these proto-papules are 
 lesions of inoculation. A patient who has become infected 
 through the usual channel, the respiratory tract, still remains, 
 during the period of incubation, susceptible to an inoculation 
 through the skin. It may be that the evidence of inocu- 
 lation is convincing, both from the history furnished, and 
 from the fact that the lesions are exceptionally large and 
 resemble the lesions of vaccination. (Plate LXVIII., Fig. 1.) 
 Abnormal lesions of these kinds are enabling, sometimes, of 
 an exceptionally early diagnosis. 
 
 Obsolescent lesions. One may have to judge of a case 
 of smallpox after recovery or during convalescence ; what 
 is all-important then is the impression which the rash has 
 left upon the skin. 
 
 Crusts. The crusts separate first from the face, trunk, and 
 upper parts of the limbs. They linger longest beneath the 
 thick skin of the palms and soles. On the soles, especially, 
 they may persist for many weeks unless extracted artificially. 
 These " seeds " have a very characteristic appearance. (Plate 
 LXVIII., Fig. 2.) The thick cuticle of the sole lies over them 
 and they do not interrupt its level surface. Through this 
 translucent layer the brown disc-like scabs can be clearly dis- 
 cerned embedded in the skin below. This evidence is valu- 
 able, especially, in cases of the milder sort, in which scars 
 and pigmentation-marks are absent or evanescent; for it 
 may bring about a conviction when every other sign of the 
 disease has failed. 
 
 Scars and granulomata. It must not be supposed that 
 even natural smallpox invariably scars, or that all parts of the 
 body are equally liable to the damage. Scarring is most con- 
 spicuous on the face (Plate LXIX.), and is generally confined to 
 the face or to the face and hands. In the worst cases the 
 scalp is badly scarred and suffers a patchy alopecia. The 
 parts that suffer most of all are the nose, the forehead just 
 above the root of the nose, and the cheeks. In these situa- 
 tions, the patient often sustains a disfigurement which is even 
 more trying than the broad deep scars themselves. There is
 
 ERUPTION: SECONDARY CHARACTERISTICS 55 
 
 a fine pitting of the skin, which is relieved by the projection 
 of points and strands of young scar-tissue, so that the sur- 
 face is coarse and rough like a nutmeg-grater. (Plate LXX.) 
 Such a condition is commonest among those who have had a 
 confluent but partly abortive eruption. 
 
 An effect analogous to that last described, and one apt also 
 to be evoked by a partly abortive rash, is the development of 
 wart-like granulation-tumours. These were mentioned in the 
 last chapter. (See p. 48, and Plate LXV.) They are most fre- 
 quent on the jaAvs and cheeks and nose, and are seldom 
 seen on other parts of the body than the face, except some- 
 times on the hands and forearms. These excrescences persist 
 for many weeks, but are not permanent. 
 
 Desquamation. Desquamation, in the sense in which the 
 term is used in relation to scarlet fever, is not a symptom of 
 smallpox. Yet, round the scar or mark left by the fallen scab, 
 the cuticle often becomes partly detached and ragged. This 
 effect is most in evidence where the cuticle is thick, for 
 example, upon the limbs. It is brought about directly by the 
 damage to the skin, and is confined to the immediate neigh- 
 bourhood of the injury. Only the more deeply placed lesions 
 provoke it. In severe cases, when the lesions crowd together, 
 the effect may be pronounced (Plate LXXL, Fig. 1), but it is 
 commonly absent or inconspicuous in cases of modified 
 smallpox. 
 
 Pigmentation. More characteristic are the areas of pig- 
 mentation which are left. (Plate LXXII.) When the attack has 
 been moderately severe, the impression of the whole eruption 
 is very clearly mapped out by them, and these spots of brown 
 blood-pigment are very lasting. (Plate LXXIII., Fig. 1.) Where 
 there are scars, the pigment forms a halo round each (Plate 
 i. XXL, Fig. 2); but in most places, and indeed in most cases, 
 pigmented marks upon the surface are the only relics which 
 remain. 
 
 In cases of natural smallpox, and in the severer cases of 
 all kinds, by these scars and pigmented stains the disease 
 can be told for many weeks after the patient's recovery. The 
 distribution is as obvious as when the rash was mature. In
 
 56 THE DIAGNOSIS OF SMALLPOX 
 
 mild and modified cases the trail is not so plain. Scarring is 
 absent, and even the pigment is evanescent. In such cases it 
 is important to remember that the rash and its traces go first 
 from the face, where repair is quickest. Observation must 
 then be supplemented by inquiry to learn the true distribution 
 of the vanished eruption. 
 
 SEPTIC RASHES 
 
 During the period of involution the skin is attacked, some- 
 times, by a superficial septic dermatitis. This is consequen- 
 tial to a septic infection of the pustules, and reveals itself as 
 an erythema spreading at numerous points from the infective 
 lesions as foci. 
 
 A secondary infection of the pustules by septic organisms 
 is of common occurrence in all sorts of cases, but generally no 
 harmful consequences flow from it. That in one case among 
 many the infection should extend into the superficial layers of 
 the contiguous skin is attributable to defective vitality of the 
 tissues, due either to a pre-existing debility or, more commonly, 
 to the debilitating effect of the disease. It is the same con- 
 junction of causes -as provokes such complications as boils, 
 abscesses, and affections of the eye, to which these patients are 
 very subject. All these secondary infections are most apt to 
 appear just at the close of the suppurative fever, when they 
 often give rise to a definite febrile attack which finds its record 
 on the temperature chart. (See Charts i. and u., p. 4 and 
 p. 34.) 
 
 The red patches, caused by the septic dermatitis, at first 
 surround the infecting lesions after the manner of an areola. 
 As the patches grow bigger they merge together and the skin 
 becomes mottled by them. (Plates LXXIII., Fig. 2, and LXXIV.) 
 There is no swelling of the skin, but in some cases small thin- 
 walled vesicles and pustules are thrown out on the invaded 
 surface, more especially on the flanks and abdomen. Those 
 are, indeed, the favourite seats of the rash, and to them it may 
 be confined ; but in the more severe cases the best part of 
 the body may be invaded. Sometimes especially when the
 
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 PLATE I.XVIII. 
 
 Fig. 1. The figure shows two pustules on the arm, which were caused by the 
 accidental inoculation of variolous matter during the period of incubation 
 of a generalised attack. The evolution of the generalised eruption is not 
 so far advanced. 
 
 Fig. 2. The soles of a patient convalescent from smallpox. The brown crusts 
 were still firmly embedded under the thick cuticle.
 
 PLATE LXVIII.
 
 I 
 
 ,/ 
 / 
 
 PLATE I.XX. 
 
 The face of a man after an attack of confluent modified smallpox. In contrast with those 
 - represented in tlie last figure, the injuries in this instance were in the nature of 
 addition rather than of subtraction of tissue. In many places (a) the skin had 
 become heaped up by excessive growth of young scar-tissue. Below the orbit (b b b) 
 large patch where the skin had become rough and irregularly thickened.
 
 PLATE LXXI. 
 
 Fig. 1. Extensive desquamation on the forearm after a severe attack of smallpox. 
 Fi - 2. The back of a patient convalescent after smallpox. The white scars were sur- 
 rounded each by a halo of brown pigment.
 
 
 
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 SEPTIC RASHES 57 
 
 rash is extensive, it is apt to lose much of its mottled 
 character, and large areas may be covered by a uniform or 
 stippled erythema. 
 
 The affection, as indicated above, is accompanied by some 
 fever and malaise and, it may be, by a sore throat. It is 
 never dangerous. Its chief importance resides in the fact that 
 it is liable to be mistaken for scarlet fever or measles compli- 
 cating an attack of smallpox. Confusion with measles is less 
 likely, but, if scarlet fever is a possible alternative, it may be 
 very difficult to exclude it on the merits of the case.
 
 CHAPTER IX 
 
 THE TOX^MIC FEVER 
 
 OF this dual disease, the foregoing chapters have been occupied 
 with that part, the focal rash and the secondary fever, which 
 is generally the all-in-all both to the patient and to the 
 physician. Yet, pathologically, that part is an excrescence on 
 the other, a complication or a sequela. To the specific fevers 
 themselves, the secondary fever of smallpox bears no analogy. 
 The fever proper of smallpox is that of the septicaemia, and 
 the focal rash and the secondary fever bear the same relation 
 to it as the pneumonia to measles or the adenitis to scarlet 
 fever. 
 
 The variolous septicaemia, or rather the toxaemia which it 
 induces, though often insignificant in its symptoms and 
 results, is still a serious phase of the illness. If natural 
 smallpox could be shorn wholly of the fatal fever of suppura- 
 tion, a disease would remain comparable to scarlet fever in its 
 fatality. For the variolous toxaemia can be fatal enough, 
 though it is the custom to classify the graver forms of it 
 under the title of hsemorrhagic smallpox. These graver cases 
 will be discussed in succeeding chapters, after the milder types 
 of illness have been described and the toxaernic rashes which 
 so often accompany them. 
 
 Symptoms. The toxaemia symptoms are not very charac- 
 teristic. There is every variety in their severity and duration, 
 and they furnish scanty grounds for a guess as to the nature 
 of the illness unless the patient is known to have been ex- 
 posed to variolous infection. The symptoms do not differ 
 materially from those of some other specific fevers or, indeed, 
 from the symptoms of onset of several acute diseases. The 
 toxsamic symptoms are not usually attributed to another 
 specific fever unless associated with a toxaBmic rash. They 
 
 58
 
 THE TOX.KMIC FEVER 59 
 
 are most commonly put down to influenza or to a common 
 cold, from the symptoms of which they often present no 
 distinguishing feature. Less often, and perhaps with less 
 reason, the patient is supposed to be suffering from pneumonia, 
 or acute rheumatism, or meningitis. Such misinterpretations 
 are of little moment in the earliest stage of the illness, because 
 the disease is seldom infectious before the outcrop of the focal 
 rash. But sometimes they lead to the admission of a patient, 
 suffering from smallpox, to the wards of a hospital or infirm- 
 ary for other diseases. 
 
 Such an accident is most likely to happen when the ill- 
 ness is of some severity- In such cases the symptoms 
 commonly prominent are a high temperature, severe frontal 
 headache, and lumbar pain ; and of these the last is the least 
 constant. The range of temperature is, as a rule, higher than 
 in the succeeding fever of suppuration, the ascent of the curve 
 more abrupt but its height less sustained. A temperature of 
 103 is commonly exceeded; 104" or 105 is frequently 
 reached, and not rarely 106. (See Charts L to v.) Attending 
 these degrees of fever there is often a good deal of prostration, 
 so that the patient, if not incapacitated, is unfit or disinclined for 
 exertion. Most complaint is made of the headache, but some- 
 times that is dwarfed by the lumbar pain. From a good 
 many patients the existence of pain in the back is elicited 
 only by inquiry. Others complain of pain not so much in the 
 back as in the limbs, or " all over " ; occasionally it is con- 
 centrated in the chest or epigastrium. 
 
 The onset of illness may be abrupt, but is more often 
 gradual. The symptoms are apt to come on in the night, the 
 patient after much restlessness finding himself with a head- 
 ache and, on rising, being attacked with giddiness and nausea. 
 There is likely to be shivering, but rigors are exceptional 
 
 The acme of the fever and of the symptoms is commonly 
 reached on the second or third day of illness. In cases 
 of moderate severity the duration of the toxaemia is from four 
 to six days, the fever, the pains, and the prostration abating 
 gradually during the latter part of that time. As the 
 outcrop of the papular rash occurs most commonly on the
 
 60 THE DIAGNOSIS OF SMALLPOX 
 
 third day of illness, it will be observed that the outcrop is by 
 no means coincident with the disappearance of the febrile 
 symptoms and of the fever. 
 
 Among the other symptoms of the toxaemia may be 
 mentioned vomiting; this is a common symptom, but it 
 occurs only in a minority of the cases. Excessive salivation 
 is sometimes noticed. Sore throat is generally absent. The 
 tongue is thickly furred but is uncharacteristic. It is im- 
 portant to bear in mind that the eyes are generall} 7 suffused 
 and may be faintly injected. This trait sometimes gives colour 
 to a specious mimicry of measles, as is well brought out in 
 Plate xciv. 
 
 A very common and distressing mental symptom is sleep- 
 lessness. Delirium is less frequent, and is most apt to occur 
 in the cases of children. Mental aberration is an uncommon 
 complication, but one occasionally attended by serious conse- 
 quences. It occurs independently of febrile delirium, is not 
 accompanied by conspicuous pyrexia and, in fact, most often 
 occurs in cases of little severity. The patient may be maniacal 
 or melancholic. He has delusions. These may be success- 
 fully concealed, and the first warning of his condition, or even 
 of his illness, may be an attempt at suicide.* These mental 
 symptoms are generally of brief duration. 
 
 In some cases the illness is of still greater severity, the 
 prostration alarming and the other symptoms proportioned to 
 suit. The type of illness then approximates to that more 
 commonly met with in cases of haBmorrhagic smallpox, and 
 will be dealt with in a later chapter. On the other hand, in 
 the milder sorts of cases the symptoms grade downwards, lose 
 what little individuality they might possess, and become in- 
 distinguishable from those of many trifling disorders. In 
 some cases of smallpox inquiry fails to elicit the history of 
 toxaemic symptoms of any description. In others the duration 
 is shortened ; so that, sometimes, when the focal rash is 
 observed, and it is likely to be insignificant and abortive, the 
 
 * A patient came under the writer's observation, whose illness was unsus- 
 pected until he was under arrest for attempting suicide by leaping into the 
 Thames from the Tower Bridge.
 
 THE TOX.KMIC FEVER 61 
 
 precedent malaise has been forgotten, and the patient or the 
 doctor fails to perceive the relation between the two events 
 and misses the significance of each. 
 
 Incubation. The incubation-period of smallpox is gener- 
 ally about twelve days counting to the onset of illness, or 
 fourteen days counting to the outcrop of the rash. The 
 length of this period varies within somewhat narrow limits, 
 ranging from eleven to seventeen days reckoned to the 
 date, not of onset, but of outcrop. Periods outside those 
 limits are exceptional and should be looked upon with some 
 suspicion. 
 
 Though it is illogical to do so, it is found convenient in 
 practice to date the reckoning of the incubation-period to the 
 outcrop rather than to the onset. This is so, partly because 
 with the milder cases the symptoms of onset are apt to be 
 va^ue and their commencement hard to define, and partly 
 because, when the outcrop is taken as the determining point, 
 the incubation-period is found to be more constant in 
 duration. 
 
 Duration of the pre-eruptive period. The interval 
 between the onset and the outcrop is most frequently two 
 days ; that is to say, the outcrop occurs generally on the third 
 day of illness. But the duration of this interval is very 
 variable. The outcrop may occur on the day following the 
 onset, or may be coincident with it. On the other hand, 
 the interval may be protracted. It is very common for the 
 outcrop to occur on the fourth day of illness. Sometimes it 
 occurs on the fifth day, occasionally on the sixth, now and 
 ,r_r.iin ovt-ii as late as the seventh. (Chart VL, see also Charts 
 i. to v., and vn.) 
 
 When the interval is much prolonged, the onset is apt 
 to be more gradual than usual, the first symptoms being 
 very mild and vague. The fact, that the duration of the incu- 
 bation is more inconstant when the period is determined by 
 the onset than when it is determined by the outcrop, suggests 
 that when the pre eruptive period is protracted the interval 
 In 'tween onset and outcrop may have been prolonged at the 
 expense of the interval between exposure and onset. A case
 
 62 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 may, indeed, present evidence of the force of this explanation ; 
 as, for instance, when a patient falling ill on the tenth day 
 after exposure nevertheless develops his rash, according to 
 custom, on the fifteenth. 
 
 106' 
 
 105' 
 
 10*' 
 
 103' 
 
 IOZ' 
 
 101' 
 
 10,0 
 
 99 
 
 98' 
 
 97' 
 
 a 
 
 CHAKT vi. DISCKETE SMALLPOX WITH LONG PRE-ERUFTIVE PERIOD. 
 
 In some of the worst cases, especially in some cases of 
 hsemorrhagic smallpox, though the foregoing explanation may 
 sometimes hold good, a protracted interval between the onset 
 and the outcrop is due rather to the postponement of the date
 
 THE To X. KM 1C FEVER 63 
 
 of the latter event. In Chapter VI. it was pointed out that a 
 toxaemia of exceptional severity has sometimes the effect of 
 hindering the evolution of the lesions. And the same cause 
 may conduce not only to a protracted efflorescence of the 
 papules, but also to delay in their first outcrop. 
 
 Inter-relation of the toxsemic and suppurative fevers. 
 There is imperfect concordance between the severity of 
 the toxiL'inic symptoms and the character and consequences 
 of the focal rash. More often than not, a scanty focal erup- 
 tion is preceded by mild toxrcmic symptoms, and a plentiful 
 eruption by a severe or at least a well-marked toxaemia. But 
 exceptions are numerous in both directions. It is especially 
 noticeable that a severe toxaemia is not infrequently followed 
 by a rash which, if not insignificant hi amount, at any rate 
 induces an insignificant suppurative fever. (Chart vu., 
 see also Charts iv. and v., p. 37 and p. 38.) 
 
 Such a fortunate concurrence of events is generally due 
 to the partial disappearance of a vaccinal immunity. This 
 artificial immunity not only has the effect of modifying the 
 numerical severity of the focal rash and the suppuration of its 
 lesions but, in addition, mitigates or abolishes the toxemia. 
 As, with the lapse of years, the two first faculties become 
 gradually attenuated, so also does the last. But the pro- 
 cess of attrition is not relatively uniform. The faculty 
 retained longest, it has been pointed out, is that of preventing 
 or modifying the suppuration of the lesions. That which is 
 lost first is immunity to the toxaemia. It follows that vaccin- 
 ated persons may have lost their artificial faculty of resisting 
 the action of the toxins of the septicaemia, and may suffer a 
 toxaemic fever mild or severe as determined by nature alone, 
 and yet may exhibit a focal rash which, if not insignificant 
 numerically, is insignificant in its effects. 
 
 Variola sine eruptione. On this account it arises that, 
 among the vaccinated, cases are to be encountered in which 
 the focal rash is so disproportionate to the severity of the 
 toxaemia that the nature of the disease is mistaken, because 
 the observer, occupied by the toxaemic symptoms, disregards 
 the rash which they obscure. Indeed, it is plain that a
 
 64 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 106' 
 
 105' 
 
 104-' 
 
 103' 
 
 102' 
 
 101' 
 
 100' 
 
 99 
 
 98' 
 
 97 
 
 DAY OF 
 
 DISEASE 
 
 DAY OF 
 
 EFFLOHESCEHCE 
 
 CHART vn. DISCRETE SMALLPOX -WITHOUT SECONDARY FEVEB. 
 
 patient might develop a variolous toxsemia which would never 
 be followed by efflorescence. (See Chart vm.) Unquestion- 
 ably such cases sometimes occur, but it is generally safe to 
 neglect them since it seldom happens that the toxaemia is 
 infectious.
 
 THE TOX.EMIC FEVER 
 
 65 
 
 106' 
 
 105' 
 
 10+' 
 
 103' 
 
 102' 
 
 101' 
 
 100' 
 
 99' 
 
 98' 
 
 97 
 
 DAY OF 
 
 DISEASE 
 
 CHART vin. VARIOLA SINE Eiti I-TIOXE AFTER SUCCESSFUL VACCINATIOX 
 ox THE EIGHTH DAY AFTER EXPOSURE.
 
 CHAPTER X 
 TOX^MIC RASHES 
 
 THSE rashes, coming with the symptoms of a specific fever, 
 tempt one to suspect or proclaim the presence of a commoner 
 exanthem. The most to be expected from a knowledge of 
 them is sometimes a happy suspension of judgment. 
 
 The rashes of the variolous toxaemia, or, at any rate, one 
 kind of them, are the analogues of the erythemata of scarlet 
 fever and measles, but, unlike those eruptions, they are seen 
 only in a minority of the cases. The frequency of occurrence 
 of toxsemic rashes varies with the epidemic, but, generally, a 
 rash is not developed in more than one case out of ten. The 
 rash may appear at any time during the early and middle 
 parts of the toxaemic fever, and often does not come until 
 after the outcrop of the focal rash. The commonest time is 
 on the second or third day of illness. 
 
 There are two varieties of toxeemic rashes, the petechial 
 or purpuric, and the erythematous. This distinction is well- 
 marked clinically and expresses more than a superficial differ- 
 ence. The two varieties are characteristic of different types 
 of disease. The purpuric rash is an indication of a severe 
 toxaemia; not necessarily of a serious attack of smallpox, 
 because a severe toxaemia may or may not be followed by a 
 severe focal rash and suppurative fever. (See Chart v., p. 38.) 
 Though a severe, or even a fatal, toxaemia by no means neces- 
 sarily induces such a rash, it follows that it is relatively more 
 frequent in cases of haemorrhagic smallpox. Yet it is fre- 
 quently met with, also, in the less serious forms of the disease 
 which do not themselves endanger life but cause, at the least, 
 a noticeable illness. 
 
 The rose rashes, on the other hand, have no constant 
 relation to the character of the toxaemia. For though the 
 
 66
 
 TOX.EMIC RASHES 67 
 
 toxsemic fever is generally inild among those who exhibit 
 such rashes, it may yet be moderately severe. They are df good 
 omen, because it happens nearly always that the subjects of 
 them have either a discrete or a modified focal eruption. They 
 are, therefore, seen mostly among the vaccinated. What they 
 indicate is that the patient possesses or retains a considerable 
 amount of natural or acquired immunity. The rose rashes, 
 indeed, may be thought of as antitoxic rashes. Nevertheless, 
 it will be seen in another chapter that a very similar rash 
 to some of these occurs in certain cases of htemorrhagic small- 
 pox, but heralds death instead of recovery. (Chapter XIII., 
 p. 98.) 
 
 Purpuric or petechial rash. The development of a few 
 petechire is a common symptom of the toxsemic fever. In 
 cases of hasmorrhagic smallpox, indeed, this symptom is some- 
 times conspicuous. Yet such an exhibition of petechise, for- 
 tuitousty arranged, does not constitute the purpuric rash. It 
 is in the aggregation of petechiaB that this rash is peculiar, 
 and especially in their method of arrangement. 
 
 The essence of the rash is that it affects the great flexures 
 of the trunk, parts which seem ever to show a special tendency 
 to blood-stasis in the capillaries of the skin and to capillary 
 haemorrhage. Probably in all cases the rash in its earliest stage 
 is a simple erythema. When it is extensive in distribution 
 and developed conspicuously, it consists of a dusky rederythe- 
 matous background which is stippled with innumerable small 
 haemorrhagic extravasations resembling flea-bites. The vivid- 
 ness and depth of tint of the erythema varies from case to case 
 and with the age of the rash. The petechise, being more persist- 
 ent, may be seen for several days after the erythema has 
 faded. The erythema, indeed, in many cases is very fugitive, 
 and no more is to be noticed than a mere grouping of petechise 
 on the areas affected. 
 
 The regions most favoured are the parts near the groins, 
 and to that neighbourhood the rash often is limited. Its 
 lower boundaries in many cases are curiously distinct, 
 running slantwise towards each other across the thighs an 
 inch or two below and parallel to Poupart's ligaments.
 
 68 THE DIAGNOSIS OF SMALLPOX 
 
 (Plate LXXV.) The rash seldom extends below the upper 
 third of the thigh, even when developed most extensively 
 and profusely. The upper limits are never so distinct. 
 When the rash is pronounced it reaches upwards over the 
 flanks and the abdomen to the armpits and the chest, being 
 more vivid and closer set with petechise on the sides of the 
 body than in front. When the rash comes into the armpit, 
 it is apt also to stretch a little way down the inner side of 
 the arm ; it may even encircle the arm below the point of the 
 shoulder, the arm passing through the cincture as through 
 the sleeve of a bodice. Looked at from the front, the rash 
 seems to clothe the patient like a-vest and bathing-drawers. 
 On the back the rash generally is undeveloped. In some 
 cases, however, a band, sometimes narrow, sometimes broad, 
 stretches like an apron-string across the loins (the flexure of 
 the back) and connects the major part of the rash from flank 
 to flank. 
 
 A rash so widespread is most pronounced in the recesses 
 of the flexures, the groins, the hypogastrium, and the arm- 
 pits (Plates LXXVI. and LXXIX., Fig. 1) ; and is developed most 
 scantily on the chest and epigastrium. Yet it must not be 
 supposed that the cases are numerous in which an area so 
 extensive is covered. When the confines are narrowed, the 
 rash comes only in the most favoured parts. In most cases 
 it comes in the groins alone, or in the groins and hypogas- 
 trium, or in the groins and armpits. Less frequently it comes 
 in the armpits alone. As a rule the rash is bilaterally sym- 
 metrical, but sometimes it is more pronounced on one side of 
 the body than on the other. Occasionally it is unilateral, but 
 in such cases it is never very abundantly developed. 
 
 The limits of distribution which have been denned apply 
 more particularly to the purpuric elements of the rash. 
 When an erythematous groundwork is present, the same 
 limits apply, in general, to that also. Nevertheless, if the 
 rash be very profuse, the erythema may overflow the normal 
 confines of the rash and appear upon the back and limbs. 
 In such case, the overflow which extends beyond the natural 
 limits of the rash will be less vivid in colour and will not
 
 TOX^EMIC RASHES 69 
 
 show the wonted tendency to blood-stasis or to the develop- 
 ment of petechial elements. 
 
 Effect on the incidence. A peculiarity of the purpuric 
 rash is that it has a tendency to shield from the invasion 
 of the focal lesions those parts of the skin which it occupies. 
 The evidence on which this conclusion is based is vitiated by 
 the consideration that the favourite situations of the purpuric 
 rash the great flexures and the abdomen are those parts, 
 precisely, which the focal rash habitually shuns. Yet, after 
 giving due weight to that circumstance, the fact remains that, 
 when the purpuric rash is vivid and the focal rash abundant, 
 the immunity to the latter of the area covered by the 
 former is occasionally demonstrated with quite extraordinary 
 distinctness. 
 
 The explanation of this peculiar effect is easy to understand. Pro- 
 nounced purpuric rashes are developed, commonly, before the outcrop of 
 the focal rash ; and, if the capillary circulation in a certain part of the 
 skin has become blocked before the precipitation of the agent which 
 causes the focal lesion, the subsequent precipitation of that agent will 
 thereby be prevented. (See p. 9.) 
 
 It may be mentioned that in rare cases the opposite condition 
 occurs ; that is to say, on that part of the surface where the purpuric 
 rash is most vivid (generally in the groins) the focal rash becomes 
 developed with unwonted profuseness. It is impossible to determine 
 what circumstances unite to secure such a result ; but probably, during 
 the changes in the capillary blood-current consequent upon the 
 incidence of the purpuric rash, changes which range from the normal 
 condition of the circulation down to complete stasis, a favourable, 
 though transient, state of flow happens to occur at a particular time 
 when the active agent in the blood is ripe for precipitation. 
 
 Diagnosis. From the peculiar character and disposition of 
 this rash a case of smallpox may be recognised, sometimes, 
 even before the outcrop of the papules ; or, again, the rash 
 may be a confirmative element in the diagnosis after the 
 focal eruption has appeared. Unfortunately the purpuric 
 rash may be mistaken for the rash of scarlet fever. In severe 
 cases of that disease the erythema exhibits, occasionally, on 
 the fore part of the trunk a character similar to that of the 
 variolous rash ; that is to say, it is dusky in tint, sluggish in
 
 70 THE DIAGNOSIS OF SMALLPOX 
 
 reaction, and flecked with petechue. The distinction between 
 the two lies in the peculiar delimitation of the variolous rash, 
 in its sharp line of demarcation on the thighs, in its greater 
 purpuric tendency, and in the absence of the distinctive signs 
 of scarlet fever. 
 
 Rose rashes. These erythernata are deficient of the 
 fixed character and individuality of distribution of the 
 purpuric rash. Of one kind the seat of election is the 
 trunk of the body (Plate LXXVIL), to which part the invasion 
 may be limited ; but in other cases the rash extends on to the 
 limbs. There is a second type which has a special preference 
 for the limbs, particularly for their distal ends and extensor 
 surfaces. (Plate LXXVIII.) Neither kind of rash has any special 
 affinity for the face, though they may invade it. The presence 
 of one of these rashes is not necessarily a bar to the develop- 
 ment of a purpuric rash in the flexures, but the two sorts do 
 not often corne together. 
 
 When the rose rash is of the more general distribution it 
 consists of a bright erythema, which causes no thickening of 
 the skin, has little or no tendency to cause blood-staining, and 
 is often fugitive. The erythema may be uniform and un- 
 broken, but frequently ft is composite or particulate. In 
 the latter case it may be punctate, like the rash of scarlet 
 fever, or of coarser texture, more nearly resembling that of 
 measles. Sometimes the erythema has a still more broken 
 character, being interrupted by small or large areas of 
 white skin which give the rash an irregular splash-like 
 character. 
 
 The other form of rose rash is limited in most cases to 
 the limbs, in many cases to the arms, and occasionally to the 
 legs only. In typical cases the rash comes up about half-way 
 on to the upper arms, and on the legs extends above the 
 knees. It is made up of red discs with a well-defined edge, 
 in size and colour like the vesicular areola. (Plates LXXIX., 
 Fig. 2, and LXXX.) Below, on the backs of the hands, 
 wrists and forearms, or on the shins and the dorsa of the 
 feet, the spots run together to make a sheet of even redness. 
 AY here the rash creeps round on to the flexor surface of the
 
 TOX.EMIC RASHES 71 
 
 limb, and higher up towards the elbow or the knee, the rash 
 thins out and the elements become distinct. This erythema 
 is commonly darker in tint than the rose rash previously 
 described, and it is less labile. It is apt, therefore, to be 
 somewhat more persistent, and, when it fades, to leave a 
 slight yellow staining of the skin ; but it does not become 
 purpuric. 
 
 In some cases the rash last described has a wider dis- 
 tribution, covers all the limbs, and invades the trunk. (Plates 
 LXXXI. and LXXXII.) Since, therefore, the one kind of rose 
 rash may extend from the trunk and cover the limbs, and 
 the other may spread from the limbs over the body, it is 
 obvious that in some cases the distribution will be indifferent. 
 In most cases it is not difficult, by observing the seat of 
 election of the rash and the character of its elements, to 
 determine to which group it belongs. But the discrimi- 
 nation is superfluous, since both have the same clinical 
 significance. 
 
 Diagnosis. These rashes are a prolific source of confusion. 
 Occasionally they are attributed to scarlet fever, but much 
 more often to measles. The kind last described, which prefers 
 the limbs, should be distinguished from the rash of measles 
 without much difficulty, for their affinities of distribution are 
 opposite. The other kinds, also, have some points of distinction 
 from measles, but these would be of more value were not 
 the temptation to ignore them so often overwhelming. An 
 interrupted erythema, constitutional symptoms suggestive of 
 a specific fever and, as likely as not, suffused eyes or faintly 
 injected conjunctivas, with such a conjunction of symptoms 
 there is a temptation to ignore a discrepancy in the anatomy 
 of the rash and in its distribution. The chief difference in distri- 
 bution is that the variolous rash does not, generally, affect the 
 face ; or, if the face is affected, the rash shows no discontinuity 
 of surface there, and no special choice for the skin behind the 
 ears, and over the temples, and among the hair-roots. The 
 variolous erythema is apt to be irregular in distribution, 
 irregular in the profuseness of its development and in its 
 depth of tint, and lacking in uniformity of composition. It
 
 72 THE DIAGNOSIS OF SMALLPOX 
 
 differs in elementary character from the measles rash, if not 
 on all parts, at least on some ; the erythema being too fine in 
 texture, or too coarse, or too patchy, and the skin affected by 
 it not being thickened or raised. 
 
 Confusion with scarlet fever is less frequent, though the 
 resemblance of the rashes may be closer. The distinction, in 
 fact, in most cases is easy to make by an examination of the 
 mouth and throat and glands.
 
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 PLATE LXXVII. 
 
 A toxaemic variolous erythema, scarlatiniform in type and generalised in distribu- 
 tion. The dark spots represent the focal lesions.
 
 PLATE LXXVIII. 
 
 The figures represent the extensor and flexor surfaces of a forearm bearing a toxEemic 
 variolous erythema, and illustrate the characteristic disposition and appearance of a 
 rash of this type.
 
 X 53 
 
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 CHAPTER XI 
 
 H^MORRHAGIC SYMPTOMS 
 
 THE key to a clear conception of this phase of the disease is 
 to remember that hemorrhage from smallpox is not synony- 
 mous with hsemorrhagic smallpox. 
 
 A patient may be said to suffer from toxic or hsemor- 
 rhagic smallpox when his life is menaced by the toxaemia.* 
 An analogy is furnished by scarlet fever. Cases of that disease 
 are encountered, which are dominated by the constitutional 
 rather than by the local symptoms. Such cases are called 
 toxic cases. They are signalised by a rash which shows a 
 marked aptitude for blood-staining, and they go on rapidly 
 to a fatal issue. They are in contrast with cases in which 
 the angina is pronounced, and death, if it occurs, follows 
 from septic absorption. Those two groups are analogues of 
 hsemorrhagic and confluent smallpox. Haemorrhagic small- 
 pox is toxic smallpox, and in this volume the terms are used 
 indifferently. 
 
 In separating for convenience of description a group of 
 cases which conform to an imaginary type, it must be 
 remembered that the practice is arbitrary. Hsemorrhagic 
 or toxic smallpox has no peculiarity which is essential. No 
 fixed line separates the toxic from the less serious cases, but 
 there is a gradation from the milder cases up to those in 
 which death descends with relentless rapidity. It follows 
 that symptoms of haemorrhage cannot be regarded, as the 
 name hsemorrhagic smallpox would seem to imply, as the 
 
 * It is sometimes convenient, for statistical purposes for example, to use a 
 definition which is more exact. It is then, perhaps, best, in the present state of 
 our therapeutics, to restrict the terms to those cases which are fatal from the 
 toxaemia, or from some condition (such as oedema of the lungs) which the 
 toxaemia has induced. 
 
 73
 
 74 THE DIAGNOSIS OF SMALLPOX 
 
 hall-mark of a peculiar type of disease ; and it will be under- 
 stood that this chapter is devoted to the description, not of a 
 type of disease, but of a group of symptoms. 
 
 Hsemorrhagic symptoms are due, doubtless, to the circu- 
 lation of a specific poison or toxin. The sequence is not 
 peculiar to smallpox; it occurs in cases of haemorrhagic 
 diphtheria, of toxic scarlet fever, of pneumonic plague, and 
 from some kinds of snake-bite poisoning. The toxins inci- 
 dental to those different maladies differ in their ability to 
 cause haemorrhage ; that of smallpox is peculiarly apt, and 
 death from the variolous toxaemia is almost always preceded 
 by haemorrhagic manifestations. 
 
 The haemorrhage itself is seldom dangerous. It is im- 
 portant as an expression of the operation of the toxin. Yet, 
 from case to case, the toxin operates with unequal effects. 
 Its precise action will depend, not only upon the dose, but 
 also upon the patient and his vital weaknesses. In one case 
 the bleeding will be chiefly from the air-passages, in a second 
 there will be haematuria, in a third cutaneous haemorrhage 
 only. Moreover, of two patients equally severely poisoned, 
 in one case the haemorrhagic symptoms will be masked, in 
 the other they will be pronounced. The significance of the 
 different haemorrhagic symptoms will depend, therefore, not 
 only upon the kind and degree of haemorrhage, but equally 
 upon the other symptoms with which they are associated. 
 Many patients, not desperately ill, exhibit haemorrhagic 
 symptoms of a sort ; and, indeed, in almost all cases of 
 smallpox there can be discerned the trail of the special 
 faculty to bleed. 
 
 Post-toxaemic haemorrhage. -- The extravasations are 
 secondary, it may be supposed, to some damage suffered by 
 the vascular endothelium or to some injurious action of the 
 toxin on the vascular mechanism. Such damage can be 
 effected only while the toxin is circulating in the blood ; that 
 is to say, during the toxaemic fever. Yet the effect of the 
 damage, the liability to haemorrhage, may remain with the 
 patient even after the elimination of the toxin has been fulfilled. 
 Patients, therefore, who have passed through the toxaemia
 
 H.EMORRHAGIC SYMPTOMS 75 
 
 and entered upon the separate hazards of the secondary fever, 
 may still exhibit signs of the haemorrhagic tendency. A slight 
 injury, which would be innocuous in health, may cause 
 a blood-effusion in a patient whose vessels are already 
 weakened by the disease. Thus patients with smallpox are 
 exceptionally liable to bruises, even during the period of 
 suppuration. 
 
 Another sign is so common that it may be observed in 
 almost every case. The focal lesion, it will be seen presently, 
 is an injury so potent that in the severer cases it may 
 determine a bloody extravasation about itself long before its 
 maturity. When the patient is less severely poisoned, a 
 premature lesion does not have that effect ; but as the lesion 
 ages, and grows, and suppurates, and destroys the tissue about 
 it, the stimulus gathers force ; and at last, even in the milder 
 cases, excites an extrusion of haemocytes from the vessels, 
 which may be unnoticed at the time, but leaves its record 
 hi the pigmented area which surrounds the scar. (Plates 
 LXXL, Fig. 2, and LXXIIL, Fig. 1.) 
 
 In some cases the extravasation is obvious before the 
 pustule has become encrusted. It is not uncommon in cases 
 of confluent smallpox, more especially on the arms and legs 
 where the stimulus of the lesion is supplemented by the 
 movements of the limb, to see some of the pustules with 
 blood-stained contents. (Plates LXXXIII. and LXXXIV., 
 Fig. 1.) Occasionally these haemorrhagic pustules are dis- 
 played, even in cases of discrete smallpox, over a considerable 
 area of the body. 
 
 Yet all these tardy evidences of the tendency to bleed are 
 wholly devoid of significance. They are but the foot-prints 
 of an illness which has passed. 
 
 Toxaemic haemorrhage. Other factors being equal, the 
 greater the dose of the toxin, the earlier and the more readily 
 will become manifest its capacity to provoke haemorrhage. 
 Therefore a haBinorrhagic symptom, developed during the 
 course of the toxaernic fever, assumes at once a certain 
 clinical significance. 
 
 Yet many of these manifestations are not of serious omen.
 
 76 
 
 It is a general rule that bleeding from internal structures or 
 surfaces is more serious than external extravasations. Some 
 kinds of cutaneous haemorrhage are, in fact, so common that 
 they may be regarded as ordinary symptoms of the toxaemia 
 One such symptom is the exhibition of the purpuric or 
 petechial rash, which was described in Chapter X. and will 
 be referred to also in a later chapter. Petechiaa, again, not 
 specially grouped, but scattered fortuitously and often 
 sparsely over the surface, are apt to appear on the skin of 
 the trunk and upper parts of the limbs with all the severer 
 sorts of toxaemia, especially in the cases of children. 
 
 A graver, but not necessarily a fatal sign is the develop- 
 ment of small round or oval extravasations, clear-cut and 
 counter-sunk (Plate LXXXIV., Fig. 2.) In this instance, also, 
 children are the favourite subjects. These spots are seldom 
 bigger than a split pea. Their colour ranges from violet to 
 black, according to the depth of tissue occupied. Usually 
 they are sparingly developed. They choose the parts 
 most apt to display petechise, with which they are often 
 associated. 
 
 Of more serious omen still are cutaneous extravasations 
 occurring in streaks and patches. Such blotches are irregular 
 in outline, and inconstant in depth of tint. They may appear 
 on any part of the skin, and may attain a considerable size. 
 If, in a case of toxic smallpox, an erythematous rash' is 
 developed, it very readily becomes streaked or mottled by 
 such areas of discoloration. Yet a toxaemic rash, present- 
 ing such a character, is not necessarily of the most serious 
 significance unless the colour is very dark, that is to say, deep 
 purple or black. (See also Chapter XIII., p. 98.) Haemor- 
 rhage of this sort is to be regarded the more seriously when 
 not excited by a coincident erythema. 
 
 Toxic smallpox causes the blood to coagulate imperfectly. 
 Hence a scratch, or a trifling abrasion of the skin, is very apt 
 to be marked by a continuous or interrupted oozing of blood 
 from the broken surface. 
 
 Extravasations about the vesicles or papules are among 
 the most frequent of hseinorrhagic symptoms.
 
 ILEMORRHAGIC SYMPTOMS 77 
 
 The areola is more prone to be affected than the lesion 
 itself. Sometimes it is only to be observed that the colour 
 of the areola is immobile ; and when it has faded, that it 
 has left its record in blood-pigment. But when the vessels 
 are more impaired, the areola acquires a violet or purple tint 
 from the excessive effusion of blood. (Plate LXXXV.) Blood- 
 stained areolse may be developed over the greater part of 
 the cutaneous surface, but are seen most often on those 
 parts of the body, such as the shins, where the circulation 
 is slow. 
 
 Either alone, or in conjunction with the staining of the 
 areola, an extravasation may occur into the vesicle itself; and 
 the latter is the more serious sign of the two. The effusion 
 may be directly into the cavity of the vesicle, which turns 
 black from the blood which distends it. But that event is 
 relatively uncommon > and at the most but few of the vesicles 
 are so affected. Generally the effusion takes place into the 
 tissue at the base of the vesicle. The colour and ocular 
 definition of the effused blood are then obscured by the 
 superjacent lesion; and unless the extravasation is very pro- 
 nounced, it looks indistinct, as though seen through a bluish 
 haze, like a stained object out of focus in the microscope. 
 (Plate LXXXV., Fig. 2.) These subvesicular effusions are among 
 the commonest of the hfemorrhagic signs of the toxemia. In 
 some cases and in many of these the toxsemic fever is not 
 especially serious only a few vesicles are affected ; but at the 
 worst the extravasations are very prominent and cover the 
 patient from head to foot, obscuring the whole character 
 of the rash. It must be remembered that the number 
 and prominence of these extravasations are not sure guides 
 to the probable issue, and that in many cases of toxic 
 smallpox, fatal in the vesicular stage, the sign is relatively 
 inconspicuous. 
 
 The papules are not so liable as the vesicles to become the 
 foci of haemorrhagic extravasation. The papule and the 
 papular areola sometimes become blood-stained ; less fre- 
 quently, the papule becomes capped with blood. (Plate 
 xci.)
 
 78 THE DIAGNOSIS OF SMALLPOX 
 
 The significance of a hemorrhagic effusion varies in pro- 
 portion as it is spontaneous, and not accidental or factitious. 
 Subcutaneous haemorrhage is, therefore, not necessarily of 
 serious omen. Not infrequently a bruise can be traced to 
 some injury, and all patients with smallpox bruise easily. 
 But the significance of the bruise increases with the dispro- 
 portion between cause and effect ; and multiple bruise-like 
 effusions are sometimes the most prominent feature of a case 
 of toxic smallpox. In many cases subcutaneous extravasa- 
 tions occur which are not so pronounced as to cause dis- 
 coloration of the skin ; but they can be discerned beneath 
 the surface as indistinct vein-like markings. 
 
 A favourite situation for effusion of blood is the orbit. 
 The effusion may even be so extensive as to cause distinct 
 proptosis of the eyeball. Still more common is extravasation 
 into the ocular conjunctiva. The effusion assumes a tri- 
 angular shape, the base of the triangle lying against the 
 cornea. Conjunctival haemorrhage may be one-sided or 
 double. It may be developed both on the inner and on the 
 outer side of the cornea, and in the worst cases the whole of 
 the conjunctiva becomes filled with blood. Conjunctival 
 hemorrhage, unless very pronounced, is not to be regarded 
 with despondence. It is among the least serious of the 
 hemorrhagic symptoms. 
 
 While hemorrhage from within is, in the main, to be 
 regarded more seriously than extravasations on the surface, 
 the evidence must still be used with discrimination. Perhaps 
 the most common of these symptoms is uterine hemorrhage. 
 But all forms of the toxemia have a tendency to induce 
 prematurely the menstrual flow ; and if the patient is preg- 
 nant, a toxemia of even moderate severity is capable of 
 causing abortion. It is not surprising, therefore, that 
 when women get toxic smallpox, repeated or continuous 
 uterine hemorrhage should be the rule. Again, epistaxis 
 is a common symptom of toxic smallpox. But when 
 the patient is subject to epistaxis, or is a child, the 
 symptom is to be regarded differently from repeated or 
 continuous bleeding from the nose when the patient is a
 
 H.EMORRHAGIC SYMPTOMS 79 
 
 stranger to that symptom. Similarly, a little oozing from 
 the gums need not be taken very seriously ; but a dark bloody 
 extravasation into the mucous membrane of the fauces, the 
 palate, and the root of the tongue, is a common and character- 
 istic symptom in toxic cases. 
 
 With rare exceptions, only in toxic cases do other kinds 
 of internal haemorrhage become prominent. Haemoptysis is 
 common ; generally it comes on late in the toxaemia, and is a 
 sign of congestion or oedema of the lungs. Haeinatemesis 
 occurs with frequency in cases in which it cannot be ascribed 
 to the swallowing of blood poured out from .the nose, or 
 throat, or lungs. Melaena is less common, but by no means 
 rare. A symptom, one of the most frequent of all, is haema- 
 turia. In this connection the word does not imply merely 
 the passage of " smoky " urine, but the voiding of fluid of the 
 colour of port wine. 
 
 Prognosis. Extravasation into the faucial mucous 
 membrane, severe or continuous haemoptysis, hsematemesis, 
 haematuria, continuous epistaxis, multiple spontaneous 
 bruises, purple cutaneous extravasations, numerous extravasa- 
 tions about the focal lesions, when there is a combination of 
 some of these symptoms, the patient very seldom recovers. 
 But the significance of any one of them is much reduced if it 
 stands alone, and it is seldom safe to forecast the issue from 
 the hsemorrhagic symptoms only. This is still more true if 
 the haemorrhage is less pronounced, or of the less serious 
 kinds ; in such cases, and they are many, all hangs upon the 
 nature of the coincident symptoms. 
 
 CASES WITH SYMPTOMS OF HEMORRHAGE 
 
 The following cases have been selected to illustrate the 
 variety of haemorrhagic symptoms which may be displayed, 
 the variety in the course of the illness, and the variety of 
 result. The collection does not reflect the frequency with 
 which cases of different degrees of severity occur in practice, 
 but indicates a scale of severity, any note of which may be 
 struck by a particular case.
 
 80 THE DIAGNOSIS OF SMALLPOX 
 
 Case I. Confluent smallpox tctf/t snbvesicular haemorrhage 
 Recovery. A. H., a man aged 38, was stated to have been vaccinated in 
 infancy but had no cicatrices. During the first two days of illness the 
 symptoms were of so moderate a character that the patient kept his bed 
 against his inclination. The outcrop of the papular rash occurred on 
 the third day. Thereafter, there was a great deal of prostration and 
 considerable toxsemic pyrexia ; by the sixth day of illness the patient 
 was very ill and highly delirious. The rash was confluent on the face, 
 but not of excessive numerical severity. The lesions were soft, and slow 
 in evolution ; the areolae were of a dull red colour and sluggish in 
 reaction, and on the legs were for the most part altogether immobile. 
 When the rash had become vesicular, it was very noticeable that 
 haemorrhage had occurred in the bases of a large number of the vesicles. 
 The purplish staining of the lesions, so caused, was apparent on the face, 
 but was more conspicuous on other parts of the body. It occurred on 
 the trunk, arms, wrists, and legs, but was worst on the feet. In some 
 parts only at intervals was a vesicle stained, but in other places a large 
 proportion of them. The general effect was that, especially on the limbs, 
 the rash was extensively discoloured. There were no other haemorrhagic 
 symptoms, and on the eighth day of illness the other symptoms abated. 
 The succeeding fever of suppuration was not very severe, and the 
 patient made a good recovery. 
 
 Case II. Toxic smallpox Subvesicular haemorrhage Death from 
 oedema of the lungs. C. W., a man aged 32, was vaccinated in infancy 
 and had two cicatrices. He died on the eleventh day of illness. The 
 toxaemic symptoms were pronounced, but not of the first severity. 
 Towards the close of the illness the patient became delirious. The out- 
 crop occurred on the fourth day. The rash was extremely profuse, and 
 on the face was superconfluent. In its earliest stage it was of a vivid 
 red colour, which could be discharged only imperfectly by pressure and 
 on the legs was quite immobile. The papules were soft ; and when the 
 lesions became vesicular, they were still limp and were slow in 
 evolution. On the legs subvesicular haemorrhage developed extensively ; 
 the backs of the feet and the shins were covered with plum-coloured 
 vesicles. The ulnar sides of the forearms became similarly affected, 
 though the colour in those situations was not quite so deep as on the 
 legs. There were no other hiemorrhagic symptoms. On the ninth day 
 of illness the rash on the face had become pustular, the pustules being 
 small and distinctly modified. But on other parts of the body the 
 vesicles showed no sign of modification, and presented the same flat, 
 limp character as before. In some places the cuticle had peeled off, and 
 large raw surfaces were so exposed. Towards the close of the illness 
 the patient developed oedema of the bases of both lungs, and rapidly 
 became cyanosed and died. 
 
 Case III. Toxic smallpox Death on the tenth day of illm.<s 
 from pneumonia. P. G., a boy aged 8, unvaccinated, fell ill with 
 symptoms of gradually increasing severity, and became delirious on
 
 H.EMORRHAGIC SYMPTOMS 81 
 
 the third day of illness. The patient was quiet in his delirium, but 
 it persisted until his death. The focal rash appeared on the third 
 day, and was very abundant. The colour was vivid and not very 
 labile. When the rash attained the vesicular stage, many of the lesions 
 presented a purplish subvesicular staining; this appearance was most 
 noteworthy on the thighs. The first decisive sign of the gravity of 
 the illness was a fetid odour of the breath, first noticed on the fifth 
 day of illness. But, earlier, some small pink petechiae had been 
 noticed scattered about the body, and also a few larger cutaneous 
 hemorrhages about a tenth of an inch across ; most of the latter were 
 violet in colour, but two of them were purple-black. On the sixth 
 day of illness the boy began to spit up blood-stained mucus, and there 
 were some signs of redema of the lungs. A bruise half an inch 
 across appeared on the forehead. During the succeeding days the 
 patient seemed better. The odour of the breath became inoffensive, 
 the expectoration ceased to be blood-stained, and there was normal 
 evolution of the eruption. But in the end the child developed 
 pneumonia and died. 
 
 Case IV. Tofic smallpox (Edema of the lungs Recovery. 
 It has been pointed out that, though the symptoms of haemorrhage 
 are an expression, they are not necessarily a measure of the severity 
 of the toxtemia. In this case these symptoms were conspicuous ; but 
 though the other toxa;mic symptoms were by no means insignificant, 
 the case was exceptional, not so much because the patient under those 
 circumstances survived, as because she survived also the pulmonary 
 complication which is so generally fatal. On the third day of 
 her illness the patient, L. B., aged 27, unvaccinated, developed 
 a papular rash which afterwards became confluent. On the legs many 
 of the areolaj became blood-stained ; and here and there about the 
 body and limbs, hemorrhage occurred in the bases of some of the 
 vesicles. On the sixth day of illness there was an attack of epistaxis. 
 Some extravasations appeared on the hard palate, and the fauces 
 became black and foul from effusion of blood into the mucous mem- 
 brane. On the seventh day a large conjunctival haemorrhage de- 
 veloped in the left eye, and the patient began to cough up blood- 
 stained mucus. She continued to expectorate large quantities of 
 blood-stained fluid, but on the tenth day of illness the secretion 
 ceased to be blood-stained. Thereafter, the oedema of the lungs cleared 
 up, the patient developed a normal secondary fever without further 
 complications, and made a good recovery. 
 
 Case r. Toxic smallpox Death on the tenth day from oedema, 
 of the lungs. A. A., a woman aged 38, had been vaccinated in infancy 
 but had only one very small cicatrix. The onset of the illness was very 
 sudden, the pain violent and lasting, and the prostration extreme. 
 Except for a few hours during the night of the sixth day, the mind 
 remained clear throughout the illness. The outcrop occurred on the 
 third day, and the rash was abundant. The colour of the papules and 
 G
 
 82 THE DIAGNOSIS OF SMALLPOX 
 
 areolaj was dark red, and was imperfectly mobile. The subsequent 
 evolution of the eruption was slow and imperfect, the vesicles, when 
 formed, being flat and limp, and showing no sign of suppuration until 
 shortly before death. On the fourth day of illness a petechial rash 
 appeared in the groins and armpits ; additionally, many petechue and a 
 few larger extravasations were scattered irregularly about the trunk 
 and upper arms. Epistaxis set in on the sixth day : the patient was 
 subject to this symptom, but the bleeding was unusually severe and 
 continuous. About the same time, uterine haemorrhage developed ; and 
 it was noticed also that the focal rash displayed some subvesicular 
 haemorrhage. On the eighth day there was some haemoptysis. On the 
 following day the patient rallied, and the epistaxis ceased. But she 
 had developed oedema of the lungs, and on the tenth day of illness was 
 expectorating large quantities of watery fluid. The respiration increased 
 in rapidity, and the patient became cyanosed and died. 
 
 Case VI. Toxic smallpox Profuse jxipular eruption Death on 
 the seventh day of illness. J. A., a married woman, aged 23, un- 
 vaccinated, fell ill with symptoms of gradually increasing severity. On 
 the day of onset she got up in the morning, but returned to bed later. 
 On the day following she was worse, the prominent symptoms being 
 vomiting, headache, pains in the loins and general prostration ; but the 
 symptoms were not of unusual severity. The outcrop occurred on the 
 third day of illness. On the day following the outcrop abortion 
 occurred, the pregnancy being of two months' date. During this time 
 the prostration had become extreme ; and on the sixth day of illness 
 the patient was collapsed, looked bloodless, and presented a facies 
 typical of severe forms of toxic smallpox. The mental faculties were 
 perfectly clear. The odour of the breath was horribly fetid. Except 
 some uterine haemorrhage following the abortion, the first haemorrhagic 
 symptom which had been noticed was a bruise, which formed on the 
 left hand after a slight blow sustained on the fifth day of illness. 
 During the night of that day, also, there had been severe uterine 
 haemorrhage. On the sixth day there was extensive extravasation of 
 blood into the fauces, the throat and palate becoming black. The lips 
 and teeth were covered with bloody crusts, and there was conjunctival 
 haemorrhage in both eyes. There was a slight abrasion on the forehead, 
 from which blood oozed. Across the loins was a band, a few inches 
 wide, composed of numerous petechiae lying in a dusky erythetnatous 
 matrix ; but that affection of the skin was confined to that situation, and 
 did not invade the more usual situations of the toxaemic petechial rash. 
 Some petechiae were scattered irregularly over the chest, abdomen and 
 legs, and mingled with them were a few somewhat larger extravasations, 
 ranging in colour from violet to purple-black. On the arms there 
 were several small, indistinct, vein-like, subdermal extravasations, in 
 size from half-an-inch to one inch across. In addition, there was a 
 large bruise on the back of the left hand and another on the right hip. 
 The papular rash was very profuse. On the face the papules were pale
 
 H.EMORRHAGIC SYMPTOMS 83 
 
 and very hard to distinguish. Elsewhere they were more conspicuous, 
 but everywhere soft and ill-defined. A few were blood-capped. 
 Throughout the illness no sign of vesiculation was observed in the 
 lesions. On the evening of the sixth day there was again profuse 
 hemorrhage from the uterus, which continued until death. Early in 
 the morning of the seventh day of illness the patient complained of 
 pain over the heart, became cyanosed and pulseless, and died. She was 
 conscious until within a few minutes of death. 
 
 Case VII. Toxic smallpox Scant;/ pipulnr rash Death on the 
 seventh day of illneas. M. J. H., a girl aged 12, was vaccinated in 
 infancy but presented only one very small cicatrix. The focal rash was 
 first observed on the fifth day of illness, but the rash was composed 
 only of a few papules, and there were none except on the forehead. 
 Even at the time of death the lesions had not materially increased in 
 number, and had not become vesicular ; but by that time a few papules 
 could be detected on other parts of the body besides the face. The ill- 
 ness did not begin very suddenly. On the day of onset the child got 
 up in the morning but, feeling unwell, had to go back to bed. She 
 complained of headache, and of pain in the back and legs ; and there 
 was some vomiting. On the second day of illness there were some 
 attacks of shivering ; and during that and the succeeding days the child 
 became progressively worse, and was delirious at night. On the third 
 day of illness there were a few attacks of epistaxis, and some blood was 
 vomited. On the fourth, some petechue were noticed about the body. 
 A large number of these soon made their appearance ; yet they were 
 not so distributed as to suggest a toxsemic petechial rash, but were 
 scattered haphazard about the trunk, the shoulders, and the upper parts 
 of the thighs. Here and there, scattered with the petechiae, were a few 
 small purple extravasations, in size near that of a pea. Vomiting of 
 altered blood continued to occur at intervals, and on the sixth day 
 blood became effused into the conjunctivae of both eyes, and a large 
 effusion occurred deeply in the left calf. The pulse became very rapid, 
 and death took place early on the seventh day of illness. The delirium 
 continued to the end. 
 
 Case VIII. Toxic smallpox Death on the sixth day of illness 
 before the outcrop. H. B., a man aged 25, unvaccinated, suffered the 
 customary symptoms of onset and the succeeding prostration. On the 
 fourth day of illness a petechial toxaemic rash appeared. This covered 
 the chest and abdomen, groins and axillae, and extended on to the 
 shoulders and upper parts of the arms, and on to the inner and front 
 part of the thighs. The rash extended also across the loins. The 
 affected parts rapidly gained depth of tint and became the seats of 
 innumerable petechiae ; at the close of the illness that portion of the 
 skin presented one continuous sheet of violet haemorrhagic discolora- 
 tion. A few irregular patches of discoloration developed also on the 
 forearms, hands, and legs ; in the last situation, chiefly along the course 
 of the internal saphenous vein. Conjunctival haemorrhage developed in
 
 84 THE DIAGNOSIS OF SMALLPOX 
 
 both eyes. On the fifth day of illness the patient began to spit blood, 
 and the fauces became intensely discoloured from extravasation into 
 the mucous membrane. On the sixth day, a few hours before death, 
 there was hsematuria. No focal rash appeared, with the exception that 
 one small vesicle was noticed on the back of the right hand. 
 
 Case IX. Toxic smallpox in a neiv-born infant Death on the second 
 day of illness. E. B., a female, the child of a variolous mother, dis- 
 played no abnormal symptom during the first four days of life. On the 
 fifth day she took food badly and seemed ailing.. On the following day 
 the child was weak, and had cold extremities and pale lips. At 5 a.m. 
 some red frothy blood was vomited. At 11.30 a.m. blood was vomited 
 for the second time and in considerable quantity. At 1.30 p.m. the 
 child vomited blood for the third time. She died suddenly half-an-hour 
 later. No other hamiorrhagic symptom was observed during life, and 
 there was no focal rash. At the autopsy, signs were observed which 
 were characteristic of death from toxic smallpox. The child was 
 vaccinated on the day of birth, and at the time of death displayed the 
 first signs of a successful vaccinal reaction.
 
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 PLATE LXXXIV. 
 
 Fig. 1. This is a reproduction on a large scale of a part of the photograph 
 rendered in the last print. The intrapustular and the extramural 
 extravasations are more clearly distinguished (i and a). In many 
 instances the distinction was displayed by the same lesion, a lighter 
 ring separating the black centre from the peripheral zone. 
 
 Fig. 2. The thighs of a patient dead of haemorrhagic smallpox. Death 
 occurred before the outcrop of the focal rash. The black spots seen in 
 the print represent circumscribed bloody extravasations into the skin, 
 black, purple, or violet in colour. Above the left knee was a thin black 
 line encircling the thigh. This was a linear extravasation, and was 
 cvi >kcd by the pressure of a garter.
 
 PLATE I.XXXIV.
 
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 CHAPTER XII 
 
 H^MORRHAGIC OR TOXIC SMALLPOX 
 
 So protean is the disease, and especially this graver phase ot 
 it, that but for the teaching of experience some of its manifold 
 types might be taken for distinct disorders. But the types 
 merge into one another. Toxic smallpox is of one kind 
 though of many degrees ; and perhaps there is more to be 
 lost in clearness than can be gained in convenience by 
 attempting a classification which shall lock off sections 
 in the stream of cases. The features common to all cases, 
 or peculiar to some, will therefore be grouped together and 
 discussed under appropriate headings.* 
 
 Constitutional symptoms. The description of the tox- 
 rcmic symptoms, given in Chapter IX., would lack vigour 
 if applied to these graver cases. The onset may be more 
 
 * Many authors follow Curschmann (Ziemssen's Cyclopaedia) in his classifi- 
 cation or terminology. In descriptions of smallpox it is a common practice to 
 distinguish, under the names of " initial illness " or " prodromal stage," that 
 part of the toxaemic fever which occupies the interval between the onset of 
 illness and the outcrop of the focal rash. That such a distinction is arbitrary is 
 of little moment in the description of ordinary cases. But Curschmann pursues 
 it in the discussion of toxic smallpox, when- it becomes the source of some 
 confusion. He divides toxic cases into two groups, the first of which he calls 
 " purpura variolosa," and defines as ' the initial stage of variola which has 
 become haemorrhagic," and the second " variola haemorrhagica pustulosa," 
 under which head he includes cases in which the focal lesions become foci of 
 haemorrhage. Unfortunately these divisions are neither all-embracing nor 
 mutually exclusive. And the terms themselves are liable to be misunderstood. 
 For on account of the modern limitation in meaning of the English word 
 "pustule," the term "variola haemorrhagica pustulosa" is apt to be taken to 
 refer to cases in which haemorrhage occurs during the pustular stage of the 
 disease ; cases which, though falling strictly within Curschmann' s definition, 
 are not cases of toxic smallpox (see p. 75). Neither is the term "purpura 
 variolosa " free from objection, because it is liable to be applied to cases in 
 which a purpuric toxaemic rash is developed ; and such cases, again, are not in 
 general toxic cases. 
 
 83
 
 86 THE DIAGNOSIS OF SMALLPOX 
 
 sudden, the pains more acute ; and the collapse is more 
 profound. Yet it would be a great mistake to suppose that a 
 fatal toxaemia is always, or even generally, ushered in very 
 suddenly and by symptoms of unwonted severity. Perhaps 
 in most cases one is not led at first to suspect the gravity ot 
 the illness which is about to develop ; and it is not until the 
 second or third or even fourth day of illness that the full 
 severity of the symptoms becomes unmasked. On the other 
 hand, it must be remembered that alarming symptoms are not 
 necessarily the prelude to a fatal, or even to a serious, illness. 
 It will be understood that the description of an illness 
 of the more serious kind will fit some cases in which the 
 issue is never in serious doubt ; and at the same time will 
 mark a standard to which some cases of toxic smallpox 
 never attain. 
 
 Pain. The pains, in some of these cases, are of extra- 
 ordinary severity. The head may feel as though the skull 
 were opening and shutting; the lumbar pain may be com- 
 pared to a sensation as of the grinding together of the bones 
 of the pelvis. These pains are an early developed and a 
 persistent symptom, so that a patient may not be free ot 
 them until the natural end of the toxsemic fever, if death be 
 delayed so long. 
 
 Prostration. An impressive feature of these cases, though 
 one shared by all cases marked by a severe toxaemia, is the 
 excessive prostration of the patient. The prostration develops 
 with a rapidity corresponding to the more or less sudden 
 onset of the illness, but is not at its height until the lapse 
 of the first two or three days. It is then marked by a loss of 
 tone of the whole muscular system. 
 
 On the face this symptom impresses a very characteristic 
 appearance which, once observed, is not difficult to recognise. 
 (Plates LXXXVI. and LXXXVII.) The relaxation of the muscles 
 of expression makes the patient look dull and apathetic. 
 The features are immobile, the lines of expression obliterated, 
 the cheeks relaxed. The lips are full and parted, dry, with 
 sordes on them, or perhaps encrusted with dry clouts of 
 blood. The skin may be flushed or pale. The eyelids droop,
 
 H^MORRHAGIC OR TOXIC SMALLPOX 87 
 
 and it seems to be an effort to lift them ; yet, when the lids are 
 raised, the eyes look bright and shining. (Plate LXXXVIII. and 
 LXXXIX., Fig. 1.) The ocular muscles share in the symptoms, 
 and the patient is apt to follow a moving object by a movement 
 of the head rather than of the eyes. When he is addressed, 
 it is seen that his faculties are clear ; but he rouses himself 
 with an effort, answers with deliberation, and relapses into 
 apathy. Except that he breathes easily, he looks like a man 
 who has just undergone a great and sustained physical exer- 
 tion ; like a runner after the race, self-centred, absorbed in 
 the attempt to renew his exhausted powers. 
 
 With a prostration so profound, it is not surprising that 
 the course of the illness may be interrupted by attacks of 
 collapse, during which the patient displays a clammy skin, 
 cold extremities, a feeble pulse, and perhaps some cyanosis. 
 Such a condition is liable to be -brought about by some effort, 
 little enough in itself, perhaps, but disproportionate to his 
 enfeebled powers. Even the less serious forms of toxsemic 
 fever are not infrequently marked by symptoms of collapse 
 when the patient has overtaxed his capacity for exertion. 
 Sometimes the heart-failure is still more profound, and is 
 signalised by cardiac pain and a fluttering pulse. From such 
 an attack of syncope the patient may rally, or it may prove 
 rapidly fatal. 
 
 In exceptional cases the aspect which has been described 
 is concealed by the anxiety and distress caused by the 
 intensity of the poisoning. (Plate LXXXVIII.) The stimulus of 
 an excessive dose may, indeed, be such as to mask all the pros- 
 tration on which that aspect depends ; and the patient may 
 exhibit a deceptive capacity for exertion, until he collapses 
 upon the brink of death. 
 
 Mental symptoms. The usual mental symptoms are 
 persistent sleeplessness and an unnatural clearness of the 
 intellect, so that the patient shall miss nothing of his suffer- 
 ings. In some cases the mind becomes clouded, or there is 
 delirium ; but generally only towards the close. Yet, with 
 children, nocturnal delirium is common earlier in the illness. 
 
 Pyrexia. From case to case the curve of temperature
 
 88 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 presents considerable variation. In some cases, and those 
 generally the worst, a low temperature prevails, and the 
 thermometer may never record 100. In other cases, especi- 
 ally those in which life is most prolonged, a high temperature 
 is the rule. (Charts ix. and x.) This inverse proportion 
 between the height of the temperature and the severity of the 
 
 104 
 
 103' 
 
 102* 
 
 101' 
 
 ioo 
 
 99' 
 
 98' 
 
 9T> 
 
 UNRECORDED 
 
 CHART ix. Toxic SMALLPOX. 
 TEMPERATURE Low. 
 
 CHART x. Toxic SMALLPOX. 
 TEMPERATURE HIGH. 
 
 attack is common both to toxic smallpox and to toxic scarlet 
 fever, though with toxic scarlet fever the low temperature is 
 very much less common. With smallpox, besides, discrepancies 
 are common in similar cases, so that the thermometer is not 
 of much use in forecasting the probable course of the ill- 
 ness. Even when the fever runs high, the end may be
 
 H.EMORRHAGIC OR TOXIC SMALLPOX 89 
 
 preceded by a fall of temperature. On the other hand there 
 may be terminal hyperpyrexia. (Charts XL and xn.) 
 
 When the illness is protracted, it may happen that the 
 
 107' 
 
 106' 
 
 105' 
 
 10+' 
 
 103' 
 
 102' 
 
 101' 
 
 100' 
 
 99' 
 
 98' 
 
 97 
 
 UNR 
 
 
 CHART xi. Toxic SMALLPOX. 
 Low TERMINAL TEMPEHATVHE. 
 
 CHART xn. Toxic SMALLPOX. 
 HIGH TERMINAL TEMPERATURE. 
 
 patient will survive the onset of the eruptive fever. In such 
 a case, as in most cases of confluent smallpox, the distinction 
 between the two febrile states may be indicated on the chart 
 by a dip in the curve of temperature. (Chart xm.) But
 
 90 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 frequently this break in the curve is obliterated, either by 
 the febrile effect of some complication, or else by the blending 
 of the two fevers. 
 
 CHART xm. Toxic SMALLPOX. TOXJ-:MIC PYREXIA DISTINCT 
 
 FKOM SUPPCRATIYE. 
 
 Factor. There are a few other symptoms of which it is 
 necessary to take account. The most easily observed is a 
 fetid odour of the breath. This sign is very commonly, 
 though not invariably, met with in toxic cases ; on the other 
 hand it is occasionally to be observed in cases which hardly 
 attain to the toxic standard. The symptom will not be con- 
 fused with the foul odour encountered in certain cases of 
 confluent smallpox, which is merely an emanation from the 
 suppurating skin. And the fetor, probably, does not arise
 
 ILEMORRHAGIC OR TOXIC SMALLPOX 91 
 
 from the foul condition of the throat which occurs in some 
 cases of toxic smallpox owing to extravasation of blood into 
 the mucous membrane; for the foetor may be observed in 
 cases in which the throat is unaffected. The odour seems to 
 be an exhalation from the lungs, arising from certain changes 
 in the blood. It is a sickly odour, unique in the catalogue ot 
 nasty smells, and a breath of it, once inhaled, will dwell for 
 ever in the recollection. The sign is often the first danger 
 signal displayed in the course of the illness. 
 
 Albuminuria. Albuminuria may occur as an early and 
 transient symptom of more than one of the specific fevers, 
 and it is met with very frequently in cases of confluent 
 smallpox. In toxic cases it is especially common and con- 
 spicuous, even when unassociated with hiernaturia. 
 
 Enlargement of the liver. A less constant symptom than 
 the last is a rapid and painless enlargement of the liver. 
 Like albuminuria, this symptom is liable to attend, not only 
 the toxic, but also all the severer forms of smallpox. The 
 enlargement becomes perceptible towards the end of the 
 toxsemic fever, and continues its progress during the first 
 part of the fever of suppuration. But in toxic cases the 
 symptom may be apparent earlier in the illness and become 
 very pronounced. Therefore, when other signs are indistinc- 
 tive, some importance attaches to the perception of the liver's 
 edge, one or two fingers' breadth below the cartilages, moving 
 downwards from day to day. Sometimes the spleen is 
 enlarged and perceptible to the touch, but far less frequently 
 than the liver. 
 
 Termination. Patients who die of hsemorrhagic small- 
 pox do not die of haemorrhage. The prostration which they 
 suffer is evidence of a disturbance of the heart which is 
 often so profound as to be fatal. Those who are killed by 
 the toxaemia die, almost invariably, either from heart-failure, 
 or from a common and fateful complication, oedema of the 
 lungs. 
 
 (Edema of the lungs takes time to develop and to kill. 
 Heart-failure, therefore, is the cause of death when the 
 disease kills quickly. The end may be sudden from syn-
 
 92 THE DIAGNOSIS OF SMALLPOX 
 
 cope ; or its approach may be more gradual, and marked 
 by a failing pulse, increasing pallor, and cyanosis. (Cases 
 vi. and vii., Chapter XL) 
 
 In the more protracted cases heart-failure may be still 
 the cause of death. But more often the lungs become en- 
 gorged and sodden, and the patient is likely to expectorate 
 quantities of clear or blood-stained fluid and to die water- 
 logged, drowned in his own secretion. Even though the 
 patient survive this condition, it may be only to die of 
 pneumonia. (Cases IL, in. and v., Chapter XL) 
 
 Recovery. The frequency of recovery from toxic small- 
 pox will depend upon the definition of the term. If the 
 condition is defined by reference, not only to the haainor- 
 rhagic, but also to the other symptoms, cases of recovery 
 are very exceptional. A patient, for instance, may develop 
 haeinaturia together with certain other less important symp- 
 toms of haemorrhage ; yet he may suffer so little prostration 
 that the issue will be hardly in serious doubt. 'Such cases 
 are met with occasionally, and it would be a misuse of terms 
 to instance them as cases of recovery from toxic or hsemor- 
 rhagic smallpox. 
 
 Though recovery is so exceptional when the patient ex- 
 hibits, not only pronounced hsemorrhagic symptoms, but also 
 excessive prostration, the characteristic facies, or the f cot or 
 oris, yet as a matter of fact such patients often survive the 
 toxaemia. And the termination of that stage of the illness 
 is sometimes very well defined. The pains disappear, if they 
 have lasted so long, the symptoms of collapse pass off, and 
 the patient loses the facies and the sense of prostration 
 which the collapse provoked. But these omens are generally 
 illusory. Death, probably, will soon be brought about by 
 redema of the lungs, which the toxaemia has already en- 
 gendered, or by pneumonia arising out of it. If the patient 
 escape those dangers, the focal rash will be likely to prove 
 fatal. In most of these cases the rash is profuse and is 
 sufficient to kill, in the earliest stage of its suppuration, a 
 patient already worn out by the previous illness. Some- 
 times, however, the patient does not succumb until late
 
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 H^EMORRHAGIC OR TOXIC SMALLPOX 93 
 
 in the secondary fever, and occasionally recovers com- 
 pletely. 
 
 Complete recovery from toxic smallpox is generally 
 attributable to the fact that the rash is of moderate severity 
 only, or is partly modified. It has been pointed out 
 (Chapter IX., p. 63) that a severe toxtemia is not necessarily the 
 prelude to an abundant focal rash ; and that a total loss 
 of immunity to the toxaemia may co-exist with the reten- 
 tion of some immunity to the eruptive fever. It follows that, 
 though with toxic smallpox it is the rule for the rash to 
 be excessive if the patient lives long enough for it to develop, 
 yet in some cases the rash will not be very abundant, 
 and in others will display some degree of modification. 
 (Plate LXXXV., Fig. 1.) It is usually in such circumstances 
 that recovery from toxic smallpox occurs. 
 
 Duration and course. In exceptional cases, which 
 there is no hesitation to class as toxic, life is prolonged far 
 into the secondary fever. But as a rule the patient does not 
 survive beyond the eighth day of efflorescence ; a date which 
 would correspond, in most cases, with the tenth or eleventh 
 day of illness. 
 
 With natural smallpox the onset of suppuration occurs on 
 the fifth day of efflorescence, and by the eighth the eruption 
 has completely matured. With toxic smallpox, also, the 
 course of events in that respect may be not materially different ; 
 that is to say, a patient, dying on the eighth day of efflor- 
 escence, may display a pustular eruption. (Cases n. and 
 in., Chapter XL, and Chart XIIL, p. 90.) But in many other 
 instances life may be prolonged to the same extent, and yet 
 suppuration may hardly become evident. 
 
 Such delay in the advent of suppuration is occasioned by 
 the undue severity and duration of the toxcemic fever. In 
 most cases of toxic smallpox the outcrop occurs at the usual 
 time, that is to say, on the third or fourth day of illness. 
 Yet, as was pointed out in Chapter VI. (p. 42), an excessively 
 severe toxaemia is capable of retarding all stages of the 
 subsequent evolution of the eruption. (Cases v. and vi., 
 Chapter XL, and Chart XL, p. 89.)
 
 94 THE DIAGNOSIS OF SMALLPOX 
 
 The toxaemic fever may be prolonged, also, by a protracted 
 interval between the onset of the illness and the outcrop of 
 the rash (see Chapter IX., p. 62). The outcrop may be post- 
 poned until after the fourth, or fifth, or even the sixth day of 
 illness. A delayed outcrop is a feature of some of the worst 
 cases. (Case vn., Chapter XL) 
 
 On account of this variety in the possible course of the ill- 
 ness, there is no uniformity of clinical aspect about patients 
 who have been ill for the same length of time. Patients 
 even, whose eruptions are of the same age may display con- 
 siderable variety in the character of the rash. 
 
 The worst forms of an illness are generally the least 
 common, and cases of toxic smallpox occur with a frequency 
 which is in inverse proportion to the rapidity of the fatal 
 issue. Most cases are fatal after the seventh day of illness ; 
 and in such, whatever its precise character may be, a 
 pronounced eruption is almost always developed before the 
 end of the illness. 
 
 When the date of death falls between the fifth and seventh 
 day of illness, there is much more inconstancy as to the 
 prominence which the eruption attains. A well-developed 
 vesicular rash may be seen in a case fatal on the fifth day, 
 and but a few scanty papules in a case fatal on the seventh. 
 
 Patients sometimes die before the outcrop. In such cases, 
 for the reasons already set forth, it by no means follows that 
 the illness is of the briefest. (Case viu., Chapter XI.) In the 
 majority of instances the patient does not die before the 
 fourth day. Indeed, death earlier than the fourth day is 
 altogether exceptional ; yet it is possible for the toxaemia to 
 kill in little more than twenty -four hours.
 
 CHAPTER XIII 
 H^MORRHAGIC OR TOXIC SMALLPOX (concluded) 
 
 The focal rash. The clinical character of a case depends 
 chiefly upon the prominence attained by the focal rash. If 
 the eruption is absent or inconspicuous, the case is dominated 
 by the constitutional and hseinorrhagic symptoms; but in 
 most cases, however the illness commenced, the skin affection 
 ultimately usurps the attention, and the disease seems to be 
 almost as much a dermatosis as a constitutional disorder. 
 
 The kind of rash met with in the commonest sort of case 
 has already been described in Chapter YL (p. 40). The rash 
 is profuse ; on the face it is confluent or superconfluent. In 
 its earlier stage it is generally bright red ; occasionally the 
 colour tends to a dusky tint ; it is pale only when the pros- 
 tration is extreme. The papules are soft, and often incon- 
 spicuous individually. The vesicles are flat, flaccid, and slug- 
 gish in evolution. (Plate LXXXIX.) In some cases the cuticle 
 becomes detached, here and there, and blebs are formed con- 
 taming blood-stained serum. 
 
 The capacity of the lesion to provoke effusion of blood 
 increases with its progress in evolution. Many cases in which 
 the rash becomes vesicular are, therefore, distinguished by 
 pronounced hsemorrhagic extravasations about the lesions. 
 (Plate xc.) Yet it must be remembered that the promi- 
 nence which this symptom attains is governed very much by 
 individual idiosyncrasy. In many cases of confluent small- 
 pox, approximating to the malignant type but sustaining no 
 claim to be called toxic, the lesions exhibit, here and there, 
 more especially on the limbs, purplish subvesicular staining or 
 violet-tinted areolae. And there are cases of toxic smallpox 
 in plenty, with well-developed focal rashes, which display 
 hsemorrhagic extravasations of no greater prominence. 
 
 95
 
 96 THE DIAGNOSIS OF SMALLPOX 
 
 When death occurs before the rash has passed beyond the 
 papular stage, even though the papules may have been 
 developed in abundance, haemorrhage about them is generally 
 absent or inconspicuous. Yet of some such cases these extra- 
 vasations form a prominent feature. (Plate xci.) 
 
 When the patient dies before the efflorescence is completed 
 the rash is likely to be still more anomalous than in the cases 
 already considered. The papules are soft, pale, and almost 
 flush with the surface of the skin. If hardly perceptible to 
 the eye, they are still less obvious to the touch. And what 
 makes the case still more puzzling is that the suppression of 
 the development of papules is apt to be more complete on the 
 face than elsewhere, because the face, being naturally best 
 supplied with blood, suffers most from the depression of the 
 circulation. Under these circumstances, when the observer 
 is confronted with an eruption, anomalous both in the 
 character of its lesions and in their apparent distribution, 
 it is not surprising that the nature of the case is easy to 
 mistake. Cases in which death wholly anticipates the 
 efflorescence are, in reality, very exceptional. More often, 
 when cases of that repute occur, it is possible to detect 
 a few papules if they are sought, not on the face, but 
 on some part of the body where the circulation is less 
 impaired. 
 
 The symptoms of haemorrhage. Even when these symp- 
 toms are pronounced, no patient runs up the whole gamut 
 of expression of the hsemorrhagic tendency. There are, 
 therefore, many possible combinations of the symptoms and 
 corresponding variety in the aspect of the case. Such dif- 
 ferences are determined by no sort of rule. Whether death 
 comes early or late, whether the focal rash is well or ill de- 
 veloped, the food or air-passages, the lungs, the kidneys, or 
 the cutaneous surface may be the seat of the dominating 
 hsemorrhagic symptom, or any combination may fall to be 
 endured. 
 
 It must not be assumed that the nature of the attack is 
 always advertised boldly in symbols of blood. Even if the 
 hsemorrhagic symptoms do ultimately become conspicuous,
 
 H^EMORRHAGIC OR TOXIC SMALLPOX 97 
 
 in most cases they are not of very early development. In the 
 action of the toxin on the blood-vessels, time seems to be an 
 element of importance ; and, as a rule, the haeinorrhagic 
 symptoms do not appear until late in the illness, and perhaps 
 not until near its close. 
 
 In a minority of cases the symptoms of haemorrhage never 
 become very prominent. Most of such cases are near the 
 borderland of the class. Yet these symptoms are not 
 necessarily pronounced when the attack is of the first severity. 
 New-born babies are especially susceptible to the operation of 
 the toxin, and occasionally die of toxic smallpox with the 
 hsemorrhagic symptoms wholly suppressed. 
 
 A child, 10 days after birth, developed a very scanty variolous rash, 
 the papules being very soft and inconspicuous even at the time of death, 
 which occurred four days later. Death was sudden. No haemorrhage 
 was observed during life, but at the autopsy a few trivial internal 
 extravasations were found. 
 
 Such cases suggest that, in excessive doses or in highly 
 susceptible subjects, the toxin may sometimes paralyse the 
 heart before it can injure the vessels. 
 
 Toxic rashes. Petechi* and such small cutaneous ex- 
 travasations are exceptional in often making their appearance 
 earlier in the illness than most other hsemorrhagic signs. 
 That circumstance is of service to the observer when the 
 petechiffl are components of a purpuric rash. 
 
 The purpuric rash. The purpuric rash, described in 
 Chapter X., is seen in a considerable proportion of toxic cases. 
 But it is sometimes so vivid and extensive, and the tendency 
 to blood-staining is so much exaggerated, that its identity is 
 apt to be obscured and its real nature to escape recognition. 
 In such cases the surface affected is packed densely with 
 small petechia? and pricked out with larger shot - like 
 extravasations ; while the erythematous matrix in which 
 these are embedded may appear as a broad sheet of dark-red 
 or violet discoloration. (Case VIIL, Chapter XI.) Sometimes 
 the change goes further, and the surface is splashed with 
 irregular patches of purple in which the finer markings are 
 H
 
 98 THE DIAGNOSIS OF SMALLPOX 
 
 lost. First seen thus, the best part of the skin of the trunk all 
 claret-stained, it may never suggest itself that the rash is 
 generically the same as the familiar stippled erythema limited 
 to the region about the groins. 
 
 There is another reason which, in toxic cases, is apt to 
 make this rash more difficult of recognition. It has been 
 mentioned that in some cases the erythematous basis of the 
 purpuric rash encroaches beyond its normal limits. (Chapter 
 X., p. 68.) This is most likely to happen when the patient 
 has toxic smallpox; the back and limbs may be then ex- 
 tensively invaded by the erythema, and even the whole body 
 covered. But whereas, ordinarily, such an overflowing of the 
 erythema is likely to be fugitive and not to obscure the 
 characteristic distribution of the rash, in toxic cases there is 
 the difficulty that any kind of erythema is liable to take on a 
 special character and to exhibit blood-stasis and some degree 
 of blood-staining. Nevertheless, even under such confusing 
 circumstances the identity of the rash is seldom lost, because 
 of the special aggregation of purpuric elements in its peculiar 
 area of choice. This exact identification of the purpuric rash 
 is of no little importance, because in some cases of toxic 
 smallpox the diagnosis turns upon its recognition. 
 
 Though in many instances the rash presents the striking 
 effects which have been described, it must be remembered 
 that even in toxic cases it more commonly displays the usual 
 characters of tint and distribution described in Chapter X. 
 
 It is risky to found a prognosis on the character of the 
 rash. Its association with extensive diffuse violet or purple 
 discoloration is generally portentous. Yet an unusually 
 vivid and deeply-stained rash is sometimes the occasion of a 
 mis-diagnosis of hsemorrhagic smallpox in the case of a 
 patient who makes a good recovery and, perhaps, never 
 develops more than an abortive focal eruption and a trifling 
 secondary fever. 
 
 Toxic erythema. In some cases of toxic smallpox another 
 kind of rash is encountered which, unlike the purpuric rash, 
 is devoid of any striking peculiarity of character or distribu- 
 tion. It occurs as a patchy or uniform erythema, sometimes
 
 H.EMORRHAGIC OR TOXIC SMALLPOX 99 
 
 limited to the trunk, sometimes extending to the limbs or 
 to the whole body. In many cases the erythema, like the 
 erythema of the purpuric rash, becomes the seat of diffuse 
 or blotchy blood-stains, especially when it persists until 
 near the fatal termination ; or, again, its uniformity may be 
 relieved by petechise. But the display of haemorrhage is an 
 accidental, not an essential attribute. In character, the rash 
 may resemble closely some of those benign toxsemic erythernata 
 Avhich are most prone to affect the trunk of the body. 
 (See Chapter X., p. 70.) The points of distinction are that 
 the toxic erythema is less fugitive, is of deeper tint, is liable 
 to exhibit blood-stasis or blood-staining, and is apt to produce 
 a leather-like stiffening or thickening of the skin which it. 
 occupies, so that the rash can be felt as well as seen. 
 But, in fact, the two kinds of rash are little likely to be 
 confused, because they are encountered in cases of so 
 different a character. 
 
 There is more risk of the toxic erythema being attributed 
 to another exanthem. The interrupted character which it 
 frequently displays may be the occasion of confusion with 
 measles, as is often the case with the rose rashes described in 
 Chapter X. The severity of the constitutional symptoms, 
 the insignificance of any symptoms of catarrh which may be 
 present, and the absence of pulmonary symptoms are a 
 combination which forms an important distinguishing 
 feature. Though oedema of the lungs is common with toxic 
 smallpox, this complication is not of early onset, and its 
 advent would be accompanied by other less ambiguous signs 
 The development of symptoms of haemorrhage, though not 
 absolutely precluding a diagnosis of measles, should suggest 
 an attitude of extreme caution. 
 
 A diagnosis of scarlet fever may be suggested either by 
 the toxic erythema or by the petechial rash. The mistake is 
 not very frequent, and there may be no facts to justify it 
 except the presence of the rash itself. Nevertheless the con- 
 dition of the throat may give colour to the mis-diagnosis. A 
 not infrequent symptom of toxic smallpox is a deep congestion 
 of the fauces, palate and root of the tongue, which gives place
 
 100 THE DIAGNOSIS OF SMALLPOX 
 
 quickly to a bloody extravasation into those tissues. (Chapter 
 XL, p. 79.) There is, however, no ulceration of the throat, 
 no exudation, no enlargement of the tonsils, no swelling of 
 the lymphatic glands or of the cellular tissue below the jaw. 
 Though the temperature may be high with toxic smallpox, 
 not infrequently it is low ; whereas with scarlet fever the fever 
 is high except with intensely malignant cases. And vomit- 
 ing, which is an extremely frequent and prominent symptom 
 of scarlet fever, is generally not very pronounced, and is often 
 absent even in the worst cases of smallpox. 
 
 Post-mortem signs. The results of the autopsy will 
 correspond with the signs of haemorrhage observed before 
 death ; extravasations of blood along the urinary tract will be 
 found when there has been haematuria, congested lungs when 
 there has been haemoptysis, gastric or intestinal extravasations 
 when there has been bleeding from the stomach or bowel. 
 Certain internal extravasations produce no symptoms, and in 
 their enumeration it will be presumed that only some ol 
 them will be detected in a particular case. 
 
 Lungs and air -passages. The structures along the respiratory tract 
 are liable to considerable damage. The pharynx, tonsils, palate, the 
 root of the tongue and the epiglottis may be stained black by the 
 effusion of blood. The larynx and trachea, also, are often deeply 
 stained. In many instances the lungs are deeply congested throughout ; 
 but sometimes the congestion is limited to their bases. In certain cases 
 distinct extravasations are found scattered about the lung tissue, and 
 sometimes wedge-shaped pulmonary "apoplexies" may be seen on the 
 surface. In most cases the tissue is not only congested but also 
 cedematous ; yet, as a rule, there is no pneumonic consolidation. 
 Pleuritic effusion is uncommon and always slight ; but recent pleural 
 adhesions are met with with some frequency. 
 
 Alimentary tract. The intestinal canal is much less frequently 
 affected. Violet petechise and larger purple extravasations may be 
 found scattered about the mucous membrane of the stomach and small 
 intestine. Occasionally the whole circumference of the gut for a few 
 inches is black from extensive extravasation beneath the mucous 
 membrane. 
 
 Urinary organs. Haematuria is associated with extravasations in 
 the kidney or, less frequently, in the bladder. In the bladder these 
 appear as black plaques upon the internal surface. In the kidney the 
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 H.EMORRHAGIC OR TOXIC SMALLPOX 101 
 
 extravasations are met with sometimes on the surface of the kidney 
 beneath the capsule. Less commonly the whole organ is enlarged and 
 congested. 
 
 Liver and spleen. The condition of the liver is singularly variable. 
 It is a remarkable fact that an illness of about a week in duration 
 should be capable of increasing so greatly the weight of the organ. In 
 the absence of any morbid change except those found after smallpox, 
 the weight attained may be anything up to 6 Ibs. But in most cases 
 the weight does not exceed 4 3 Ibs., and not infrequently it is within the 
 normal limits. In some cases the organ is much congested and, when 
 cut, drips with blood ; in other cases the tissue is pale. The liver 
 exhibits sometimes an early stage of " nutmeg " degeneration. In many 
 cases the tissue is unnaturally yellow in colour. This colour is probably 
 due, in most instances, to altered blood-pigment ; for, tbough fatty 
 degeneration is found occasionally, such a change is not very common. 
 Indeed, the tissue is so far from being soft, that in most cases an 
 unusual toughness is its main characteristic. 
 
 As often as not the spleen is within the normal limits of size ; 
 and when it is enlarged the weight seldom exceeds 12 ozs. The colour 
 and consistency are very variable. 
 
 Serou* is a ri', ices and connective tissue. The serous surfaces nearly 
 always exhibit a certain number of petechi;e and small circular extrava- 
 sations, but these are seldom very abundant. They occur in the 
 pleura, in the pericardium (chiefly in the visceral layer near the base of 
 the heart), and in the peritoneum. In the last situation the favourite 
 places are along the gut and in the mesentery. 
 
 Extravasations often occur in the areolar tissue in various situations. 
 Such effusions are most apt to come in the tissue about the kidneys and 
 along the attachment of the mesentery, and in those situations are not 
 infrequently rather extensive ; but smaller extravasations are liable to 
 be found almost anywhere, from the interrnuscular spaces to the fissures 
 of the brain. 
 
 \''i.<i-nlitr system. The condition of the blood should be noticed. 
 In the great vessels the blood is generally uncoagulated, and in some 
 cases it may be fluid even in the heart. More often, there is some 
 clotting in those cavities, more especially on the right side. The clot 
 may be red, and is often soft and friable ; but in some cases a firm 
 white clot is found. 
 
 Diagnosis. In this domain, so obscure and intricate and 
 so difficult of survey, it is impossible to show an easy path 
 among the pitfalls and the thickets. But there are a few 
 useful landmarks to be recognised. 
 
 Fortunately, in most cases it is not very difficult at least 
 to identify the disease. Most patients survive until the focal 
 rash has become a pronounced feature of the case ; and since
 
 102 THE DIAGNOSIS OF SMALLPOX 
 
 the outcrop of this rash commonly occurs at the usual time, 
 and the rash has the usual distribution, the correct diagnosis 
 will be suggested by that distribution, even though the lesions 
 be anomalous in character. Yet, since haemorrhage may be 
 a late or a terminal sign, the character of the illness may not 
 at first be easy of recognition, even when the disease itself can 
 be identified. It is, in fact, not an uncommon experience 
 that the gravity of the illness is not realised until near its 
 termination. An earlier recognition will depend, often, upon 
 the appreciation of symptoms less obvious than those of 
 haemorrhage ; the vivid tint of the rash, the softness of the 
 lesions, their tardy efflorescence and evolution, the deepening 
 collapse and the presence of some of those other signs which 
 were mentioned early in the last chapter. 
 
 The difficulties are most formidable in the minority of 
 cases when the rash is late in outcrop, unusually deliberate in 
 evolution, and atypical not only in character but also, at first 
 at all events, in distribution. The onset of haemorrhage and 
 its association with a papular or vesicular eruption will, in 
 many cases, ultimately suggest smallpox. But before haemor- 
 rhage occurs it may be easy to mistake the whole nature of 
 the disease. Indeed, in some cases the presence of the specific 
 lesions may be altogether overlooked. 
 
 In all these cases, and particularly in those in which the 
 outcrop is long delayed and perhaps anticipated by death, 
 a sign of inestimable value, if it is present and can be seized, 
 is the purpuric rash. It comes early in the illness, and its 
 frequency of occurrence increases with the severity of 
 attack It is, therefore, most frequent in the cases of which 
 the difficulties of diagnosis are most profound. It is often 
 stated that this rash is limited in its distribution to the groins 
 and hypogastrium, the so-called " genito- crural triangle." 
 Those who look always for such a limitation of the rash will 
 often miss it. But if it be remembered that it may have the 
 wider distribution which is often seen in these graver cases, 
 and if the vagaries of its character be allowed for, it will become 
 of twice the value. 
 
 Another sign which is, perhaps, still more common, and
 
 ELEMORRHAGIC OR TOXIC SMALLPOX 103 
 
 for which the observer should not fail to seek, is enlarge- 
 ment of the liver. This, when present, is easy of detection. 
 When the enlargement is considerable, the edge of the liver 
 may be found as near the umbilicus as the ribs. But the 
 value of the sign is less conspicuous than that of the sign 
 last discussed. The symptom does not appeal to the eye, 
 and is therefore the easier to miss. It becomes prominent 
 later in the case. It is not pathognomonic of smallpox and, 
 unless the growth be watched, it cannot confidently be ascribed 
 to the current illness. Nevertheless, the symptom may afford 
 very valuable confirmatory evidence in a case of doubt, 
 especially in the cases of children and young adults. 
 
 When the purpuric rash is absent and death takes place 
 before the outcrop, the diagnosis must rest heavily upon the 
 hiemorrhagic symptoms. In these cases, happily not numer- 
 ous, such diseases suggest themselves, according to the char- 
 acter of the haemorrhage, as diphtheria, acute nephritis, 
 blood-poisoning. Diphtheria, like scarlet fever, is apt to be 
 suspected when there is extravasation into the mucous mem- 
 brane of the fauces, and diphtheria is well known to be 
 associated sometimes with hsemorrhagic symptoms. But with 
 toxic smallpox there is never any formation of membrane. 
 " Blood-poisoning " is the commonest mis-diagnosis in these 
 obscure cases, and many an outbreak of smallpox has been 
 traced back to a case so labelled. So inexact a diagnosis 
 may be regarded as little more than a confession of ignor- 
 ance of the nature of the illness, the fact being that 
 smallpox was never thought of. Occasionally a case of 
 enteric fever, of ulcerative endocarditis, or of some other dis- 
 ease is certified as toxic smallpox on the strength only of 
 certain signs of haemorrhage. In such instances a know- 
 ledge, not so much of the hsemorrhagic, as of the associated 
 symptoms of toxic smallpox, would go far to shake the 
 erroneous conclusion.
 
 CHAPTER XIY 
 ERYTHEMATA : SIMPLE AND SYMPTOMATIC 
 
 Measles. More than a thousand years ago the difference 
 between smallpox and measles was recognised by Rhazes, the 
 Persian. Smallpox, he said, is ushered in by pain in the back, 
 and its papules are round and ,prominent ; whereas the 
 papules of measles are nearly level with the surface of the 
 skin. With the latter disease, doubtless, he grouped scarlet 
 fever and other acute fevers distinguished by an extensive 
 symmetrical erythematous eruption ; and since in his writings 
 he constantly coupled the two names, it may be questioned 
 whether he looked upon smallpox and measles as more than 
 different forms of the same malady. However that may be, 
 no adequate distinction was made in later ages, and it was 
 not until the time of Sydenham that smallpox, measles and 
 scarlet fever were clearly recognised as separate diseases 
 breeding true. 
 
 Confusion between things so distinct is less surprising 
 when it is remembered how vague was the pathology of those 
 times. A disease was the expression of a morbid tendency, 
 or state of the blood, which showed itself in this way or in 
 that according to the idiosyncrasy of the individual, his 
 mode of life, or so forth. In the days when infectious 
 disease ran riot, and a pestilence was supposed to be as much 
 in the order of nature as an earthquake or a flood, accurate 
 observations as to the generation of these fevers were not easy 
 to make. Smallpox, like measles and scarlet fever, was then 
 a disease of childhood. And if he began with the assumption 
 that it depended upon the patient's complexion, or upon the 
 state of the weather, for an erythematous or papular eruption 
 to give place, or not to give place, to vesicles and pustules, a 
 man might live a lifetime and not find out the difference. 
 
 104
 
 105 
 
 He might, like Rhazes, detect a difference between the soft 
 flat rash of measles and the raised papules of smallpox ; yet 
 when he observed other cases in which a toxsemic rash, to all 
 appearance like the rash of measles or of scarlet fever, was 
 followed by a pustular eruption, how could he but conclude 
 that the difference was unessential ? Even the distinction 
 which Rhazes drew does not always liQld good. There is 
 many a rash of measles and many a papular variolous rash 
 which few of us could tell apart. It is such rashes which 
 now fall to be considered. 
 
 When measles is mistaken for smallpox, the patient, very 
 generally, is an adult. Measles in adult life is not very 
 uncommon, and the illness is not insignificant. That many 
 more adults do not suffer is due only to the fact that most 
 have acquired immunity by a previous attack. 
 
 The symptoms of invasion of the two diseases are very 
 similar. With each an interval of a few days elapses be- 
 tween the onset of illness and the outcrop of the rash. In 
 selected cases, no doubt, the constitutional symptoms of one 
 disease and the other may show considerable divergence ; but 
 even pain in the back is not wholly characteristic, and there 
 is hardly a combination of symptoms possible to one disease 
 which may not be found occasionally with the other. Catarrhal 
 symptoms are the most distinctive feature of measles, and if 
 these should be very pronounced they would afford good 
 evidence in its favour. Yet, otherwise, such symptoms 
 would not be of the first value ; for with smallpox the eyes 
 are suffused and there may be lacrymation (Plate xciv.), some- 
 times the conjunctiva is slightly injected, and there may be 
 even a complaint of sore throat. The presence of Koplik's 
 sign would be of importance, but not its absence ; for by the 
 time the rash has become evident the sign may have dis- 
 appeared. It should be remembered that the lesions of 
 smallpox are very early to develop on the mucous membrane 
 of the mouth, and may be found sometimes in that situation 
 before the papules have appeared on the skin. Upon the 
 mucous membrane the lesion comes as a small red soft spot 
 which soon becomes grey. There might be some risk of con-
 
 106 THE DIAGNOSIS OF SMALLPOX 
 
 fusing Koplik's spots with these variolous lesions but for the 
 fact that the latter have a different distribution, being found 
 chiefly on the palate and fauces and but to a slight extent, if 
 at all, at the side of the mouth. 
 
 A more telling point of difference may lie, not so much 
 in the character, as in the intensity of the symptoms of 
 onset. For a patient with measles to present a profuse 
 eruption, he need not be very ill nor have an attack of 
 more than average severity. (Plate xcii.) But for a similar 
 rash to be caused by smallpox, the patient must have a 
 confluent papular eruption and an exceptionally severe ill- 
 ness. If measles be really the disease, this disparity between 
 the character of the symptoms and the character of the rash 
 may furnish significant evidence against the other. Patients 
 with confluent papular smallpox, or those who have an 
 exceptionally severe toxaemic fever, are, in fact, just those 
 who are apt to exhibit an eruption of which the elements 
 approach closely in character to those of measles. The pros- 
 tration attending the illness so alters the character of the 
 rash that the papules fail to convey that sense of definition 
 and resistance on which the recognition of them so much 
 depends. (Chapter VI., p. 40.) The papule, in such a case, be- 
 comes something like the papule of measles, which is soft, lacks 
 prominence, and merges imperceptibly into the areola which 
 surrounds it. (Plate xcm.) The similarity is most noticeable 
 on the exposed parts, the face, hands and wrists. On the 
 face the rash of measles may pass itself off very well for a 
 confluent papular variolous rash of such close texture that 
 the individual elements are indistinguishable. About the 
 wrists the rash is less likely to be confluent, but in that 
 situation the papules are apt to be exceptionally prominent 
 and well defined, and not far removed in character from 
 the papules of smallpox. Under such circumstances a hasty 
 inspection of the case is very likely to convey a wrong 
 impression ; but an examination of other parts of the skin 
 generally reveals elements of too discordant a character and 
 of too indifferent a distribution to be consistent with such a 
 diagnosis.
 
 SYMPTOMATIC ERYTHEMATA 107 
 
 The real trouble comes earlier, when the rash is only 
 partly developed. On p. 33 it was pointed out that a papular 
 variolous eruption, sufficiently early in efflorescence, has an 
 incomplete distribution and is limited to the face and upper 
 part of the body. That circumstance must be remembered 
 in differentiating any papular eruption of similar arrange- 
 ment. The fact is of particular importance in the case of 
 measles, whose rash, like that of smallpox, begins at the 
 top and spreads downwards. In such a stage of events the 
 character of the lesions of the two diseases may be indis- 
 tinguishable ; for variolous papules of only a few hours' 
 growth may be quite as soft and inconspicuous as those of 
 measles of a similar age. Though the identity of arrange- 
 ment may be almost as complete, the distribution may 
 nevertheless be the most reliable guide. The rash of measles 
 is wont to explore the parts round the ears, on the fore- 
 head, and among the hair-roots, and to display indifference 
 to the flexures of the body and to the bays and promontories 
 of the cutaneous surface. (Plates XXXIIL, Fig. 2, xciv., and 
 xcv.) Fortunately the resemblance is fleeting, and a few 
 hours will change the whole aspect of the rash. 
 
 There seems to be no tendency to confuse the papular 
 variolous eruption with measles, the mistake being almost 
 always in the other direction. Yet a very large number 
 of cases of smallpox are at first mistaken for measles, for 
 with the majority of patients who exhibit a toxaemic rose 
 rash measles is the preliminary diagnosis. The points of 
 distinction were enumerated in Chapter X (p. 71.). The mis- 
 conception would nearly always be avoided if it were re- 
 membered that an erythernatous eruption is probably not 
 due to measles unless it is associated with distinct symp- 
 toms of catarrh. It cannot be said that the mistake is an 
 important one, as it tends to be so speedily corrected. The 
 error is more serious, though less frequent, when the patient 
 has toxic smallpox with a diffuse erythematous toxic rash. 
 The death may then be certified to be from measles, the real 
 fact being disclosed only by the lamentable occurrence of 
 secondary cases. To the remarks made in the last chapter
 
 108 THE DIAGNOSIS OF SMALLPOX 
 
 (p. 99), it may be added that measles with haemorrhage 
 is very rarely encountered except with young or weakly 
 children. 
 
 Other infectious exanthems. Scarlet fever Rubella 
 The toxsemic rashes of smallpox, which so often suggest 
 measles, occasionally suggest scarlet fever, but the latter 
 misapprehension is incomparably the less frequent (pp. 69 and 
 72). A similar mis-diagnosis may be caused by the rashes 
 of toxic smallpox (p. 99). 
 
 Unlike that of measles, the eruption of scarlet fever 
 cannot very well be confused with the papular variolous rash. 
 But the scarlatinal rash is capable of being mistaken for a 
 toxsemic eruption, though such an accident should be 
 prevented by an examination of the tongue and throat and 
 glands. Rubella, also, may occasion a similar mistake. 
 Such a misunderstanding in the case of either disease is 
 exceptional, and comes about by the association of one of 
 them with an outbreak of smallpox. Smallpox never causes 
 enlargement of the glands early in the illness, and the 
 condition of the tongue produced by it has none of the 
 scarlatinal characteristics. 
 
 Enteric fever. Enteric spots have been mistaken for 
 variolous papules when the disease has been latent, and the 
 rash unusually plentiful. The enteric rash is somewhat more 
 deceptive when some of the lesions, as may be the case, show 
 a tendency to become vesicular. An immature papular 
 variolous eruption, on the other hand, has sometimes led to a 
 diagnosis of enteric fever. Both accidents are exceptional. 
 Rose spots are softer and less prominent than the papules of 
 smallpox, and are differently arranged. Their choice is for 
 the trunk, and for the chest and abdomen rather than the 
 back. It is not uncommon for the spots to be found upon 
 the thighs ; but the arms and legs, and above all the face, have 
 little liability to be affected. 
 
 With some cases of enteric fever it is well known that, 
 besides or instead of the usual exanthem, purpuric spots are 
 developed in the skin. These may be like flea-bites, or may 
 be larger and rather darker in tint. In such cases the attack
 
 SYMPTOMATIC ERYTHEMATA 109 
 
 is not necessarily of more than average severity. These 
 hsemorrhagic extravasations occasionally suggest a diagnosis 
 of toxic smallpox. Against that view would be the absence 
 of severe pain, of severe constitutional disturbance, and of 
 serious prostration ; the facies would be different from that 
 of toxic smallpox ; an enlarged spleen would not count for 
 much, but there would be no enlargement of the liver ; and, 
 almost certainly, there would be no other hsernorrhagic 
 symptom, and no erythematous rash. 
 
 Typhus. If this were a commoner disease, or if an out- 
 break of it were associated with an epidemic of smallpox, the 
 two things might be more often confused. Occasionally toxic 
 smallpox is certified as typhus, but this result arises from 
 deficient experience and not from a real resemblance between 
 typhus and toxic smallpox ; the patient has fever and exhibits 
 ha'morrhagic extravasations into the skin, and typhus is 
 known to be a disease with which this association is constant. 
 The fact is, when typhus, as often happens, fails to be 
 recognised, toxic smallpox has no tendency to suggest itself 
 as a possible diagnosis. On its first appearance the rash of 
 typhus does not suggest haemorrhage. It is an erythema, like 
 the rash of measles ; the papules are pink or red, and though 
 the colour may from the first be difficult to discharge by 
 pressure, it is not until later that the spots become distinctly 
 hsemorrhagic. The temptation with typhus is to mistake the 
 rash for that of one of the commoner exanthems scarlet 
 fever, or enteric fever, or measles ; and in the rare cases in 
 which smallpox is suspected, it is the papules of discrete or 
 confluent smallpox for which the lesions are mistaken. For 
 the misconception to arise, the papules, like those of measles 
 under similar circumstances, must be unduly firm and 
 prominent. But the distinction is very much easier than 
 with measles, because the distribution of the eruption of 
 typhus does not resemble that of a variolous rash at any time 
 of its development; it does not begin on the face, and in 
 many cases never appears there ; on the contrary, it is apt to 
 appear early and to be pronounced upon the abdomen anfl 
 neighbouring parts.
 
 110 THE DIAGNOSIS OF SMALLPOX 
 
 Simple or unspecific erythemata. Simple purpura. 
 If the purpura of typhus can be suggestive of smallpox, it 
 is not surprising that the mistake should be more frequent 
 with simple purpura, a disorder so much more frequently 
 encountered. In such cases the lesions appear first as pink, 
 slightly elevated, erythematous macules, and it is when they 
 are in that state that they are deceptive. The illness is some- 
 times attended by slight fever and by some pain in the limbs, 
 a circumstance which adds force to the suggestion of an exan- 
 them. The resemblance does not persist, because the colour 
 of the spots rapidly deepens and becomes fixed, even if it is 
 not imperfectly mobile from the first. The spots, although 
 they may be unduly prominent and form definite papules, 
 lack altogether the peculiar firmness of variolous papules. 
 
 Erythema rheumaticum. This malady, like simple pur- 
 pura, resembles smallpox only in exceptional cases, the lesions 
 being generally of too divergent a character to be mistaken. 
 Yet the confusion arises less infrequently with this disorder 
 than with the other, for the reason that the papules are more 
 apt to be firm and prominent and occasionally display a 
 tendency to become vesicular. Some of the lesions may be 
 very like variolous lesions of the age of a day or two, and the 
 resemblance is furthered by the association of the eruption 
 with febrile disturbance and pain in the joints. Nevertheless, 
 even if there are no definite rheumatic symptoms and no 
 grossly discordant lesions, it is seldom that the patient does 
 not exhibit among the rest some lesions which are plainly 
 purpuric or urticarial. (Plate xcvu., Fig. 1.) 
 
 Erythema nummulare Erythema bullosum. In ex- 
 ceptional instances of mistaken diagnosis there are to be 
 found lesions characteristic of erythema bullosum round 
 erythematous patches, as large as a shilling or larger, sur- 
 mounted by a large vesicle. The vesicle may be full and 
 tense, or flat and empty, and is encircled by a red zone. If 
 the vesicle be flat, the pellicle may be of a pearl-grey colour 
 throughout, or may be discoloured at the centre by partial 
 incrustation or by pigmentation of the skin below. When 
 such examples of the malady are confused with smallpox, the
 
 SIMPLE ERYTHEMATA 111 
 
 confusion arises in spite of, and not because of, the presence of 
 the characteristic lesions, for these are associated with other 
 lesions having but a feeble resemblance to the prototype. 
 These less typical lesions are more plentiful. They are 
 circular erythernatous discs of smaller size, some or most of 
 which display a small central vesicle. It is more common to 
 see cases in which the characteristic bullous lesions are absent, 
 the eruption being composed entirely of elements of the 
 character last described. In other cases the vesicles are 
 altogether wanting, and the patient presents a crop of erythe- 
 matous discs slightly raised, like pink wafers stuck upon the 
 skin. (Plate xcvi.) The cases considered in this paragraph, 
 in fact, form a series, at the head of which stand those to 
 which the terms erythema bullosum or erythema iris may be 
 more aptly applied. The lesions of no member of the series 
 have any real resemblance to those of smallpox, being too 
 soft and superficial. 
 
 All the foregoing varieties of erythema differ from the 
 variolous eruption in the circumstance that their favourite 
 situations are the limbs, especially the extensor surfaces, 
 while the trunk and, above all, the face show but little 
 liability to be affected. Thus erythema bullosum and the 
 allied eruptions affect the extensor surfaces of the forearms, 
 the legs suffer less often, and the rash seldom extends to the 
 trunk. Erythema rheumaticum is generally confined to the 
 legs; and though the rash may come on the arms and 
 trunk, lesions occur upon the face only exceptionally. The 
 face is the seat of a simple purpura more frequently, but 
 even with that eruption the limbs are the more favourite 
 choice. 
 
 Erythema multiforme Acute urticaria. The generic 
 term, erythema multiforme, is restricted here to some varieties 
 of erythema which differ in certain particulars from those 
 hitherto mentioned. The eruption, as a rule, is more profuse ; 
 it is more catholic in its choice of situation ; and from case to 
 case, and even in the same case, there is more diversity in the 
 character of the elements. It is not necessary to insist on 
 these differences; the classification of the erythemata, to a
 
 112 THE DIAGNOSIS OF SMALLPOX 
 
 great extent, is arbitrary. But since the circumstance tends 
 to influence the judgment at the bedside, it is well to recog- 
 nise that different cases of simple erythema of all kinds, and 
 of erythema multiforme in particular, may have a widely 
 different clinical aspect. 
 
 Among the cases which are liable to be mistaken for 
 smallpox there is. naturally, not the same scope for variety of 
 lesion. The bulk of the eruption is composed of papules or 
 macules comparable in poin\ of size with the lesions of 
 smallpox or of measles. When the rash consists wholly of 
 papules which are distinct and prominent, an event which is 
 more likely to occur when the rash is not very profuse, the 
 disorder may be called erythema papulatum. ' (Plates xcvin., 
 Fig. 2, and xcix.) More often, the eruption consists in one place 
 of firm and prominent papules, in another of soft flat lesions 
 which, if they are near together, blend with one another as 
 do the papules of measles. (Plates xxxn. and xxxm., Fig. 1.) 
 In other cases, again, all or most of the lesions are of the latter 
 character. Sometimes the papules lie in a diffuse erythe- 
 matous matrix, with which in places, losing their individuality, 
 they may become completely merged. (Plate ci., Fig. 1.) 
 Another difference from smallpox may not infrequently be 
 found in the presence of a few very large papules or tubercles 
 which would obviously be foreign to a papular variolous 
 eruption. 
 
 A trait which is particularly apt to engender suspicion is 
 the tendency, which often exists, for some of the lesions to 
 take on an appearance as of impending vesiculation. The 
 formation of definite vesicles with serous contents is less com- 
 mon, and, when it occurs, is generally slight in extent. 
 In very exceptional cases, however, that feature is con- 
 spicuous and is displayed by a large number of the lesions, 
 so that parts of the surface may be occupied by a vesicular 
 eruption, to the . exclusion of the papular elements. (Plates 
 xcvn.,Fig. 2, and XCVIIL, Fig, 1.) The vesicles are superficial. 
 In other cases some of the lesions become urticarial, and the 
 eruption may be described as a compound of urticarial and 
 erythematous papules. Or the rash may be wholly, or almost
 
 SIMPLE ERYTHEMATA 113 
 
 wholly, of an urticarial character and may be called an acute 
 urticaria. (Plates ci., Fig. 2, en. and cm.) 
 
 Aberrations from the variolous type of lesion, though 
 evident when sought for, may not be very conspicuous on the 
 surface ; and at first sight some of these eruptions, associated 
 as they are apt to be with febrile symptoms, may be exceed- 
 ingly suggestive. The aspect of the case varies with the 
 profuseness of the rash, which may suggest a trivial or a 
 serious attack. As with other forms of erythema, the inci- 
 dence of the rash may be chiefly on the limbs; but it is 
 frequently much more widely diffused. (Plates c. and xxxi.) 
 And not only may the rash be abundant upon the face but 
 the lesions may appear even upon the palate. The order of 
 incidence, however, is seldom the same as with smallpox, and 
 as a rule the diffusion of the eruption is incomplete. All 
 varieties of the disorder run a similar course and the patient 
 is quit of his symptoms after a few days. During involution 
 the rash loses all its mimetic qualities. 
 
 Acute febrile erythema. Experience teaches that the 
 various kinds of simple erythema are closely related, and sug- 
 gests that the difference of anatomical character among these 
 rashes is due as much to personal idiosyncrasy as to differ- 
 ence of ultimate cause. The several varieties which may be 
 separated are to be regarded as types only, and are linked 
 together by many intermediate forms. It is, therefore, not 
 to be inferred that the cases grouped under the title of acute 
 febrile erythema are capable of distinct separation, pathologi- 
 cally or clinically. They are merely extreme examples of 
 erythema multitbrme, and are separated only because it is a 
 common custom completely to misinterpret their character. 
 
 The pathology of the whole group of simple erythemata 
 is very imperfectly understood. That most cases are 
 rheumatic, there is no evidence to show; even with those 
 which would be generally classed as examples of erythema 
 rheumaticuin the evidence of rheumatism is often incomplete. 
 Excepting those instances in which the erythema is secondary 
 to an infection or to the ingestion of a poisonous drug or a 
 poisonous food, we are hi ignorance of the cause of most of 
 i
 
 114 THE DIAGNOSIS OF . SMALLPOX 
 
 these eruptions and can conclude only that they are toxsemic. 
 That the rash is an expression of a toxemia is in harmony 
 with the fact that it is commonly associated with and often 
 preceded by febrile symptoms, symptoms which are peculiarly 
 distinct in the cases now to be discussed. 
 
 While it would not be accurate to say that with, cases of 
 erythema multiforme the severity of the constitutional symp- 
 toms is in proportion to the abundance of the eruption, it is 
 a fact that when those symptoms are unusually prominent 
 the eruption is generally profuse. Cases occur, by no means 
 infrequently, in which the patient displays an eruption cover- 
 ing the whole or the major part of the cutaneous surface, and 
 exhibits febrile symptoms which are so pronounced as to be 
 most suggestive of the onset of an acute specific fever. The 
 onset of illness is distinct and may be sudden, and frequently 
 precedes, perhaps by as much as two or three days, the out- 
 crop of the rash. The fever may be considerable, and the 
 temperature may reach 103, 104, or even 105. The 
 patient feels ill and usually suffers from headache, which is 
 sometimes severe, and from pain in the limbs. With some 
 cases there is nausea or vomiting ; these symptoms are 
 occasionally very prominent, and may be associated with 
 diarrhoea. The tongue is furred, and the patient may complain 
 of sore throat, examination revealing injection of the soft 
 palate and fauces ; but sore throat is a symptom only in a 
 minority of the cases. In exceptional instances the illness is 
 alarming. The fever runs high and there may be delirium. 
 The patient is prostrate, has a dry tremulous tongue, and 
 appears to be in danger of succumbing. Yet, in the author's 
 experience, such symptoms are illusory, and all cases end 
 alike. Within a week the symptoms abate, the rash begins 
 to fade, and recovery is uninterrupted and rapid. The follow- 
 ing is an example of a case of moderate severity. 
 
 N. D., aged 20, a gasfitter's labourer, previously in good health, 
 developed the rash on the third day of his illness. During the first two 
 days he had to give up his work, stay at home and lie down. He had 
 pains in the legs, arms, and shoulders, and suffered from frontal head- 
 ache. He was sleepless and lost his appetite. On the third and fourth
 
 SIMPLE ERYTHEMATA 115 
 
 days of the attack he complained of sore throat. He came under 
 observation on the fourth day. He was flushed and perspiring. The 
 lips were full and dry and rather tremulous. The tongue was moist 
 and covered with a white fur. There was slight faucial injection. The 
 temperature was 103. 
 
 There was a discontinuous erythematous rash. This was most 
 abundant on the limbs, especially at the distal ends. It was very thick 
 on the backs of the hands, wrists, and feet. Higher up the limbs, the 
 spots thinned out. The rash was present on the face, but not so 
 abundantly as on the limbs. It was least abundant on the trunk, but 
 was as pronounced in front as behind. There were a few spots on the 
 hard palate. 
 
 The rash was dark red. For the most part it was made up of small 
 round spots, many about a quarter-inch across, many smaller. Most of 
 these spots were slightly raised. All were soft The resemblance to 
 the papules of measles in some instances was very close. But some of 
 the papules looked as if about to become vesicular, and in a few places 
 there were small vesicles with serous contents lying on a raised erythe- 
 matous base. In other places the elements of the rash were lost in a 
 patch of diffuse erythema. The hands and feet were slightly osdema- 
 tous. On the fifth day of illness the rash began to fade and the symp- 
 toms abated. The patient made a speedy recovery. 
 
 Except that they are superabundant, these eruptions do 
 not differ in their characteristics from those of other forms of 
 erythema inultiforme, and they are as easily separable from a 
 papular variolous rash. In many cases the eruption is extra- 
 ordinarily profuse and covers the whole body. Examples of 
 such rashes figure in the plates, (civ., cv., cvi., and cvn.) 
 Profound constitutional disturbance and an abundant eruption 
 covering face and trunk as well as limbs are a combination 
 which is especially deceptive; but such universal eruptions 
 can, at the worst, be as easily separated by their distribution 
 as a profuse eruption of measles. 
 
 It is for measles, indeed, that acute febrile erythema is 
 most frequently mistaken, and the plates will show how close 
 may be the resemblance. Most patients, suffering from acute 
 febrile erythema, who have come under the author's observa- 
 tion have been young adults, but such patients have been 
 certified for smallpox, and most patients with measles who 
 earn certificates of smallpox are young adults also. There is 
 no reason to suppose that acute febrile erythema has a
 
 116 THE DIAGNOSIS OF SMALLPOX 
 
 different age-incidence from other forms of simple erythema, 
 and therefore that there is a distinct difference from measles 
 upon that score. The following may be regarded as the chief 
 clinical distinctions between the two maladies. The interval 
 between the' onset of illness and the outcrop of the rash is 
 usually shorter with acute febrile erythema, and may be 
 altogether wanting. The efflorescence of the rash generally 
 proceeds differently with the two diseases ; the eruption of 
 measles begins on the face and spreads downwards, but with 
 the simple erythema there is no such constant proclivity. In 
 many cases, too, the order of incidence is different, the limbs, 
 with the simple erythema, often suffering more than the face 
 and trunk ; in some cases of acute febrile erythema, however, 
 the rash is so profuse that no such difference is apparent. 
 With measles it is but rarely that there is a tendency to 
 the development of vesicles or pseudo-vesicles, whereas that 
 tendency is a common feature of the other eruption. Again, 
 the rash of measles is regular and uniform, but the simple 
 erythema' is often irregular and multiform. A most important 
 and essential characteristic is the prominence of catarrhal 
 symptoms with measles. Though with the other disorder 
 there may be sore throat, pronounced catarrhal symptoms 
 are almost always wanting. Lesions which could be mistaken 
 for Koplik's spots are not found in the mouth with simple 
 erythema, but it should be remembered that erythematous 
 spots may be found upon the palate. 
 
 The differential diagnosis from measles has been dis- 
 cussed because it must often have appeared to the observer 
 that the choice in diagnosis lay between smallpox and 
 measles, instead of between smallpox and a third disease. 
 A widely diffused erythema, accompanied by febrile symptoms, 
 is not necessarily symptomatic of an acute specific fever.
 
 PLATE XCII. 
 
 These two figures are from the same patient, and show the universal and indis- 
 criminate distribution of the mature eruption of measles. From the crown 
 of the head downwards, the rash overflowed, surely and evenly, the whole 
 cutaneous surface.
 
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 u 
 
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 c
 
 It 
 
 
 PLATE XCIV. 
 
 The patient had smallpox, but the disease was mistaken for measles. The 
 resemblance was enhanced by the presence of distinct catarrhal 
 symptoms ; that the eyes were suffused and tearful may be judged 
 from the print. Though efflorescence was incomplete, the distribution 
 more nearly resembled that of smallpox. The incidence was greater 
 than usual on the lower half of the face, and the rash was abundant 
 below the jaw, but those events occur sometimes with young children. 
 On the other hand, the eruption was deficient in the orbit, although, 
 because the eyes were open, that fact is not very apparent in the print 
 (compare with Plate xxxill., Fig. 2). The distribution on the neck, 
 bust and arms should be compared with that pictured in the next 
 plate, which supplies a forcible contrast to this figure.
 
 PLATE XCV. 
 
 From a case of measles. The rash covered the face and filled the orbits. It was strewn 
 equally over the neck, shoulders, and chest. It came indifferently on the ridges and 
 in the hollows, filling the supraclavicular space, the suprasternal hollow, and the 
 intermammary groove.
 
 PLATK XCVI. 
 
 In each figure there is portrayed an eruption of erythematons wafer-like discs on the back 
 of the hand and wrist. The surface of the discs was slightly elevated above the level 
 of the skin. In the first case, at the centre of almost every disc a small vesicle could 
 be discerned. In the second case, with few exceptions, these vesicles were absent. 
 The spots in this case were notably smaller than in the first, and therefore more 
 mimetic.
 
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 PLATE C. 
 
 Erythema papulatum of extensive distribution. The rash covered the trunk, limbs, and face. 
 Tliere were apparent many differences from the distribution of smallpox, but these 
 were displayed chiefly in points of detail.
 
 PLATE CI- 
 
 Fig. 1. Erythema multiforme. The rash was confluent on the hands, and 
 simulated closely a profuse papular variolous eruption. But in places, as 
 the print shows, the individuality of the papules was wholly lost. The 
 general distribution of the rash was very nnlike that of smallpox. 
 
 Fig. 2. Acute urticaria. This print and the next (Plate en.) are from the 
 same patient. The rash was generalised, but, in distribution, showed 
 wide departures from the variolous pattern. The face was not much 
 affected, the incidence being greater on the limbs. The rash was 
 thicker on the back than on the front of the trunk, but its disposition 
 was somewhat patchy. The flexor surfaces of the limbs suffered 
 equally with the extensor, and the rash invaded the armpits.
 
 
 PLATE CI.
 
 59 
 
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 s2
 
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 PLATK CVI1. 
 
 Acute febrile erythema in the case of a child. The rash was confluent on the 
 face, and" elsewhere its elements were coherent. The resemblance to 
 smallpox was closer at an earlier stage of the illness. In the state depicted 
 the affinity was rather to measles, from which the case was distinguished 
 by the absence of symptoms of catarrh, by the irregular and splash-like 
 character of the rash, and by the large size of its elements.
 
 CHAPTER XV 
 
 CHICKENPOX 
 
 CHICKEXPOX is mistaken for smallpox about half as frequently 
 as all other diseases combined. In the majority of cases the 
 resemblance is superficial only ; but there are some in which 
 the lesions approximate in character so closely to those met 
 with in many cases of the graver disease that the distinction 
 would be very difficult, did it turn only upon the symptoms 
 and upon the character of the spots. Fortunately the 
 eruption of each disease has so much individuality of dis- 
 tribution that it is only when the rash is scanty, and when 
 there is a dearth of evidence of any kind, that the judgment 
 need be seriously in doubt. 
 
 Chickenpox is a disease of childhood, and smallpox, at the 
 present day, a disease of adults. That to this rule there 
 are many exceptions is, perhaps, not fully realised, for many 
 adult patients are wrongly certified. Chickenpox is not 
 uncommon among adults, and occurs up to middle age ; and 
 adults get by no means sparse eruptions. (Plates xxix., ex., 
 and cxi.) The disease is as easy of recognition in their 
 cases as in the cases of children ; but not infrequently the 
 decision has rested, it would appear, not upon the evidence, 
 which was unambiguous, but just upon the mathematical 
 probability. Contrariwise, smallpox is sometimes mistaken 
 for chickenpox, not so much from the inherent difficulty of 
 the case, as because the patient happens to be a child, and 
 chickenpox a disease of childhood. 
 
 The method of onset of the illness is as insecure a guide 
 as the age of the patient. The eruption of smallpox is 
 usually preceded by a period of fever, and the fever of 
 chickenpox is generally coincident with the outcrop of the 
 rash. Not infrequently, however, the eruption of chicken- 
 in
 
 118 THE DIAGNOSIS OF SMALLPOX 
 
 pox is preceded by fever and malaise ; indeed, in rare cases 
 there is, as is so often the case with smallpox, a prodromal 
 or a coincident erythema.* 
 
 On the other hand, in cases of smallpox of the milder 
 sort the outcrop of the rash may be the first symptom to 
 be displayed. The presence or absence of precedent febrile 
 symptoms is, in fact, not of much account in the class of 
 cases which fall to be distinguished. Nor is there much 
 significance in the amount of fever which accompanies or 
 succeeds the efflorescence. 
 
 The eruption. Much weight should not be attached to 
 the mere density of the eruption. Though confluent chicken- 
 pox is highly exceptional, the rash, not infrequently, is de- 
 veloped in surprising quantity, and vesicles, here and there, 
 may be coherent. 
 
 In most cases the lesions of chickenpox seem to begin 
 as vesicles ; yet, probably, such is not really the case. If 
 the rash be seen early enough, there may generally be 
 observed among the vesicles some small papules, soft, hardly 
 raised above the surface for the most part mere flecks. 
 These papules are so evanescent that the vesicles seem to 
 start, ready made, from the skin. Yet in some cases 
 the papules are larger, better formed, and longer lived. 
 The rash then may be said to pass through a distinct 
 papular stage; and if the patient be seen on the day of 
 outcrop he may exhibit a rash wholly papular, and 
 have an exceptional opportunity of earning a certificate of 
 smallpox. 
 
 Character of the lesions. The differential diagnosis of 
 the two diseases must almost always be determined by the 
 evidence presented by the eruption, and the trend of cus- 
 tom, perhaps, is to give undue weight to the character of 
 the lesions, or rather to certain traits of character. This 
 body of evidence, certainly, is of the greatest moment, but 
 it is necessary to keep the component features in perspec- 
 tive. Just as with smallpox the salient feature is that the 
 
 * For an account of the accidental rashes of chickenpox, see J. D..Rolleston, 
 British Medical Journal, May 4th, 1907.
 
 CHICKENPOX 119 
 
 focus of the lesion lies deep among the epidermal cells, so 
 with chickenpox it is that the focus lies immediately be- 
 neath the cuticle. And by as much as either disease de- 
 parts from that rule, by so much do its lesions approximate 
 in character to those of the other. 
 
 That the lesions of chickenpox are rooted near the sur- 
 face can generally be made out best by inspection and 
 manipulation. The exceedingly superficial and fragile-look- 
 ing vesicles which doubtless suggested such names as glass- 
 pox and Windpocken, though common enough in practice, are 
 not often seen in cases which are likely to be misinterpreted. 
 Yet, even though the vesicles be somewhat more deeply 
 placed, the distinction in position between the lesions of the 
 two diseases is generally very easy to appreciate. (Plate 
 cvni.) Even when the spots have dried up the difference 
 can generally be perceived between the scabs of chickenpox 
 adhering to the surface and the counter-sunk scabs of small- 
 pox. 
 
 Interpreted, not as a specific sign, but merely as additional 
 evidence of the position of the lesion, there is no objection to 
 regarding the absence of loculation in the vesicle as a feature 
 of the disease. But it must be remembered that a few 
 multilocular vesicles are met with sometimes in cases of 
 chickenpox, and that unilocular vesicles are not an uncommon 
 feature of smallpox. 
 
 An interesting characteristic of the disease is the oval 
 outline which some of the vesicles are apt to assume. The 
 vesicle is formed by the effusion of fluid beneath the horny 
 cuticle. Where the skin is thrown habitually into folds or 
 wrinkles the cuticle is stripped more easily in the direction of 
 the fold than across it, and the vesicle tends to increase in 
 the one direction more than in the other. Vesicles of this 
 shape, therefore, are most likely to be met with in situations 
 where the creasing is pronounced ; that is to say, in the neigh- 
 bourhood of the flexures; and the long diameter of the 
 vesicle will lie in the direction of the crease. (Plate cix.) 
 A peculiarity which may be observed still more fre- 
 quently is that many of the vesicles have not so much an
 
 120 THE DIAGNOSIS OF SMALLPOX 
 
 oval as a jagged or irregular outline. (Plate CVIIL, Fig. 2.) 
 The same explanation holds good, probably, tor all these 
 deviations from the circular shape : the resistance to the 
 expansion of the vesicle is different in different directions, on 
 account of the criss-cross of lines and wrinkles into which the 
 skin habitually falls. 
 
 That an oval or irregular outline is less frequently 
 displayed by the vesicles of smallpox is due, doubtless, to the 
 circumstance that among the deeper strata of the skin the 
 wrinkling of the surface would have less influence in modify- 
 ing the equal expansion of the vesicle. Yariolous vesicles, at 
 any rate, are more liable to depart from the circular outline 
 when they are unusually superficial (Plate CVIIL, Fig. 1.) 
 For the reason that sometimes they do so depart, the 
 evidence irom outline must not be pressed too far ; such 
 evidence, indeed, is merely additional evidence of position. 
 Yet an elongated outline to some of the lesions is evidence of 
 chickenpox which is especially useful when the patient has 
 not come under observation until the lesions have become 
 encrusted and the other characteristics have become obscure. 
 
 With regard to all these signs it must be remembered 
 that the extent to which they can be relied upon depends 
 upon the prominence which they may attain. Cases of 
 modified smallpox occur, exceptionally, in which all the 
 lesions, or most of them, display a character more appropriate 
 to chickenpox. On the other hand, lesions of chickenpox are 
 to be encountered which are every bit as deep as those seen 
 in very many cases of smallpox. Chickenpox often leaves 
 scars, and what better proof could there be of the depth to 
 which its lesions may penetrate ? But in cases of each 
 disease it happens generally that, though in places the 
 character of the lesions may be discordant, yet on the whole 
 the trend of evidence is in the right direction. 
 
 Two other minor characteristics distinguish the eruption 
 of chickenpox : the absence of umbilication of the vesicles 
 and the efflorescence of vesicles in successive crops, or, in 
 other words, the presence of lesions in different stages of 
 evolution. A lack of homogeneity among the lesions must
 
 CHICKENPOX 121 
 
 not always be expected of chickenpox ; and, when it exists, 
 is not necessarily valid evidence against smallpox. The 
 aggregation of lesions of a different age tells against the latter 
 only under the conditions detailed in Chapter VIII. (p. 51). 
 Indentation of a number of vesicles is good evidence against 
 chickenpox, but not the dimpling of a few. The absence of 
 this sign counts nothing either way. 
 
 Distribution. As there is no part of the body on which the 
 lesions of smallpox may not appear, so there is no part which 
 is incapable of developing the vesicles of chickenpox. They 
 may come on any part of the trunk, limbs, and head, on the 
 palms and the soles, the scalp and the ears, the palate and 
 the buccal mucous membrane. Nevertheless, the rash, hardly 
 less than that of smallpox, shows its individuality by the 
 choice of favourite situations. 
 
 The seat of election is the trunk of the body, and the rash 
 may be limited to that part almost entirely. More often it 
 comes also on the face ; and sometimes is as dense there as on 
 the trunk. (Plates ex., cxi., cxn.) Smallpox chooses the 
 face before all, next the arms, thirdly the back or legs. 
 While smallpox least affects the front of the trunk, the 
 eruption of chickenpox is often as abundant there as on the 
 back, or more abundant. While the variolous rash is more 
 abundant on the shoulders than over the loins, and more 
 abundant on the chest than on the abdomen, that of chicken- 
 pox displays no such constant difference. Unlike smallpox, 
 chickenpox tends to avoid the limbs, and if the rash affects 
 them, it shows no preference for the extensor surfaces. Its 
 density, besides, increases from below upwards the distri- 
 bution is centripetal ; whereas with smallpox the density 
 increases, from above downwards the distribution is centri- 
 fugal. The larger and better developed variolous spots come 
 at the ends of the limbs where the rash is densest ; with 
 chickenpox, on the contrary, vesicles which occur at the ends 
 of the limbs tend not only to be sparse, but also to be small 
 and ill developed. 
 
 In applying these considerations to a particular case, it is 
 necessary to weigh the evidence as a whole and not to seize
 
 122 THE DIAGNOSIS OF SMALLPOX 
 
 upon one part of it as being essential. Both diseases have 
 anomalies of distribution. In the milder and more modified 
 cases of smallpox, for instance, it happens sometimes that the 
 upper limbs or the lower carry less than their wonted share 
 of the rash, and that it is disposed after a fashion which is 
 centripetal rather than centrifugal. Yet the disposition of the 
 rash over the rest of the body will conform to the usual law. A 
 case of chickenpox may be remarkable because the rash is 
 unusually abundant on the limbs (Plate CXIIL); or because, 
 although the rash is scanty on the limbs, a few well-developed 
 vesicles or pustules are seen at their extremities, for example 
 on the hands or soles. But the presence of a rash of some 
 density on the limbs, or of a few fat pustules on the hands or 
 soles, is by no means inconsistent with chickenpox. Again, 
 it is unusual in cases of chickenpox for the rash to be much 
 denser on the face than on the trunk of the body, or for it to 
 be much denser on the back than on the front of the trunk, 
 or denser on the shoulders or on the chest than over the loins 
 or on the abdomen. (Plates xxix. and cxn.) Yet those 
 events, happening singly, would not upset the balance of 
 evidence. Similarly, smallpox is more apt than chickenpox 
 to affect the buccal mucous membrane ; but with chickenpox 
 a few vesicles are to be encountered very commonly in that 
 situation, and occasionally they are present in some abundance. 
 It is to be remembered that the eruption of chickenpox 
 is more liable than that of smallpox to be unstable or capri- 
 cious in distribution. The rash has affinities, but the bonds are 
 readily stretched or broken. It is less unusual, therefore, for 
 chickenpox to deviate so far from the type as to mimic the 
 distribution of smallpox than for a variolous rash to approach 
 closely to the common pattern of chickenpox. (Plate CXIIL) 
 Occasionally chickenpox imitates smallpox even by responding 
 to cutaneous irritation. (Plate xxxvi., Fig. 1.) Yet, however 
 specious may be the general similarity displayed by such 
 anomalous cases, there will be material outstanding differ- 
 ences. The gradations in density, for instance, though right 
 in kind may be insufficient in degree ; the rash will not be 
 shy of the armpits and groins ; nor will it map out the con-
 
 CHICKENPOX 123 
 
 tours of the surface on the face, the neck, the bust, or on 
 other parts of the body. (Plates xxix., CXIL, and cxiv., 
 Fig. 1.) All these points, which are .of great importance to 
 the differentiation of the two diseases, have been fully dis- 
 cussed in earlier chapters. 
 
 When the eruption is scanty, difficulties in diagnosis begin 
 to arise ; for then the evidence from distribution is less com- 
 plete. If, at the same time, the lesions should be small and 
 should have become encrusted, circumstances under which 
 their character may be difficult to appreciate, the trouble 
 then may be formidable. In such event, it is probably safer 
 to be guided by the disposition of the few spots that can be 
 seen, than by the character which they may be assumed to 
 possess. (Plate xxxvi., Fig. 2.) It is only in such cases that 
 it is right to be much influenced by that circumstantial 
 evidence from which it is so difficult to turn the mind the 
 presence or absence of either disease in the neighbourhood, 
 the age of the patient, and his state in respect of vaccination. 
 
 Summary. To conclude this account, the chief points of 
 difference between the two diseases are enumerated in the 
 following summary : 
 
 SMALLPOX CHICKENPOX 
 
 1. The rash is most abundant on 1. The abdomen and chest are 
 the face ; most scanty on the covered as thickly as the face, 
 abdomen and chest. or more thickly. 
 
 2. The rash is much more - The abdomen is covered 
 abundant on the back than on the equally with the back, 
 abdomen. 
 
 3. The rash is more abundant 3. The distribution is indif- 
 on the shoulders than across the ferent. 
 
 loins, and on the chest than on 
 the abdomen. 
 
 4. The rash favours the limbs ; 4. The rash tends to avoid the 
 and, generally, the arms next to limbs. 
 
 the face. 
 
 5. The distribution on the limbs 5. The distribution on the limbs 
 is centrifugal. is centripetal. 
 
 6. The rash favours prominences, 6. The rash behaves indiffer- 
 and surfaces exposed to irritation ; ently. 
 
 it tends to avoid protected sur- 
 faces, flexures, and depressions.
 
 124 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 SMALLPOX continued. 
 
 7. The lesions are deep-seated, 
 and have an infiltrated base. 
 
 8. The lesions are generally 
 circular in outline. 
 
 9. The lesions are homogeneous 
 in character ; or, if they are 
 heterogeneous, they are hetero- 
 geneous by law (Chapter YIIL, 
 p. 52). 
 
 10. The vesicles, generally, are 
 multilocular. 
 
 11. Frequently some of the 
 vesicles are indented. 
 
 CHICKEXPOX continued. 
 
 7. The lesions are superficial, 
 and the base is not infiltrated. 
 
 8. The lesions frequently have 
 an irregular outline ; when they 
 lie near a flexure, they are apt to 
 be oval or elongated. 
 
 9. The lesions, often, are not 
 homogeneous ; and the want of 
 homogeneity bears no relation to 
 the sizes of the lesions and to their 
 situation. 
 
 10. The vesicles, generally, are 
 unilocular. 
 
 11. The vesicles are never in- 
 dented and seldom dimpled.
 
 PLATE CVIII. 
 
 In Fig. 1 the lesions represented were those of smallpox, in Fig. 2 of cbickenpox. The 
 variolous lesions were very superficial, and comparable in that respect with vesicles 
 of chickenpox. Evidence of this shallowness of position is indicated in the print by 
 the steep edges, and by the elongated or irregular outline of many of the vesicles. 
 Those appearances were displayed still more distinctly by the lesions depicted in 
 Fig. 2. The print illustrates a very characteristic feature of the vesicles of chicken- 
 pox, their outline being very irregular, or sinuous, or jagged.
 
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 PLATE CXI. 
 
 This illustration and the next are from photographs of the same patient. He 
 had chickenpox, and the rash was particularly abundant. It was dis- 
 tributed uniformly and indifferently on the face, back, flanks, chest, and 
 abdomen ; a plan of distribution in striking contrast with that followed by 
 smallpox. The upper extremities were unusually well provided, but the 
 rash diminished in density from above downwards, and was as abundant on 
 the flexor surfaces of the limbs as on the extensor surfaces.
 
 PLATE CXII. 
 
 From the same case as Plate cxi. It will be noticed that the rash was distributed 
 indifferently on the face and invaded the orbit. It invaded also the arm- 
 pit, the suprasternal notch, and the posterior triangle of the neck.
 
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 CHAPTER XVI 
 SYPHILIS VACCINIA 
 
 Syphilis. This disease, which mimics all things, mimics 
 smallpox ; and though it furnishes some of the easiest, 
 furnishes also the most difficult cases to distinguish. In most 
 cases the patient presents a papular or a pustular eruption. 
 The syphilitic roseola, as might be supposed, is not often 
 mimetic. Vesicular syphilides, though uncommon, might 
 reasonably be expected, when they do occur, sometimes to 
 pass themselves off as variolous eruptions; the more so as 
 one variety has been distinguished by the epithet "varioli- 
 form." Yet such a tendency does not appear to exist, or is 
 exhibited but rarely. 
 
 The roseola, the earliest of the secondary syphilides, con- 
 sists of macules or erythematous blotches scattered, mostly, 
 over the front part of the trunk and the flexor surfaces of the 
 limbs. In that guise it is, therefore, wholly unlike a papular 
 variolous rash, either in character or in distribution. Yet there 
 are cases in which the macules are smaller, more prominent, 
 profusely developed and covering almost the whole surface 
 of the body including the face. If such an eruption be 
 ushered in or accompanied by fever and febrile symptoms, 
 as may very well be the case, a precipitate observer might 
 suppose that he had to do with an acute specific fever, and 
 make a diagnosis of measles or of smallpox. With syphilis 
 in the mind, it is not difficult to detect the imposture. The 
 chancre, it may be, has only to be looked for ; and commonly 
 there are not wanting other characteristic signs. Smallpox, 
 at any rate, can be readily eliminated by the softness of the 
 lesions, if not by their size, by their lack of uniformity of 
 character, and by the anomalies of distribution which are no 
 less obvious when the rash is profuse than when it is scanty. 
 
 125
 
 126 THE DIAGNOSIS OF SMALLPOX 
 
 With many examples of papular and pustular syphilo- 
 derms the rash is of sudden development, and, if abundant, 
 its outcrop is not infrequently attended by noteworthy consti- 
 tutional symptoms. It may happen, therefore, with these 
 eruptions, as with the roseola, that the general character of 
 the illness may be something after the style of an acute specific 
 fever. In other cases the facts are not so ; and in all cases 
 the sequel differs from the after-history of a case of smallpox. 
 Yet, for reasons which will be discussed in the next chapter, 
 such considerations may be of little practical value at the 
 moment ; and though they may find their application in suit- 
 able circumstances, it will not be worth while to be occupied 
 with them here. 
 
 Of the papular syphilides some examples figure in the 
 illustrations. (Plates cxiv., Fig. 2, cxv. and cxvi.) The rash 
 may be profuse and may cover almost the whole body, but its 
 incidence is frequently limited and it is apt to be disposed in 
 patches. Unlike the roseola, the papular syphilide frequently 
 affects the face, and in that respect resembles smallpox ; but 
 there is never a close resemblance in the incidence of the 
 eruptions of the two diseases. In some cases the individual 
 papules approximate in character to the variolous papule ; 
 and if attention be concentrated on that circumstance to the 
 exclusion of other evidence, the fact may be found deceptive. 
 Yet in most cases distinguishing characteristics are not want- 
 ing to the lesions ; such as their size or their shape syphilitic 
 papules are apt to be eccentric in outline and flat- topped 
 the presence of scales, the colour, or the association with such 
 exotic lesions as nodules or tubercles or squames. 
 
 Most frequently the syphiloderm to be distinguished con- 
 sists chiefly or entirely of pustular lesions. (Plates cxvu. 
 and LXVI.) As with the papular syphilides, so with the 
 pustular, the discrimination is easy in proportion as the lesions 
 are polymorphous. Sometimes a few discordant lesions, like 
 ulcers or rupial crusts, may be detected among the rest ; and 
 though such pronounced polymorphism may be absent, still 
 there may be too much diversity of character. The lesions 
 of smallpox are not always homogeneous; but it would be
 
 SYPHILIS 127 
 
 against such a diagnosis to find pustules and well-developed 
 papules co-existing, or small pustules lying side by side with 
 large crusts. Again, some of the pustules may be too large, 
 or there may be too much diversity of size, or some of them 
 may be too irregular in outline. 
 
 The position in the skin which the lesion occupies is 
 important to determine, and may be a valuable distinguishing 
 feature. A syphilitic sore, especially if it is not lacking in 
 size, may dip down deeply into the corium or even to the 
 subcutaneous tissue, and may be distinguished by its bulging 
 shape and by the induration about its base. The presence ot 
 even a few lesions of such a character might be distinctive. 
 Less frequently, the pustule is too superficial, being little more 
 than a bleb or crust upon the surface. But most of the 
 lesions of secondary syphiloderms, whether papular or pustular, 
 occupy the papillary layer of the skin or are embedded deeply 
 among the epidermal cells. They occupy, that is to say, a 
 position indistinguishable from that of the variolous lesion. 
 And though, because the inflammatory process is less acute, 
 they may lack resistance to the touch and feel softer than do 
 the papules and pustules of smallpox, yet of such small 
 differences of resistance it is very difficult to make sure. 
 
 The circumstance that the lesions may occupy an in- 
 different position in the skin causes some cases of syphilis 
 to be extraordinarily difficult to distinguish ; but for the 
 difficulty to arise the rash must be scanty. When the 
 eruption is profuse, not only may telling differences of 
 character be found among the lesions, but abundant evidence 
 will be furnished also by their distribution. If, instead of 
 being, as is frequently the case, patchy or elliptical in its 
 incidence, the rash is broad-cast and uniformly indiscriminate 
 in its choice of situation, that lack of discrimination should 
 betray it. And should it happen, as occasionally it must, that 
 the distribution bears in outline a specious resemblance to the 
 variolous pattern, yet even then, unless the rash be scanty, it 
 will be very easy to find discrepancies in points of detail 
 
 Scanty pustular syphilides may be encountered, whose 
 lesions are of uniform character and do not differ materially
 
 128 THE DIAGNOSIS OF SMALLPOX 
 
 from those of many cases of modified smallpox. To distin- 
 guish such cases by the evidence furnished by the eruption 
 alone, it would therefore be necessary to rely wholly upon the 
 distribution. Commonly the rash is either of limited extent 
 or else faulty in its order of choice. But it is clear that 
 occasionally the characteristics of the eruption will be 
 indecisive, and that it will be necessary to cast about for 
 other evidence. The patient may exhibit other symptoms of 
 syphilis, or there may be signs of previous syphilitic eruptions, 
 such as small scars or pigment-marks. An analysis of the 
 personal history may help, but whether the disease be syphilis 
 or smallpox it will be equally unlikely for the constitutional 
 symptoms to have been prominent ; and should the history 
 suggest, or should the patient admit, a past attack of syphilis, 
 it will not follow necessarily that because he has once had 
 syphilis he has not now got smallpox. Fortunately the cases 
 are very exceptional of which the difficulties of diagnosis are 
 so profound. 
 
 Vaccinia. It is more from the difficulty than the fre- 
 quency of the problems to which they give rise that vaccinal 
 eruptions derive their importance. It would seem that there 
 is no temptation to attribute a vaccinal rash to smallpox 
 unless the patient has been exposed to infection from that 
 disease. The usual train of events is that a case of smallpox 
 occurs in a house and that the inmates are successfully 
 re- vaccinated ; after an interval one of them develops an 
 eruption, and the question then arises, is the rash variolous or 
 vaccinal ? 
 
 Before passing to the generalised vaccinal eruptions, the 
 conditions produced by supernumerary vaccine-pustules and 
 the pustules of auto-inoculation deserve a word. It has been 
 shown (Plate I., Fig. 2) that the irritation of a successful 
 vaccine-inoculation, done during the period of incubation of 
 smallpox, is capable of producing a condition which resembles 
 closely that caused by the development of supplementary 
 vaccine-pustules round the place of original inoculation. 
 The event may happen in a case of smallpox even when the 
 eruption is elsewhere so scanty as to concentrate attention
 
 j 
 
 PLATE CXV. 
 
 A papular syphilide. The rash covered the whole body, and the most distinctive feature 
 of its distribution was that all parts were equally affected face, limbs, back, chest, 
 and abdomen. On individual parts of the body, too, there was an absence of those 
 contrasts in density which are to be expected in cases of smallpox. All parts of the 
 back, for instance, were equally affected, and the abdomen equally with the chest.
 
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 PLATE CXVII. 
 
 The print represents a pustular syphilide, and is from the same case as Plate LXVI. 
 The rash invaded all parts of the body, and had a distribution not unlike 
 that of smallpox. The two plates show the resemblance in distribution 
 which was presented by the eruption on the trunk. On the arms, however, 
 the rash had a centripetal distribution, and the flexor surface was affected 
 equally with the extensor. The rash, too, was present in the groins and 
 armpits. The distinction from smallpox was easily made also from the 
 character of the lesions. Many of them were too large, and too irregular 
 in outline, and were heterogeneous in character.
 
 VACCINIA 129 
 
 almost exclusively on the arm. There may be some simi- 
 larity, therefore, between a condition caused by the conjunc- 
 tion of the two causes, smallpox and vaccination, and that 
 caused by vaccination only ; but it is more likely for the 
 former to be mistaken for the latter than the reverse. Vac- 
 cinal pustules of accidental inoculation, occurring elsewhere 
 than in the neighbourhood of the original sore, may be dis- 
 tinguished from ordinary variolous pustules by their irregu- 
 larity of shape and of distribution ; but it may be recalled 
 that smallpox itself may be conveyed accidentally by inocula- 
 tion, for example, from a mother to the child. (Chapter 
 VIII., p. 53.) 
 
 The accidental and unspecific eruptions which occur after 
 vaccination need not be discussed, nor the erythematous 
 rashes of general distribution which are doubtless caused by 
 the circulation in the blood-stream of the secondary products 
 of inflammation absorbed from the vaccine-pustule. But 
 there are to be encountered other generalised eruptions which 
 are composed of distinct elements, and occasionally set 
 problems in diagnosis which are almost insoluble. One 
 difficulty of the matter is occasioned by the rarity of such 
 rashes. It is, at least, to be supposed that they are rare. 
 Public vaccinators appear to have little experience of them, 
 and the accounts in the text-books and periodicals are meagre 
 and unsatisfying. It would not be expected that vaccinal 
 rashes should often be seen in the receiving-room of a small- 
 pox hospital, but they are seen by no means so rarely as the 
 general experience would lead one to suppose. Perhaps the 
 truth is that the rash is so inconspicuous that it escapes 
 attention except when the fear arises that it may, be 
 infectious. 
 
 Wanting better information, generalised particulate vac- 
 cinal rashes may be divided into two groups. In the first 
 may be placed those which are composed of small superficial 
 papules (vaccinal licehn), or of minute vesicles, or of a mixture 
 of these elements. It is probable that these lesions are tox- 
 a3mic, and are not evidence of a generalisation of the specific 
 virus. The subject is generally a child, and the rash may be
 
 130 THE DIAGNOSIS OF SMALLPOX 
 
 quite profuse. The lesions are too small and superficial to be 
 variolous, and there is no tendency to imitate smallpox in 
 distribution. In the second group may be placed eruptions 
 whose elements have a closer resemblance to variolous lesions. 
 Ordinarily the rash is sparse. The lesion may be described 
 as a small pimple with a vesicular or pustular head, superficial 
 in position, but not more so than the more superficial of the 
 lesions which may be encountered in cases of modified small- 
 pox. There is this difference, that with modified smallpox, 
 even with the cases which are exceptionally mild, some of the 
 lesions will be more deeply placed, whereas with vaccinia 
 all are superficial. Yet there remains a difficulty : it cannot 
 be denied that it is possible for a variolous eruption to occur, 
 very scanty and modified to an exceptional degree, all of 
 whose lesions shall be as atypical as those of vaccinia. And 
 assuming a particular case to be an example of smallpox and 
 not of vaccinia, a highly modified eruption would be expected, 
 since the patient, by hypothesis, would have been successfully 
 vaccinated during the period of incubation. Vaccinal 
 eruptions have been recorded which were more abundant, 
 and whose lesions were larger and nearer in character 
 to those of the modified variolous rashes more commonly 
 encountered. There is no reason to question the occurrence of 
 such eruptions ; indeed, their occurrence might be expected ; 
 but they are undoubtedly of the utmost rarity, and the author 
 has had no experience of them. 
 
 Under such circumstances, how can it be decided that the 
 patient has not got smallpox ? Since he must be immune 
 both to smallpox and to vaccinia, no crucial test can be applied. 
 But in some, at least, of these cases the arrangement of the 
 lesions is not such as might be expected if the patient had 
 smallpox. They are prone to affect the trunk, and their 
 distribution is less akin to that of smallpox than to that of 
 chickenpox. It is curious that this should be so, since it 
 seems probable that the vaccinal and variolous eruptions have 
 the same pathology. Should no such distinct difference 
 appear, the case would be best treated as one of the graver 
 disease.
 
 VACCINIA 131 
 
 It may happen that circumstantial evidence opposes a 
 diagnosis of smallpox. If the date of exposure to variolous 
 infection is known, that diagnosis might have to assume too 
 long a period of incubation. If the interval between the 
 exposure and the outcrop were more than sixteen or less 
 than twelve days, the rash would be more likely to be vac- 
 cinal. Or assistance may be derived from the duration of the 
 period between vaccination and the outcrop of the rash. 
 If the outcrop occurred as late as ten days after the date of 
 first reaction to the vaccinal inoculation, the odds against 
 smallpox would be considerable. But the vaccinal eruption 
 is developed, generally, when the local reaction is at its 
 height, that is to say, at the end of the first week after inoc- 
 ulation ; and such an interval is too short to preclude the 
 possibility of the eruption being the bloom of a variolous 
 infection previously ingrained.
 
 CHAPTER XVII 
 DERMATITIS PUSTULAR DERMATOSES 
 
 The less frequent misinterpretations. Besides those der- 
 inatoses, to be noticed presently, which are capable of 
 assuming at least a superficial resemblance to the eruption of 
 smallpox, there are many others which are mistaken rarely, or 
 through accidental circumstances, yet are of considerable 
 importance in the aggregate. 
 
 In many of these cases the patient suffers really from a 
 constitutional disorder. Such a misapprehension, as might be 
 expected, occurs chiefly when smallpox is rife. It may 
 happen, indeed, and often does happen, that the patient has 
 symptoms of illness but never any eruption ; he is certified on 
 suspicion, because he is known to have been exposed to 
 variolous contagion. But we are concerned rather with the 
 patient who is certified in good faith because he suffers from 
 some disorder which is associated with a skin-eruption, but 
 associated by accident. It may seem strange that such 
 diseases as acute rheumatism, acute tuberculosis, or 
 pneumonia should be mistaken for smallpox. Yet to every- 
 one in practice it occurs, at the onset of an acute disease, to 
 have to debate the alternative diagnosis of an acute specific 
 fever. Suppose, then, that a close examination reveals the 
 presence even of a few pimples, freshly developed or not 
 previously noticed ; is it surprising, smallpox being about, 
 that smallpox should sometimes be suspected ? 
 
 In some instances the eruption is really a consequence of 
 the constitutional disorder, though the disease is one which 
 is not usually signalised by an eruption. The affection of 
 the skin will be due, probably, to some contamination of the 
 blood-stream. Thus the patient may be suffering from 
 Bright's disease, complicated, perhaps, by uraemia ; or he may 
 
 132
 
 DERMATITIS PUSTULAR DERMATOSES 133 
 
 be a victim of ulcerative endocarditis or of some other form 
 of pyaemia. It should not be forgotten that a disease which is 
 peculiarly liable to evoke a pustular skin-eruption is diabetes. 
 Occasionally the patient is the subject of a disease of the 
 nervous system, such as acute mania, or cerebral abcess, or 
 meningitis, and the associated eruption may be toxsemic or 
 may possibly be trophic. The mention of the last disease 
 suggests that were epidemic meningitis commoner the 
 eruptions which are a feature of it might sometimes cause it 
 to be mistaken. Another eruptive fever which perhaps 
 owes to its rarity its immunity from a similar misapprehen- 
 sion is glanders. 
 
 On the other hand, the patient may suffer from a skin- 
 disease, uncomplicated, one which in general bears no resem- 
 blance to smallpox and owes its misapprehension to accidental 
 features of its own rather than to its associations. An erup- 
 tion of small boils may be associated with another malady ; 
 but sometimes the patient has no other disorder, and 
 suspicion was aroused by the suddenness of the attack, the 
 presence of febrile disturbance, and the wide dissemination of 
 the lesions. Though herpes zoster is unsymmetrical in 
 distribution, and therefore wholly alien in character, yet it 
 appears with some constancy in a long series of cases of 
 mistaken diagnosis ; in the deceptive cases the eruption is 
 generally of unusual extent and unusual distribution. 
 Another disease occasionally mistaken is pemphigus, the 
 accident being more likely to occur when the bullse are 
 abnormally small. 
 
 The catalogue is not exhaustive, but there would be no 
 object in extending it. In none of the instances is there a 
 close resemblance to smallpox, and no great art is required 
 for the distinction. The diagnosis has often been arrived at 
 by the process of exclusion. But not all the eruptions to 
 which the race is subject are systematised in the text-books or 
 are within the experience of any physician ; and while it may 
 be easy to assert that the patient has not got smallpox, it may 
 be impossible to tell the real disease from which he suffers. 
 
 Antecedent symptoms. In some of the cases suggested
 
 134 THE DIAGNOSIS OF SMALLPOX 
 
 above, the observer has been misled by the associated 
 symptoms. It is not well that, with a pustular eruption, 
 much weight should be attached to these. When an eruption 
 is nascent, or when it is erythematous or hsemorrhagic 
 in character, the associated symptoms, because of the dearth 
 of evidence, may be of importance. But a pustular eruption 
 furnishes evidence which far outweighs that which may be 
 derived from other sources, and, unless they are such as to lift 
 smallpox clean out of the category of possible diseases, the 
 associated or antecedent symptoms are of insignificant value. 
 
 Even the absence of antecedent symptoms counts for little. 
 It will be observed that many of the dermatoses presently to 
 be noticed are afebrile. But in most of those instances the 
 eruption is not very profuse ; and it is by no means un- 
 common for scanty variolous eruptions to be preceded by 
 toxaBmic symptoms which have been evanescent or wholly 
 disregarded. Of what use, then, would it be to instance as a 
 distinguishing feature between smallpox and impetigo, that 
 the eruption is preceded in one case by fever and con- 
 stitutional disturbance but not in the other? Besides, as 
 mentioned before, the association with constitutional disturb- 
 ance of an eruption, ordinarily afebrile, may be accidental. A 
 pustular syphilide may'acquire a specious resemblance to small- 
 pox from the onset of an attack of influenza, or a drug-rash 
 from the symptoms of the disease for which the drug was pre- 
 scribed. 
 
 Still more is it the case that merely the reputed absence 
 of antecedent symptoms is of little moment. The observer, 
 often, has not seen the patient until after the development of 
 the rash and, for the antecedent symptoms, has to rely upon 
 hearsay evidence. Hearsay evidence may be involuntarily 
 deceptive, or it may be, even, that there is a deliberate 
 attempt to deceive. It matters little whether the history 
 relates to the absence of constitutional symptoms or to the 
 duration of the eruption itself. It happens, not infrequently, 
 that it is not sufficient to exclude smallpox that the eruption 
 is of chronic course. A chronic disease must have a begin- 
 ning, and may have a sudden outset ; but the patient, often,
 
 DERMATITIS PUSTULAR DERMATOSES 135 
 
 has been in possession of the rash long enough, if all were 
 known, to put smallpox out of count. The fact is that the 
 circumstantial evidence may be too strong. When smallpox 
 breaks out in a house or institution everyone with a 
 blemished skin is apt to be looked upon with suspicion. That 
 is an attitude which cannot very well be condemned ; but it 
 follows that, in the last resort, everyone must be prepared to 
 distinguish smallpox wholly by the character of the rash. 
 
 Acne. This malady furnishes a striking illustration of 
 some of the preceding remarks. It is chronic, afebrile, de- 
 void of symptoms. Yet, next to chickenpox, it is perhaps 
 the commonest disorder to be mistaken for smallpox. 
 
 Acne, as a rule, is easy to identify by the character of 
 certain of the lesions, and by their limitation to the upper part 
 of the body the face, shoulders, back and chest. (Plate cxix., 
 Fig. 1.) The characteristic acne-spot is deeply rooted in the 
 skin and its base is infiltrated and cedematous, so that the 
 contour of the lesion is that of a broad and shallow cone. 
 (Plate cxvin.) Such lesions are most frequent on the upper 
 part of the back, where they are often associated with black- 
 heads and old scars. But most of the spots, especially those 
 which occur on the face, are more superficial and less 
 characteristic, and they may give a passable rendering of 
 some of the pustules to be found in certain cases of modi- 
 fied smallpox. 
 
 The worst cases are the least likely to be mistaken. 
 The diagnosis may be in doubt, either because no charac- 
 teristic acne-spots and scars are present, or because it is not 
 certain that the patient has not got smallpox as well A 
 close examination may reveal, indeed, certain lesions which 
 could not possibly be produced by acne ; such as vesicles, 
 however small, for acne does not produce vesicles ; flat- 
 topped or hemispherical pustules; or disc-like scabs. Even 
 if no such elements can be detected, the presence of spots 
 on the legs or forearms or hands would be a highly sus- 
 picious circumstance. On the other hand, if the rash had the 
 usual limitation of acne, the presence of a few undoubted 
 acne-spots would almost certainly exclude smallpox; and if
 
 136 THE DIAGNOSIS OF SMALLPOX 
 
 the character of the lesions were wholly in doubt, such a 
 limitation would justify the exclusion unless the rash were 
 of the scantiest proportions, that is to say, composed of a 
 dozen or so of spots. 
 
 Dermatitis. Acute eczema.: In the instances in which 
 this disease is misinterpreted the attack is of sudden 
 onset and involves simultaneously a large portion of the 
 skin. (Plate cxix., Fig. 2.) The patient may be a child or 
 an adult, and may or may not have been previously subject 
 to the malady. It may be, even, that the disease was 
 already present in a chronic form on a part of the skin 
 affected by the fresh attack. (Plate XXVIIL) It more often 
 happens, however, that the disease has appeared for the 
 first time, and has been ushered in by fever and febrile 
 symptoms. In some cases there is the further resemblance 
 to smallpox that the eruption begins with the profuse 
 development of small papules, which rapidly become vesi- 
 cular and pustular. It takes but a short time for the disap- 
 pearance of any resemblance which once existed, and at no 
 stage of the illness can the likeness be considered close. 
 The small size of the lesions in the majority of cases, their 
 superficial position, and the oedema and infiltration of the 
 skin below them, are common distinguishing features. 
 
 Impetigo. It is not always as easy as might be supposed 
 to tell an impetiginous eruption. An eruption of typical 
 character, with wax-like vesicles and amber-coloured adherent 
 crusts, this there is little temptation to confuse. In the more 
 troublesome cases there has been a secondary infection of the 
 follicles producing an eruption of mixed character, of which 
 some of the pustules are deep-seated and may have some 
 resemblance to the less typical variolous pustules. Another 
 cause which tends to increase the difficulty of ultimate 
 classification is that the impetiginous rash may be secondary 
 to another form of dermatitis. Yet the diversity of character 
 among the lesions which may be produced by these causes is 
 a valuable means of distinction from smallpox. Some of the 
 lesions may be obviously exotic, and a common feature is that 
 they are too heterogeneous. (Plate cxxi., Fig. 1.) The most
 
 DERMATITIS PUSTULAR DERMATOSES 137 
 
 difficult cases are those in which the rash is obsolescent and 
 consists only of crusts. Something may still be told by their 
 shape, size, and position in the skin, but the best guide will be 
 their distribution. (Plate cxx.) 
 
 Scabies. The vesicular and pustular eruptions which are 
 secondary to scabies may be puzzling if their cause has been 
 overlooked or put aside. In exceptional cases the eruption is 
 profuse and widely disseminated, and when the subject is very 
 young may even affect the face. The burrows may be 
 difficult to find, but the exact identification of the disease is 
 not of much importance to the issue, since it is seldom 
 difficult to exclude smallpox by the more salient features of 
 the rash. The vesicles evoked by the irritation of the parasite 
 are much more superficial than those of smallpox ; and the 
 inherent eruption is often engrafted with a secondary 
 dermatitis which may cause, as was mentioned in considering 
 impetigo, considerable diversity of character among the 
 lesions, and add to the ease of the distinction. 
 
 Traumatic dermatitis and dermatitis of obscure' origin. 
 A variety of cases may be grouped into this section. As 
 with scabies, the rash may be due to the depredations of 
 parasites or insects, such as mosquitoes or lice. With suscept- 
 ible subjects the bites of mosquitoes sometimes cause a very 
 notable eruption, which may be attended by the formation of 
 vesicles as big as a split pea. In other cases the rash is an 
 occupation dermatitis, or is caused by some form of mechan- 
 ical or chemical irritation. In some instances, though the 
 rash may be suspected to be of traumatic origin, it may be 
 impossible to ascertain the precise cause ; and the observer 
 must be prepared to encounter examples of pustular dermatitis 
 the cause of which completely baffles him. (Plates xxvil. and 
 cxxi., Fig. 2.) It by no means follows that with these 
 unusual or anomalous forms of dermatitis the eruption is 
 always insignificant. It may be profuse or even confluent. 
 Such cases, though disconcerting, are the easiest to distinguish 
 from smallpox. But commonly the rash is scanty, and its 
 only importance lies in the fear that it may be infectious. 
 Each case must be judged on its merits, but it is very seldom
 
 138 THE DIAGNOSIS OF SMALLPOX 
 
 that a variolous origin of the eruption cannot be excluded by 
 the peculiarities of distribution. 
 
 Lichen urticatus. Though this disorder is essentially an 
 urticaria, it may be appropriately mentioned here, since the 
 cases which simulate smallpox do so on account of the 
 secondary eruption of papules or vesicles to which the urti- 
 caria gives rise. The development of vesicles is a very 
 conspicuous feature of certain exceptional cases, and the 
 eruption may be very profuse and widely disseminated. 
 Lichen urticatus occurs chiefly among young children, and it 
 might therefore be held to simulate a highly modified 
 variolous eruption. But the lesions are almost too small and 
 superficial to support that hypothesis, and it is very seldom 
 that they have sufficient uniformity of character. The dis- 
 tribution is wholly unlike, and the malady, of course, is 
 chronic. 
 
 Papular dermatitis. Just as cases of pustular dermatitis 
 are sometimes encountered which cannot be classified, so also 
 may the event be similar when the eruption is papular and 
 never advances beyond the papular stage of development. 
 The eruption may be subacute or chronic. The papules are 
 generally larger than those commonly seen in cases of 
 papular eczema, and are not collected in groups, as with that 
 disease, but are scattered broadcast over the surface as a 
 discrete and somewhat scanty eruption. The incidence of 
 the rash is seldom universal. Some of these cases are prob- 
 ably examples of syphilis, though no evidence of that disease 
 may be forthcoming. Yet sometimes the subjects are 
 children in whose cases syphilis may almost certainly be 
 excluded. Occasionally a patient is certified for smallpox 
 who is found, after a close examination, to be suffering from 
 psoriasis. The mistake is possible only when the rash is in 
 the earliest stage of its development and shows few of its 
 special characteristics. With these cases of papular der- 
 matitis it is evident that time would speedily demonstrate the 
 difference, but it is generally possible to exclude smallpox, 
 without delay, by the incompleteness of the diffusion of the 
 rash and the comparative softness of the lesions.
 
 DERMATITIS PUSTULAR DERMATOSES 139 
 
 Distribution. The enumeration of the members of this 
 group might excite surprise that confusion with smallpox 
 should often be possible. Yet the facts are so ; and it must 
 be remembered that exceptional cases and exceptional cir- 
 cumstances may deceive even practised observers. What 
 makes the discrimination easy is not that the eruptions are 
 alien in the character of their elements, but that their dis- 
 tribution is so seldom consonant with that of the variolous 
 rash. The whole group of eruptions is characterised by a 
 partial, elliptic, or patchy incidence. Acute eczema does not 
 affect the whole cutaneous surface, but certain portions of it 
 suffer for the rest ; the trunk, or the face, or the flexor aspects 
 of the limbs, or a combination of these parts. Impetigo is 
 often limited to the face and extremities, and, when it affects 
 the trunk, the front part suffers rather than the back, the but- 
 tocks rather than the shoulders. Scabies is most likely to 
 affect the forearms, buttocks and legs ; or if the rash comes on 
 the trunk, the lower parts suffer rather than the upper ; the 
 face is rarely affected, and only with children. The favourite 
 situation of lichen urticatus is the lower part of the back and 
 the buttocks ; though the limbs are frequently involved, the 
 face is not so liable to be attacked. Dermatitis from lice is 
 an affection of the covered parts of the body ; from mosquitoes 
 of the uncovered. Psoriasis is a disease of the limbs, not of 
 the face. Such broad distinctions are apparent in almost 
 every case, and, even when the order of incidence is not 
 dissonant, discrepancies in points of detail are not far to seek. 
 Drug-rashes. The only drugs which need be considered 
 are the bromide and iodide salts, both of which produce 
 eruptions having similar characteristics. The lesion begins 
 as a soft papule or as an erythematous macule or blotch. 
 Presently a vesicle is formed, which rapidly becomes pustular 
 and then encrusts. Though alike pathologically, the eruptions 
 encountered in different cases may be of very dissimilar 
 appearance. The lesions may be of almost uniform size, and 
 may not differ materially in size and shape and in their course 
 of evolution from those of smallpox or of chickenpox ; but 
 disparity of size is sometimes a conspicuous feature, and most
 
 140 THE DIAGNOSIS OF SMALLPOX 
 
 or all of the pustules may be a good deal larger than those 
 of smallpox and may bear a closer resemblance to those of 
 pemphigus. Another cause which contributes to the diversity 
 of character among different cases is that the tendency to 
 suppurate is not always so manifest; the evolution of the 
 lesions is then more protracted, and they display an incli- 
 nation to the development of weak granulation-tissue, so that 
 lesions of an acneiform or fungoid character are produced. 
 Such lesions are more characteristic of bromide rashes. 
 Whatever may be their precise character, the pustules are 
 generally superficial in situation and occupy a position in the 
 skin nearer to that of the lesions of chickenpox or of im- 
 petigo ; but that characteristic is not invariably pronounced. 
 The rash is symmetrical, but is apt to be elliptic in distribution 
 and is very frequently patchy, so that it may be confluent 
 in one place and sparse in another. It may be profuse or 
 altogether scanty. 
 
 These variable characteristics conduce, on the whole, to 
 facility of discrimination from smallpox, and the majority of 
 cases cannot very well be confused with that disease. But it 
 is not always so. Plate xxvn., Fig. 1, gives a good idea of 
 the kind of lesion which may have to be distinguished, though 
 in that particular case there was no evidence to show that the 
 rash was produced by the administration of drugs. An 
 eruption composed of lesions of such a character, but more 
 widely diffused, might require for its separation an intimate 
 knowledge of the characteristics of variolous lesions and of the 
 manner of their arrangement. Given such knowledge, drug- 
 rashes can be differentiated from smallpox nearly always with 
 ease and certainty. In point of fact they are not confused so 
 frequently as might be supposed ; but that circumstance is 
 probably due less to inherent dissimilarity than to the fact 
 that the connection between cause and effect is in most cases 
 known to the observer. If it is not known what drugs, or 
 that any drugs, have been administered, the exact identifi- 
 cation of the rash may be impossible and there may be some 
 scope for the exercise of the imagination.
 
 .25 
 
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 ct * 
 
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 es 
 
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 ^ i
 
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 1-1 
 
 s ;..2 
 
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 1111
 
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 PLATE CXXI. 
 
 Fig. 1. Pustules of impetigo. The print shows that the lesions were irregular in outline 
 
 and heterogeneous in kind. On the arm small pustules could be seen lying among 
 
 larger lesions which had become incrusted. 
 Fig. 2. Pustular dermatitis in the case of a cachectic boy. The rash was uneven in its 
 
 incidence. The bulk of it was on the buttocks ; a few spots were scattered on the 
 
 legs, arms, and elsewhere.
 
 CHAPTER XVIII 
 
 VACCINATION AS A FACTOR IN DIAGNOSIS 
 
 THE last piece of evidence to collect is the condition of the 
 patient relative to vaccination. This should seldom be 
 allowed to outweigh direct evidence as to the nature of the 
 disease, but there are times when it is very pertinent. 
 
 The common tendency is both to underestimate, and to 
 exaggerate the capacity of vaccination to protect against 
 smallpox. Within limits that capacity is incapable of 
 exaggeration. A person successfully vaccinated or re- 
 vaccinated acquires for a time an immunity so complete that 
 a deliberate attempt to acquire smallpox would surely fail. 
 But with some persons such an absolute immunity is rela- 
 tively fleeting, and within a few years will have become 
 sufficiently attenuated for an attack of smallpox to be 
 acquired, though generally but an insignificant attack. 
 
 The briefest possible duration of absolute immunity after 
 vaccination or revaccination may be taken, for practical 
 purposes, to be two years. If a patient, suspected of having 
 smallpox, could furnish undoubted evidence of a successful 
 vaccination within such a period, the evidence against small- 
 pox would be overwhelming. With most persons the duration 
 of absolute immunity is more protracted. A few people 
 acquire a life-long immunity after infantile vaccination ; 
 many persons after one successful revaccination. In rare 
 instances immunity is still impermanent after several success- 
 ful revaccinations. Should the patient display conclusive 
 evidence of successful vaccination within five years, or of 
 successful revaccination within ten, the weight of that 
 evidence would be against his having smallpox. It need 
 hardly be said that unsuccessful vaccinations do not count.* 
 
 * The fact would be difficult of proof, but it is probable that the duration of 
 his vaccinal immunity bears some relation to the subject's inborn susceptibility, 
 
 141
 
 142 THE DIAGNOSIS OF SMALLPOX 
 
 In the application of these considerations much import- 
 ance will attach to the kind of rash which the patient exhibits. 
 With a child of five, vaccinated in infancy, supposing 
 the diagnosis to lie between chickenpox and smallpox, the 
 evidence would tell against smallpox if the pustules were fat 
 and the rash abundant : if the rash were scanty and the 
 pustules small, the evidence would be more equally balanced, 
 even assuming on other grounds an equal probability of either 
 disease ; for though on the one hand a variolous eruption in 
 the case of a young vaccinated child would almost necessarily 
 be scanty and modified, on the other hand the probability of 
 complete immunity to smallpox would be considerable. If 
 the child were unvaccinated, the fact that the rash was 
 abundant and the lesions well formed would count nothing 
 either way unless the rash were actually confluent ; but if the 
 spots were small and scanty the disease would probably be 
 chickenpox. Exceptions will occur now and then in both 
 directions. An unvaccinated child may be insusceptible by 
 nature, and may get an attack of modified smallpox. On the 
 other hand, in rare cases the protection of vaccination or of 
 revaccination suffers complete erosion within five years, and 
 the subject might then be vulnerable even to an attack of 
 confluent or of toxic smallpox. 
 
 In such inquiries it is important to have authentic 
 evidence of the success of the vaccination and of its date. 
 With children the matter is simple enough. The scars of 
 primary vaccination never become obliterated until after the 
 lapse of a good many years. The success of a reputed revac- 
 cination is more difficult to determine. The statements 
 of patients are unreliable to the last degree. Scars of suc- 
 cessful revaccination are often transitory, and sometimes the 
 inoculation, though undoubtedly successful, leaves no scar. 
 It may be difficult to decide, also, whether the existing scars 
 are all infantile or are in part due to revaccination. If the 
 vaccination was recent, the scars will be pigmented. But 
 it must be remembered that a pigmented area, though 
 
 and that a person naturally resistant to smallpox would be likely to acquire by 
 vaccination complete immunity of long duration ; and so conversely.
 
 VACCINATION IN DIAGNOSIS 143 
 
 not a scar, may remain for months after an unsuccessful 
 inoculation. A pigmented or a pink scar may be taken 
 as good evidence that a successful vaccination has been 
 done within two years, and therefore that the patient is in- 
 susceptible. 
 
 Even at the time of vaccination it is often difficult for the 
 operator to decide whether or not he has obtained a success- 
 ful reaction. In cases of primary vaccination it is different, 
 but everyone is familiar with the atypical reactions which 
 may be obtained after revaccination. Operators are some- 
 times too easily satisfied. Though a typical vesicle, or indeed 
 a vesicle of any kind, must not always be expected, it is a 
 great mistake to accept as valid evidence of success an 
 ambiguous inflammatory reaction. Localised redness and 
 swelling of the skin under the seat of inoculation frequently 
 follow an unsuccessful operation, and unfortunately such 
 reactions are sometimes accepted as vaccinal. Such an 
 erroneous assumption may be productive of the most serious 
 risk to the subject. It has happened many times that a 
 person, certified to have acquired protection from recent 
 vaccination, has been proved shortly afterwards to be sus- 
 ceptible to a characteristic vaccinal reaction, a result which 
 would have been impossible had the first operation been 
 successful. When the operation is undertaken on account of 
 exposure to infection of smallpox, a similar mistake may cost 
 the patient dearly. Short of a definite vesicle, the only 
 evidence which should be accepted as indicative of success is 
 a circumscribed, deep-seated, indurated swelling of the skin 
 under the seat of inoculation, developing about three days 
 after the operation ; and such a result should be confirmed 
 by at least one subsequent inoculation. 
 
 If a person has been shown to be really insusceptible to 
 vaccinia, that fact is proof positive that he is insusceptible 
 to smallpox* The test is of importance when there is a 
 suspicion that a mild and unrecognised attack of smallpox 
 
 * The converse proposition does not necessarily hold good, that susceptibility 
 to vaccinia proves previous susceptibility to the infection of smallpox conveyed 
 through the usual channels.
 
 144 THE DIAGNOSIS OF SMALLPOX 
 
 has been sustained by a person who has not previously been 
 vaccinated. The validity of the deduction rests upon the 
 assumption, which for practical purposes may be accepted as 
 true, that no one is born insusceptible to vaccinia.* 
 
 Vaccination after exposure. Germane to this subject is 
 the effect of vaccination done after exposure to infection. 
 Vaccination, done within a day or two after exposure and 
 followed by a normal reaction, is a certain preventive. If 
 postponed until the latter part of the period of incubation it 
 will be ineffectual. 
 
 The duration of the period of incubation, counting to the 
 outcrop of the rash, may be taken as fourteen days. If this 
 period be divided into three intervals comprising seven days, 
 three days, and four days, then it will be accurate, in the 
 main, to say that a successful vaccination done in the first 
 interval will wholly prevent the attack, done in the second 
 will have more or less effect in modifying the eruption, and 
 done in the last will merely add to the patient's troubles. 
 
 But to this rule there are occasional exceptions. A patient 
 may be vaccinated successfully as early as the fourteenth, or 
 even fifteenth, day before the outcrop and yet not escape the 
 disease ; or during the first half of the incubation-period and 
 yet develop an unmodified attack. The fact is, that the 
 pertinent date is not when the subject is vaccinated, but 
 when the reaction begins. Sometimes, through a peculiarity 
 either of the lymph or of the subject, the reaction which 
 should be manifest on the third or fourth day does not begin 
 to arise, it may be, until a week or more after inoculation. 
 In such a case the rise of immunity will be correspondingly 
 deferred. It is for this reason that protection against small- 
 pox can never be promised confidently if its acquisition be 
 postponed until after exposure. 
 
 In another class of cases the exception is more apparent 
 than real. Infants, newly born of variolous mothers, may 
 
 * Infants born of variolous mothers are sometimes insusceptible to vaccinia, 
 and possibly the successful vaccination of the mother shortly before the birth 
 of the child may have, occasionally, a similar effect. But there is reason to 
 suppose that in either case the immunity conferred upon the child is fugitive.
 
 VACCINATION 145 
 
 develop smallpox even though vaccinated immediately after 
 birth. This circumstance is due to the fact that the infection 
 has been derived from the mother in utero. The rash in 
 such cases is developed within ten days of birth, and the 
 vaccination has in reality been done during the period of 
 incubation. 
 
 Except by reason of accidental failure, vaccination can 
 be performed successfully at any time during the greater part 
 of the period of incubation. But after the onset of illness 
 immunity develops rapidly, and after the efflorescence is 
 completed the patient is wholly insusceptible to vaccinia. 
 There is, however, a fallacy to beware of in determining the 
 success of a vaccinal reaction when the operation has been 
 done during the period of incubation. The irritation of the 
 inoculation, even though the operation be unsuccessful, may 
 be sufficient to evoke presently a small cluster of variolous 
 vesicles over the seat of inoculation. The appearance pro- 
 duced is then very similar to that of a successful vaccinal re- 
 action, and may be by no means easy to distinguish from it. 
 
 A chart is reproduced to show how immunity to vaccinia is 
 acquired coincidently with the onset of an attack of small- 
 pox.* 
 
 For its construction the records were collated of a large 
 number of patients who suffered from smallpox, and had been 
 vaccinated either .during the period of incubation or during 
 the first few days of the illness. The percentage of successful 
 results was then plotted on verticals, corresponding to the 
 intervals which elapsed between the dates of vaccination and 
 of outcrop. (Chart xiv.) 
 
 From this chart it is clear that a very good final test 
 against smallpox would be furnished by the successful vacci- 
 nation of a patient with an eruption of doubtful character. 
 If the eruption were three days old or more, the evidence 
 might be regarded as conclusive. But it will be observed that 
 a successful vaccination done on the day of outcrop would not 
 be entirely convincing. 
 
 * Compiled from the hospital records by the author's former colleague, 
 Dr. R. M. Freer. 
 
 K
 
 146 
 
 THE DIAGNOSIS OF SMALLPOX 
 
 
 9* 
 SO? 
 70)1 
 
 ** 
 
 o* 
 
 J0> 
 
 PEKCENTA 
 
 EACT 
 
 CHAKT xiv. IMMUNITY TO VACCINIA ACQUIRED COINCIDENTLY WITH THE 
 ONSET OF SMALLPOX. 
 
 The data used for the construction of the beginning and of the end of the 
 chart are not completely accurate. Done during the first few days of the period 
 of incubation, successful vaccination generally prevents the attack, and there- 
 fore would eliminate from the records the cases of persons so protected. In 
 effect, the proportion of successful results among inoculations done during the 
 first two-thirds of the period of incubation may be assumed to be uniform and to 
 approach closely to one hundred percent., the few unsuccessful results being 
 due merely to accident. On the other hand, after the outcrop of the rash the 
 percentage of successful results obtained was really much less than would appear 
 from the chart. This fact is due to the circumstance that the records were not 
 made for the purpose of these deductions. Unsuccessful vaccination after the 
 outcrop, in an undoubted case of smallpox, is of no clinical interest, and in 
 many cases the fact was not recorded. The line of susceptibility should fall 
 near to the base-line on the first day of efflorescence, and become extinguished 
 on the third. One successful reaction was recorded for the fourth day, but was 
 open to question. 
 
 SMALLPOX AFTER A PREVIOUS ATTACK 
 
 A patient who has once had smallpox is generally insus- 
 ceptible to a second attack. But second attacks are not rare,
 
 SECOND ATTACKS 147 
 
 though they are much more uncommon than reputed second 
 attacks. Many patients with smallpox assert a previous 
 attack, but furnish no evidence in support of the statement. 
 In most of such cases the historical illness was probably 
 chickenpox. Even when the patient is scarred, there is often 
 no more than a presumption that the scars are variolous. 
 When the evidence of the first attack is trustworthy, it will 
 be found almost invariably that the interval between the two 
 arracks has been a long one and that the second attack is 
 mild. Instances in which a patient, displaying undoubted 
 evidence of a previous attack, dies of confluent or of toxic 
 smallpox are excessively rare. 
 
 If reputed second attacks are to be looked upon with a 
 critical eye, what of relapses and recurrences ? Many such 
 are on record. But the burden of proof which is on the 
 recorder is a little too lightly borne. Nature is not prodigal 
 of her prodigies ; and each of us may with confidence regard 
 such an incident in his practice as furnishing presumptive 
 evidence of one error of diagnosis.
 
 INDEX 
 
 Abortion, 78. 
 
 Abscesses, a sequela of smallpox, 56. 
 
 Acne, 13f> : lesions of, 31, 135. 
 
 Acute febrile erythema, 113. 
 
 Adenitis, 100, 108. 
 
 Air-passages, haemorrhage affecting, 
 
 78, 79 ; morbid pathology of, 100 ; 
 
 the eruption in, 20. 
 Albuminuria, 91. 
 Alimentary tract, morbid anatomy of, 
 
 100. 
 
 Areola of lesion, 27. 
 Anns, distribution on, 13, 15, 16, 19. 
 Attire, influence of, on distribution, 6. 
 
 Birdwood on the pathology of small- 
 pox, 8. 
 
 Blebs, surrounding variolous lesions, 
 53. 
 
 Blood, changes with toxic smallpox, 
 101. 
 
 Blood-poisoning, a mis-diagnosis in 
 cases of toxic smallpox, 103. 
 
 Boils, a sequela of smallpox, 56 ; mis- 
 taken for smallpox, 133. 
 
 Boot, irritative effect of, 7, 11. 
 
 Bright's disease, 103, 132. 
 
 Broncho-pneumonia, a cause of death, 
 39. 
 
 Bruises, 75, 78. 
 
 Catarrh, 60, 71 ; with acute febrile 
 erythema, 114, 116; with measles, 
 105. 
 
 Cerebral disease, mistaken for 
 smallpox, 133. 
 
 Chickenpox, 117 et seq. ; age-inci- 
 dence of, 117 ; distribution in the 
 case of, 121 ; irritation-patches 
 with, 24, 122 ; lack of homogeneity 
 among lesions of, 51, 120 ; papules 
 of, 118 ; position in skin of lesions 
 of, 31, 119, 120 ; pre-emptive 
 period of, 117; prodromal rashes 
 with, 118 ; shape of vesicles of, 53, 
 119. 
 
 Clinical cases with symptoms of 
 haemorrhage, 79. 
 
 Collapse, with toxic smallpox, 87, 91. 
 
 Collar, irritative effect of, 7. 
 
 Confluent eruptions modified, 45. 
 
 papular eruption, 40 ; measles 
 
 mistaken for, 106. 
 
 smallpox, 33 et seq. ; aspect of 
 
 patient with, 36; recession of 
 pyrexia with, 36 ; suppura- 
 tive fever with, 38 ; termina- 
 tion in cases of, 39 ; toxsernic 
 fever with, 33, 63. 
 
 vesicular eruption, 41, 42. 
 
 Conjunctiva, haemorrhage into, 78 ; 
 
 injection of, 60, 71, 105. 
 
 Connective tissue, extravasations in, 
 with toxic smallpox, 101. 
 
 Corsets, effect of, on distribution, 7, 
 19. 
 
 Crusts, 27, 54; of chickenpox, 119; 
 of impetigo, 136 ; rupial, 126. 
 
 Curschmann on toxic smallpox, 85. 
 
 Cutaneous stimulation, effect on dis- 
 tribution of exposure to and pro- 
 tection from, 9, 10 ; with chicken- 
 pox, 122. 
 
 119
 
 150 
 
 INDEX 
 
 Delirium, with the secondary fever, 
 39 ; with the toxaemia, 60 ; with 
 toxic smallpox, 87. 
 
 Dermatitis, a medicament is, 139 ; 
 papular, 138 ; traumatic, 137. 
 
 Desquamation, 55. 
 
 Diabetes, 133. 
 
 Diarrhoea, with acute febrile erythema, 
 114. 
 
 Diphtheria, 103. 
 
 Discrete smallpox, 39. 
 
 Distribution, 6 et seq. ; anomalies of, 
 18 ; faulty, or lack of gradation in, 
 22 ; general scheme of, 14 ; in- 
 fluence of attire on, 6 ; influence 
 of exposure to or protection from 
 cutaneous stimulation on, 9, 10 ; 
 of acne lesions, 135 ; of chicken- 
 pox rashes, 121 ; of drug-rashes, 
 140 ; of eruption of measles, 107 ; 
 of eruption of typhus, 109 ; of 
 immature rash, 23, 33 ; of meagre 
 rashes, 25 ; of pustular dermatoses, 
 139; of simple erythemata, 111, 
 113, 115 ; of syphilitic rashes, 125 ; 
 of toxaemic petechial rashes, 67 ; 
 of toxaemic rose-rashes, 70 ; of 
 vaccinal rashes, 130 ; on the ear, 
 17 ; on the face, 14, 16 ; on the 
 foot and hand, 11 ; on the neck, 
 17 ; on the trunk and limbs, 15, 
 18, 19 ; on the scalp and air- 
 passages, 20. 
 
 Ear, distribution on, 17. 
 Eczema, acute, 136. 
 Endocarditis, nlcerative, 103, 132. 
 Enteric fever, 108 ; purpura with, 
 
 103, 108. 
 Epistaxis, 78. 
 Eruption, see " Rash." 
 Eruptions, see " Rashes." 
 Eruptive fever, 33 et seq. 
 Erythema, acute febrile, see " Acute 
 febrile erythema." 
 
 bullosum, 110. 
 
 iris, 111. 
 
 Erythema multiforme, 111 ; and acute 
 febrile erythema, 113; with 
 formation of vesicles, 112; 
 with urticarial lesions, 112. 
 
 nummulare, 110. 
 
 papulatum, 112. 
 
 rheumaticum, 110. 
 
 Erythematous toxaemic rashes, see 
 
 " Toxaemic rose-rashes." 
 Eyes, affections of, complicating small- 
 pox, 56; suffusion of, 60. 
 
 Face, distribution on, 14, 16. 
 Facial expression, with confluent 
 
 smallpox, 36 ; with toxic smallpox, 
 
 86. 
 Fauces, congestion of, with toxic 
 
 smallpox, 79, 99, 103. 
 Felix on the pathology of smallpox, 
 
 8. 
 
 Focal lesion, definition of, 2 ; of 
 smallpox, see " Lesion." 
 
 rashes, see " Rashes." 
 
 Fcetor with toxic smallpox, 90. 
 Foot, distribution on, 11. 
 Freer on immunity to vaccinia 
 developing with the onset of small- 
 pox, 145. 
 
 Garter, irritative effect of, 7. 
 Glanders, 133. 
 Gramilomata, 48, 55. 
 
 Haematemesis, 79. 
 
 Haematuria, 79. 
 
 Haemoptysis, 79, 92. 
 
 Haemorrhage, post-toxaemic, 74 ; af- 
 fecting the pustules, 75. 
 
 , toxaemic, 75 ; about the lesions, 
 
 76, 77, 95 ; conjunctiva!, 78 ; 
 cutaneous, 76 ; from the 
 gums, 79 ; from the kidneys, 
 79 ; from the lungs, 79, 92 ; 
 from the stomach and bowel, 
 79 ; nasal, 78 ; orbital, 78 ; 
 symptoms of, with toxic 
 smallpox, 96 ; uterine, 78.
 
 INDEX 
 
 151 
 
 Haemorrhagic smallpox, see " Toxic 
 smallpox." 
 
 symptoms of smallpox, 73 et 
 
 seq. ; cases illustrative of, 79 ; I 
 pathology of, 74. 
 
 Hand, distribution on, 12, 19. 
 
 Headache, of toxaemia, 59 ; with 
 acute febrile erythema, 114; with 
 toxic smallpox, 86. 
 
 Heart -failure, 87, 91. 
 
 Hebra on the alleged identity of small- 
 pox and chickenpox, 1. 
 
 Herpes zoster, 133. 
 
 Heterogeneous eruptions, 51 ; of 
 chickenpox, 51, 120 ; of impetigo, 
 136; of scabies, 137; of syphilis, 126. 
 
 Hyperpyrexia, with toxic smallpox, 
 89. 
 
 Immunity, due to previous attack of 
 smallpox, 146 ; due to vaccination, 
 44, 63, 141 ; natural and acquired, 
 43 ; to vaccinia acquired coinci- 
 dently with the onset of smallpox, 
 1 4f> ; to vaccinia implying insus- 
 ceptibility to smallpox, 143. 
 
 Impetigo, 136. 
 
 Incubation-period, 61. 
 
 Influenza, 59. 
 
 Initial rashes, see " Toxaemic rashes." 
 
 Intrapustular haemorrhage, 7">. 
 
 Intrauterine infection, 84, 97, 145. 
 
 Intravesicular haemorrhage, 77. 
 
 Irritation-patches, 6 ; pathology of, 
 7 ; with chickenpox, 24, 122 ; with 
 other exotic eruptions, 24. 
 
 Kidneys, morbid anatomy of, 100. 
 Koplik's spots in diagnosis, 106, 116. 
 
 Lacrymation, 60. 
 
 Leg, distribution on, 15, 19. 
 
 Lesions (variolous), aberrant, 30, 41, 
 95 ; areola of, 27 ; blebs surround- 
 ing, 53 ; characteristics of modified, 
 47 : evolution of, retarded by tox- 
 aemia, 42, 94 ; granuloma-like, 48, 
 
 55 ; histology of, 28 ; in cases of 
 toxic smallpox, 41, 95; involution 
 of, 27 ; life-history of, 26 ; of in- 
 oculation, 53 ; obsolescent, 54 ; 
 position of, 31 ; shape of, 31, 52 ; 
 size of, 27, 52. 
 
 Lichen, vaccinal, 129 ; urticatus, 138. 
 
 Limbs, distribution on, 15, 19. 
 
 Liver, enlargement of, 91, 103 ; 
 morbid anatomy of, 101. 
 
 Loculation of vesicle, 28 ; absence of, 
 with chickenpox, 119. 
 
 Lumbar pain, 59, 86. 
 
 Lungs and air-passages, morbid 
 anatomy of, 100. 
 
 Malleoli, distribution on, 12. 
 
 Mania, 60 ; acute, mistaken for small- 
 pox, 133. 
 
 Measles, 104 et seq. ; catarrhal symp- 
 toms of, 60, 105, 116 ; diagnosis of, 
 from acute febrile erythema, 115; 
 distribution of immature rash of, 
 23, 107 ; rash of, resembling papular 
 variolous eruption, 40, 106, 107 ; 
 resembling toxaemic erythema, 71, 
 107 ; resembling toxic erythema, 
 99, 107. 
 
 Melaena, 79. 
 
 Melancholia, 60. 
 
 Meningitis, 59, 133. 
 
 Menstruation, in cases of smallpox, 78. 
 
 Mental symptoms, with the toxaemia, 
 60 ; with toxic smallpox, 87. 
 
 Modified smallpox, 43 et seq. ; char- 
 acteristics of lesions of, 47 ; defin- 
 ition of, 43 ; diagnosis of, 48 ; 
 diagnosis of, from vaccinia, 130 ; 
 influence of vaccination in relation 
 to, 44, 144 ; in mild epidemics, 49 ; 
 in toxic cases, 93 ; pathology, 43, 
 44 ; suppurative fever of, 39, 46 ; 
 with confluent eruption, 45 ; with 
 eruption incompletely modified, 46. 
 
 Morbid anatomy, 100. 
 
 Morbillif orm toxaemic rash, see " Tox- 
 aemic rashes.'* 
 
 Mucous membrane of mouth and air-
 
 152 
 
 INDEX 
 
 passages, distribution on, 20 ; haem- 
 orrhage affecting, 78, 79 ; morbid 
 anatomy of, 100. 
 
 Muscular atony with toxic smallpox, 
 86. 
 
 Mustard-leaf, irritative effect of, 6. 
 
 Neck, distribution on, 17. 
 Nephritis, 103, 132. 
 
 Odour of toxic smallpox, 90. 
 (Edema of the lungs, 79, 91, 100. 
 Outcrop of eruption, 23, 33, 61 ; 
 
 delayed in toxic cases, 94. 
 Outline of lesions, of smallpox, ~r2, 
 
 120 ; of chickenpox, 52, 119. 
 
 Pain, with acute febrile erythema, 
 114; with the toxaemia, 59 ; with 
 toxic smallpox, 86. 
 
 Papules, formation of, 26 ; of chicken- 
 pox, 1 18 ; size of, 27 ; tactile im- 
 pression of, 29 ; see also under 
 " Lesions." 
 
 Pathology of smallpox, 7. 
 
 Pemphigus, 133. 
 
 Period of incubation, 61. 
 
 Petechiae, 76 ; with enteric fever, 108 ; 
 with toxic smallpox, 97. 
 
 Petechial or purpuric toxaemic rash, 
 see under " Toxaemic." 
 
 Pigmentation, 55, 75. 
 
 Pleurisy with toxic smallpox, 100. 
 
 Pneumonia, mistaken for smallpox, 
 59, 132 ; with toxic smallpox, 92. 
 
 Post-mortem signs of toxic smallpox, 
 100. 
 
 Post-toxaemic haemorrhage, 74. 
 
 Pre-emptive period, 61, 94 ; with 
 chickenpox, 117. 
 
 Prodromal rashes, see " Toxaemic 
 rashes." 
 
 Proptosis of eyeball, 78. 
 
 Prostration, 59 ; with acute febrile 
 erythema, 1 14 ; with toxic small- 
 pox, 86. 
 
 Protopapules, 53. 
 
 Psoriasis, 138. 
 
 Purpura, simple, 110: with enteric 
 fever, 103, 108. 
 
 variolosa, 85, footnote. 
 
 Pustular dermatoses associated with 
 
 certain constitutional disorders, 132, 
 
 133. 
 Pustules, formation of, 27 ; size of, 
 
 27; see also under "Lesions." 
 Pyaemia, 133. 
 Pyrexia, with acute febrile erythema, 
 
 114; with chickenpox, 117; with 
 
 scarlet fever, 100 ; with smallpox, 
 
 33 et seq. ; with the toxaemia, 59 ; 
 
 with toxic smallpox, 87. 
 
 Rash, focal (of smallpox), confluent, 
 see " Confluent smallpox " and 
 . " Confluent eruptions " ; desqua- 
 mation caused by, 55 ; diagnosis 
 of when meagre, 25 ; discrete, see 
 " Discrete smallpox " ; distribu- 
 tion of, see " Distribution " ; evolu- 
 tion of, 35, 52; in toxic cases, 41, 
 77, 95 ; involution of, 39 ; matura- 
 tion of, 36; modified, see "Modi- 
 fied smallpox " ; obsolescence of, 
 .~>4 : of aberrant character, 30, 41, 
 95 ; of heterogeneous character, 
 51 ; outcrop of, see " Outcrop " ; 
 pigmentation following, "'"-. 76 : 
 scars caused by, 54 ; see also under 
 " Lesions." 
 
 Rashes, exotic, irritation-patches with, 
 24 ; their distinction from 
 smallpox, by distribution. 2\ 
 et seq., when immature, _U, 
 when lacking in gradation, 
 ^2. when meagre, 25. 
 
 , focal and toxaemic, definition 
 
 of, 2 ; occurring with small- 
 pox, 3. 
 
 , septic, 56. 
 
 , toxaemic, of smallpox, see 
 " Toxaemic rashes." 
 
 , toxic, 97 ; see also " Toxic 
 
 erythema." 
 
 Relapses and recurrences, 147. 
 Revaccination, evidence of successful
 
 INDEX 
 
 153 
 
 142, 143 ; immunity acquired by, 
 141. 
 
 Rheumatism, acute, 59, 132. 
 
 Rolleston on accidental rashes of 
 chic ken pox, 118. 
 
 Rose rashes, of smallpox, see "Tox- 
 aemic rashes." 
 
 it-, of enteric fever, 108. 
 
 Roseola, syphilitic, 12.">. 
 
 Rubella, 108. 
 
 Salivation, 60. 
 
 Scabies, 137, 
 
 Scabs, 27, .")4 : of chickenpox, 119 ; 
 of impetigo, 136; of syphilis, 12<>. 
 
 Scalp, distribution on, 20. 
 
 Scarlatiniform toxaemia rash, see 
 " Toxu'inic rashes." 
 
 Scarlet fever, 69, 71, 99, 108. 
 
 Scars, 54. 
 
 Second attacks of smallpox, 146. 
 
 Secondary fever, 4, 37. 
 
 Seeds, 64. 
 
 Septic absorption, a cause of death, 
 39. 
 
 rashes, 56. 
 
 Serous surfaces, morbid anatomy of, 
 101. 
 
 Sleeplessness with the toxaemia, 60. 
 
 Spleen, enlargement of, 91 ; morbid 
 anatomy of, 101. 
 
 Subcutaneous haemorrhage, 75, 78. 
 
 Subvesicular haemorrhage, 77. 
 
 Suffusion of eyes, 60. 
 
 Swr.it, influence of, on distribution, 7. 
 
 Syncope with toxic smallpox, 87, 91, 
 92. 
 
 Syphilis, 125 et seq. ; distribution in 
 the case of, 125, 126 ; papular and 
 pustular rashes of, 126, 127 ; poly- 
 morphic character of lesions of, 51, 
 1 26 ; position in skin of lesions of, 
 31, 127 ; roseola of, 125 ; vesicular 
 rashes of, 12.~>. 
 
 Temperature, see " Pyrexia." 
 Toxaemia, variolous, symptoms of, 3, 
 53 ; temperature with, 59. 
 
 Toxaemic and suppurative fevers, 
 inter-relation of, 63. 
 
 ha?morrhage, 75. 
 
 petechial or purpuric rash, 67, 
 
 97 ; diagnosis of, 69 ; diag- 
 nostic value of, in cases of 
 toxic smallpox, 102 ; dis- 
 tinction of, from rash of scarlet 
 fever, 69, 99, 108 ; effect of, 
 on incidence of focal rash, 
 69. 
 
 rashes, definition, 2 ; variolous, 
 
 3, 66 et seq. 
 
 rose-rashes, 70 ; distinction 
 
 from rash of measles, 71, 107, 
 from rash of scarlet fever, 71, 
 108, from rubella, 108, from 
 toxic erythema, 99. 
 Toxic erythema, 98 ; distinction from 
 measles, 99, 107, from scarlet 
 fever, 99, 108, from toxaemic 
 rose-rash, 99. 
 
 rashes, 97. 
 
 smallpox, albuminuria with, 
 
 91 ; cases illustrative of, 80 ; 
 character of focal rash of, 41, 
 77, 95 ; constitutional symp- 
 toms of, 85 ; date of death 
 from, 94 ; definition of, 73 ; 
 diagnosis of, 101 ; distinction 
 from enteric fever, 109, from 
 measles, 99, 107, from scarlet 
 fever, 99, 108, from typhus, 
 109 ; duration and course of, 
 93 ; enlargement of the liver 
 with, 91, 103; evolution of 
 eruption delayed with, 93 ; 
 facies of, 86 ; fcetor with, 90 ; 
 haemorrhagic symptoms of, 76, 
 96; heart-failure with, 87, 
 91 ; in the case of a new-born 
 infant, 84, 97 ; mental symp- 
 toms of, 87 ; morbid anatomy 
 of, 100 ; oedema of the lungs 
 with, 79, 91 ; outcrop post- 
 poned with, 94 ; pyrexia 
 with, 87 ; recovery from, 92 ; 
 termination of, 91 ; with 
 modified focal rash, 93.
 
 154 
 
 INDEX 
 
 Trunk and limbs, distribution on, 15, 
 
 18, 19 ; with chickenpox, 121. 
 Tuberculosis, acute, 132. 
 Typhus, 109. 
 
 Ulcerative endocarditis, 103, 132. 
 Umbilication of vesicle, 32 ; spurious, 
 
 32 ; with chickenpox, 120. 
 Underclothing, irritative effect of, 7. 
 Uraemia, 132. 
 Urinary organs, morbid anatomy of, 
 
 100. 
 Urticaria, acute, 113 ; with erythema 
 
 multiforme, 112. 
 Uterine haemorrhage, 78. 
 
 Vaccination after exposure to infec- 
 tion, 144 ; after the onset, 145 ; as 
 a factor in diagnosis, 141 et seq. ; 
 effect of, in modifying the eruption, ' 
 45, 144 ; evidence of successful, 142 ; 
 influence of, on numerical severity 
 
 of attack, 44 ; provocative of 
 irritation-patch, 6, 128, 145. 
 
 Vaccinia, 128 et seq. ; auto-inoculation 
 of, 129 ; distribution in the case of, 
 130 ; generalised, 129 ; resembling 
 modified smallpox, 130 ; super- 
 numerary pustules of, 128. 
 
 Varicella, see " Chickenpox." 
 
 Variola haemorrhagica pustulosa, 85, 
 footnote. 
 
 sine eruptione, 63. 
 
 Vascular system, morbid anatomy of, 
 101. 
 
 Vesicles, formation of, 26 ; loculation 
 of, 28 ; of chickenpox, 31, 53, 119 ; 
 size of, 27 ; umbilication of, 32. 
 
 Virulence of strain, variation of, 49. 
 
 Vomiting, with acute febrile erythema, 
 114; with the toxaemia, 60; with 
 toxic smallpox, 100. 
 
 Washbourne on the pathology of 
 smallpox, 8. 
 
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 1910 
 
 Ricketts, Thomas F 
 
 The diagnosis of smallpox 
 
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