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EPIDEMICS 
 
 EXAMINED AND EXPLAINED 
 
 OE, 
 
 LIVING GERMS 
 
 PBOVED BT ANALOGY TO BE 
 
 A SOURCE OF DISEASE. 
 
 BY 
 
 JOHN GROVE, M.R.C.S.L. 
 
 AUTHOR OF " SULPHUR AS A REMEDY IN EPIDEMIC CHOLERA. 
 
 LONDON: 
 
 JAMES RIDGWAY, PICCADILLY. 
 
 MDCCCL. 
 
 
The tendencies of the mind, the turn of thought of whole ages, 
 have frequently depended on prevailing diseases ; for nothing 
 exercises a more potent influence over man, either in disposing 
 him to calmness and submission, or in kindling in him the 
 wildest passions, than the proximity of inevitable and universal 
 danger." — Hecker''s Epidemics of the Middle Ages. 
 
 The grand field of investigation lies immediately before us ; we 
 are trampling every hour upon things which to the ignorant 
 seem nothing but dirt, but to the curious are precious as gold." 
 Servell on the Cultivation of the Intellect. 
 
1^ - wriit^r^ I 
 
 Pu.bl.c 
 
 UeaHk 
 
 / 
 
 TO 
 
 BENJAMIN GUY BABINGTON, F.R.S., M.D., 
 
 PHYSICIAN TO GUY'S HOSPITAL, 
 
 AND 
 
 PRESIDENT OF THE EPIDEMIOLOGICAL SOCIETY, 
 
 ETC. ETC. 
 
 THESE PAGES ARE, BY HIS KIND PERMISSION, 
 
 I^iclpectfuUp IBetltcatcK, 
 
 B\ HIS OBLIGED AND FAITHFUL SERVANT, 
 
 THE AUTHOE. 
 
PREFACE, 
 
 The following pages have been written 
 with a view to render some aid in establishing 
 a sound and firm basis for future research, on 
 that absorbing topic, the Causes and Nature 
 of Epidemic Diseases. 
 
 The amount of information already pub- 
 lished on Fevers, on the Exanthemata, and 
 on the Plague, is truly astonishing, and the 
 more so when it is considered, that at pre- 
 sent no rational account or explanation is 
 given of the causes of these affections. 
 
 It appears to me but reasonable to sup- 
 pose tliat as every thing on this earth has 
 been created on a wise and unerring prin- 
 ciple. Epidemic and Infectious Diseases 
 are only indicative of some serious errors in 
 our social arrangements and habits. The 
 dangers and misery brought upon us by 
 disease, may, as shewn by Dr. Spurzheim 
 and Mr. Combe, be warnings against the 
 infringement of the natural laws. 
 
 Indeed, what is more rational than to sup- 
 pose that the Seeds of Disease are coeval 
 with the fall of man. His first disobedience 
 
VI 
 
 brought death : — that his subsequent errors 
 should hasten its approaches is not to be 
 marvelled at. The undetected murderer, 
 though he may escape the punishment 
 human justice would inflict upon him for 
 his delinquency, suffers a penalty in the tor- 
 tures of conscience, infinitely more horrify- 
 ing than the most ignominious death. The 
 law of nature is triumphant. 
 
 No less certain, though after a different 
 manner, are the consequences of minor forms 
 of disobedience. It is so ordained, that 
 certain diseases shall arise, under peculiar 
 conditions, which may have been brought 
 about by a train of causes, easily imagined, 
 and difficult to be explained, but all having 
 their origin in the vices and errors of man in 
 his moral and social relations. 
 
 If man neglects the cultivation of the 
 ground ; with rank vegetation, the germs of 
 fever will invisibly grow and multiply; if he 
 harbours that which is rotten and corrupt, 
 he is himself consumed by those agents de- 
 stined to remove the rottenness and cor- 
 ruption ; it is a part of the law of nature that 
 there should be active and energetic agents 
 for this purpose. The seeds of disease, like 
 the seeds of plants, may be shewn to havo 
 
Vll 
 
 their indigenous localities ; like them they 
 may be spread and multiplied ; like them 
 they may lie dormant, and after awhile 
 spring as it were into active existence ; like 
 them, when the soil and other conditions 
 favour, they are ever ready to make their 
 appearance. And this is the law, the germs 
 of all disease exist, and have existed. De- 
 spise the dictates of nature, be careless of 
 yourself and those around you, neglect to 
 use the means which a noble intelligence 
 has placed at your command, and above all, 
 transgress the laws of God, then will dis- 
 ease pursue and attend you, as the con- 
 science of the murderer pursues and attends 
 him until he is finally cut off. 
 
 His wants and necessities, his sufferings 
 and privations, are the basis of the intellec- 
 tual progress of man. The wonders of 
 Omnipotence are revealed through the whirl- 
 wind, the storm, the pestilence, and the 
 famine. 
 
 The constructive and perceptive faculties 
 of man have been developed by the neces- 
 sity of protecting himself from injury by 
 winds and rains ; his intellectual faculties 
 have been cultivated, by the sufferings of 
 disease having led him to the study of 
 
r 
 
 vin 
 
 organization and life, to discover the cause, 
 — and to chemistry, and other sciences for 
 the cure of his ailments. 
 
 Famine and distress have aroused his 
 emotions, and softened down his asperities, 
 so that what appears at first to be the inflic- 
 tion of a Curse without Pity, is in reality a 
 Judgment with Mercy. 
 
 It occurred to me, that on the formation 
 of the Epidemiological Society, the first 
 question for consideration should be. What 
 is the nature of those agents, which induce 
 Epidemic Diseases? are they composed of 
 animate or inanimate matter ? In other 
 words, do the manifestations of these dis- 
 eases exhibit the operations of living or of 
 chemical forces. 
 
 Having, in my study, dwelt on the sub^ 
 ject with an earnest desire to find the truth, 
 I put the suggestion, with my ideas, before 
 the public to reject or receive them. If they 
 be rejected, I can but think a full discussion 
 of the enquiry will lead to the most impor- 
 tant results. If they be received with favour, 
 I doubt not others, with more ability, will 
 take up the strain and resolve the discords 
 
 into harmony* 
 
 %/ 
 
 J. G. 
 
 Wandsworth^ September, 1850, 
 
CONTENTS, 
 
 PAGB 
 
 iNTRODrCTION^ . . . ... . .1 
 
 CHAPTER I. 
 
 TS IT PROBABLE THAT EPIDEMIC, ENDEMIC, AND IN- 
 FECTIOUS DISEASES, DEPEND UPON VITAL GEEMS 
 FOll TUEIB MANIFESTATIONS ? . . . .11 
 
 CHAPTEE II. 
 
 THE NUMBER AND YALUE OP FACTS TO SUPPORT 
 THE PROPOSITION. 
 
 Section I.— On Reproduction 22 
 
 Section II. — Historical Notice of Epidemic Diseases . 34 
 
 Section HI. — The Dispersion of Plants and Diseases . . 64 
 Section IV. — The Relation between Epidemic and Endemic 
 
 Diseases , : 96 
 
 CHAPTER III. 
 
 THE REASONABLENESS OP THE APPLICATION OF 
 THE FACTS TO THE INFERENCE. 
 
 Section I. — The Chemical Theory of Epidemics untenable . 108 
 Section II. — The Animalcular Theory of Epidemics un- 
 tenable 128 
 
 Section III.— Sketch of the Physiology and Pathology of 
 
 Plants and Animals 138 
 
 CHAPTER lY. 
 
 RESULTS IN PROOF OF THE TENABLENESS OF THE 
 PROPOSITION. 
 
 Section I. — Observations on some of the Laws of Epidemic 
 
 Diseases 155 
 
 Section II. — What is the nature of those Poisons which most 
 
 resemble the Morbid Poisons in their effects on the body ? 166 
 
 Section HI.— What results do we obtain from the effects of 
 
 remedial agents, in proof of the hypothesis ? . . . 176 
 
 Conclusion 189 
 
INTRODUCTION. 
 
 It is one thing; for a man to convince 
 himself, but a very different thing to be able 
 to convince others. 
 
 I am not now speaking of a conviction 
 arising from the impression made by a few 
 startling facts, nor of one forced on the 
 mind by early prejudices, or by the dogmas 
 of the schools, but of a conviction arising from 
 careful enquiry. 
 
 In the course of that enquiry, the col- 
 lector of facts, sees their relations to the 
 idea in his mind, in a multiplicity of ways, 
 from their remaining, each, as one succeeds 
 the other, an appreciable time on the sen- 
 sorium, and undergoing a certain process of 
 comparison and relation, with all other facts 
 and ideas which have been previously stored 
 up. As the materials for an edifice which 
 have been shaped and prepared in accord- 
 ance with the completion of the design, so 
 do the facts and ideas which are accumulated 
 
 B 
 
in the mind, become shaped and prepared 
 for the elimination of a truth. The ultimate 
 design of the architect can no more be con- 
 ceived bv the examination of the framework 
 of a window, or the capital of a column, than 
 the whole truth of a proposition by the ex- 
 amination of separate facts ; the whole must 
 be conceived and all the relations of all the 
 parts thoroughly understood, before the ar- 
 chitect can be comprehended or the harmony 
 of his design appreciated. 
 
 The process of thought in the minds of 
 the architect, and in the framer of a proposi- 
 tion, is never exactly the same as in those 
 who contemplate and examine their com- 
 pleted works. Much maybe done, however, 
 by both to aid others in comprehending them. 
 The more accurately they keep in view the 
 course their minds have taken, the more 
 readily will their descriptions be understood. 
 
 To simplify the elements of our knowledge 
 is to give others a ready access to our 
 thoughts. 
 
 To arrange the course of our ideas in har- 
 mony with the elements^ of our knowledge 
 should be the end of all writing, as it is the 
 only means of multiplying knowledge. 
 
It is not the mere accumulation of facts 
 which constitutes science, any more than a 
 collection of building materials constitutes a 
 house, it is the arrangement and adaptation 
 of the means to the end by which the house 
 becomes built and science cultivated. 
 
 These reflections have been suggested by 
 the circumstance that for the last 3000 years 
 and upwards, Pestilences have at certain 
 intervals done their work of destruction, and 
 opened the springs of misery to untold mil- 
 lions, and yet I see not that we are much 
 further advanced as to the knowledge of the 
 cause of these inflictions than the Jews in 
 the time of Moses. In the Levitical law, as 
 I shall have occasion more particularly to 
 shew hereafter, were directions specially 
 given in reference to the plague of leprosy ; 
 what means should be adopted for the cure 
 of the disease, and for preventing its exten- 
 sion, and moreover pointing very signifi- 
 cantly to certain facts having connexion 
 with the cause of the affection. Since that 
 time historians generally, and medical 
 writers in particular, have diligently re- 
 corded their observations and accumulated 
 facts, on tlie various desohiting phigues which 
 
 B 2 
 
 l^ 
 
L 
 r 
 
 have afflicted mankind. Some of these men 
 have grappled with the whole subject, and 
 endeavoured to shew the presumed relation 
 of the supposed causes in all their intrica- 
 cies, but it is hardly necessary to say that 
 all have signally failed in their attempts to 
 furnish us with any practical information. 
 
 Satisfied in my own mind that the whole 
 subject is beyond the labour of one man, 
 and impressed with the belief that the basis 
 of the enquiry is in anything but a satisfac- 
 tory state, I have applied myself entirely 
 to the study of the groundwork only, as 
 the primary proceeding for a solid super- 
 structure. 
 
 The days are past, when imaginary spirits, 
 ethers, and astronomical phenomena, were 
 believed to have any essential influence over 
 our destinies in a physical point of view; we 
 have therefore to deal with matter in some 
 form or other. 
 
 The question, therefore, which I have 
 proposed for enquiry, is, whether the mat- 
 ter which causes epidemic and endemic 
 diseases, exhibits the properties of inorganic 
 or organized matter. 
 
 The properties and qualities of organized 
 
bodies, as well as those of inorganic matter, 
 need but be stated, and in some instances / 
 we may picture to ourselves the object, 
 without having seen it, and not be very far 
 from a true conception. But for this pur- 
 pose a clear and definite idea must be pre- 
 viously formed, and have taken possession 
 of the mind, of the great general divisions 
 of objects in the material world. 
 
 Having made these preliminary remarks, 
 I have suggested a certain mode of proce- 
 dure in making enquiries of this kind, not 
 perhaps in strict accordance with logical 
 systems, but on the principle of nature's 
 operations in our own minds, which appears 
 to me, when reduced to a systematic and 
 simple form, to be sufficiently clear and 
 strict for synthetical application, and so 
 concise as to be usefully and practicably 
 applied. 
 
 In endeavouring to establish a theory for 
 the explanation of extraordinary phenomena, 
 there are certain rules which should guide 
 us in the thorny and treacherous path of 
 speculation. But these rules readily flow 
 from the train of thought, and if we examine 
 our own minds during their operations, we 
 
6 
 
 shall find that the following is the course of 
 our instinctive reflections. It is a course 
 we adopt as the test of theories when formed, 
 and is a guide in all cases for their construc- 
 tion. 
 
 We first commence with an idea, which 
 exists in our minds in the form of a proposi- 
 tion : then the following rules naturally 
 suggest themselves : — 
 
 1. The probability of the value of our 
 proposition from inference. 
 
 2. The number and value of facts to sup- 
 port the proposition. 
 
 3. The reasonableness of the application 
 of the facts to the inference. 
 
 4. What amount of information in the 
 form of results can be produced in proof of 
 the tenableness of the proposition.* 
 
 In illustration of the value of these rules 
 the history of Dr. Jenner's discovery affords 
 an appropriate example. To use the words 
 of Dr. Gregory, " he appears very early in 
 
 * " It matters little how vague and false hypotheses may 
 appear at first : experiment will gradually reduce and 
 correct them, and all that is required, is industry to elabo- 
 rate the proof, and impartiality to secure it from distor- 
 tion." — Sewell " On the Cultivation of the Intellect."— 
 
life to have had his attention fixed by a 
 popular notion among the peasantry of 
 Gloucestershire, of the existence of an affec- 
 tion in the cow, supposed to afford security 
 against the Small Pox ; but he was not 
 successful in convincing his professional 
 brethren of the importance of the idea." 
 
 The popular notion of the peasantry origin- 
 ated the idea in Jenner s mind, and it became 
 fixed there as a proposition. 
 
 1. He commenced his enquiry by observ- 
 ing that the hands of milkers on the dairy 
 farms were subject to an eruption, and he 
 inferred that the notion of the peasantry bore 
 the stamp of probability, which strengthened 
 the idea in his mind and gave force to the 
 proposition. 
 
 2. His next step was to accumulate facts ; 
 he found on enquiry that the persons 
 engaged on these farms in milking, possessed 
 an immunity from Small Pox to an extent 
 sufficient to strengthen the value of his pro- 
 position. 
 
 3. The reasonableness of the application 
 of the facts to the inference is clear from the 
 coincidence that the eruption on the hands 
 of the dairy people bore a striking resem- 
 
8 
 
 blance to the Small Pox, and as this disease 
 does not usually occur twice in the same 
 individual, the inference was most reason- 
 able that this eruption protected the people 
 from Small Pox. 
 
 4. We have but to take the almost uni- 
 versal adoption of vaccination, and its 
 acknowledged prophylactic powers against 
 the propagation of Small Pox to shew the 
 application of our fourth rule.* 
 
 Between the conception of the idea and 
 the accomplishment of Jenner's designs, 
 vaccination seems to have undergone an 
 incubation of nearly twenty years. During 
 that period, with an energy and perseverance 
 only to be obtained by confidence, did this 
 great man brood over and elaborate his 
 idea ; and well might the 14th day of May, 
 
 * It is stated by Mr. Crosse, of Norwicli, that vaccina- 
 tion was adopted in Denmark, and made compulsory in 
 1800. After the year 1808 Small Pox no longer existed 
 there, and was a thing totally unknown ; whereas during 
 the twelve years preceding the introduction of the preven- 
 tive disease, 5,500 persons died of the Small Pox in 
 Copenhagen alone. — Dr. Watsons Lectures. 
 
 Dr. Blick, an intelhgent Danish physician, corroborated 
 the above statement to Dr. Watson himself in the year 
 1838. 
 
9 
 
 1796, be styled the birth day of vaccination, 
 for on that day was a child first inoculated 
 from the hands of a milker. 
 
 In adopting the above method I have 
 endeavoured to bear in mind M. Quetelet's 
 observations on the requirements necessary 
 for medical authorship; he says, "All reason- 
 able men will, I think, agree on this point, 
 that we must inform ourselves by observa- 
 tion, collect well-recorded facts, render them 
 rigorously comparable, before seeking to 
 discuss them with a view of declaring their 
 relations, and methodically proceeding to 
 the appreciation of causes." 
 
CHAPTEE I. 
 
 IS IT PROBABLE THAT EPIDEMIC^ ENDEMIC^ AND 
 INFECTIOUS DISEASES^ DEPEND UPON VITAL 
 GERMS FOR THEIR MANIFESTATIONS? 
 
 It is^ I believe^ almost universally considered 
 that Epidemic^ Endemic, and Infectious diseases, 
 originate from some imaginary poisons of a spe- 
 cific nature^ each disease having* its own peculiar J 
 poison. That this conception should have taken 
 possession of the minds of men, is most natural 
 from the symptoms which characterize these dis- 
 eases, but when we come to enquire into the nature , 
 of these ag-ents, or supposed poisons, we are at once / 
 struck with the idea that they exhibit one pecu- 
 Harity which separates them in a marked manner, \ 
 fi*om those poisons with which we are familiar ; for 
 the poisons of Small Pox, Measles, Scarlet Fever, 
 Hooping Cough, Fever, &c. possess the power of 
 multiplication, or spontaneous increase, a property 
 which attaches only to the organic kingdom, and is 
 never known in the inorganic kingdom. The source 
 of most of the poisons is to be found among mineral 
 or vegetable products. A mineral in combination 
 with an acid or oxygen may become a poison, and 
 
12 
 
 riitrog-eii in various combinations Avitli oxyg-en^ 
 
 hydrogen^ and carbon^ or with carbon alone^ may 
 
 become a poison ; these combinations are^ however^ 
 
 in most instances the products of veg-etable life, 
 
 ^ others ag-ain are obtained from the animal king-dom, 
 
 such as the poison of the serpent, &c. but in all of 
 
 \ these instances, there is not one in which the power 
 
 / of self-multiplication is to be found. 
 
 We are, therefore, constrained to admit that this 
 feature, which disting-uishes poisons, is one well 
 worthy attentive consideration. The varieties of 
 { poisons may be classified into those which act 
 1 topically as escharotic poisons, those which act 
 ; chemically on the blood, and those whose effects are 
 ^ manifested in inducing* a speedy annihilation of 
 organic or vital action, as in the case of hydro- 
 cyanic acid, which is supposed specifically to affect 
 the nervous centres from which orig-inate the vital 
 manifestations. It is rather remarkable that the 
 vital poisons (as I will call them for distinction), 
 seem to have their appropriate locality in the blood, 
 they do not primarily affect one org-an more than 
 another, all the effects we witness resulting- from 
 them are to be traced prog-ressively from the blood 
 to other parts of the body. When a person is 
 inoculated with small pox, a very minute portion 
 (indeed it is impossible to say how minute it may 
 be) is sufficient, when absorbed, to excite a certain 
 train of symptoms, all due to absorption of the 
 materies of the disease, and the process by which 
 
 \ 
 
1.3 
 
 that materies arrives at maturity^ is that knowu in 
 the veg-etable world as the fructification -, this pro- 
 cess of fructification is a process of development and 
 increase. 
 
 I here may repeat that among- all the poisons ^ 
 known^ constituted as they are of various combina- 
 tions of elementary matter^ they are without 
 exception destitute of the power of development or 
 increase. Now^ it is pretty accurately known what 
 amount of these poisons is necessary to produce 
 their effects on the living body ; we can say how 
 many drops are sufficient of h3^drocyanic acid of 
 Scheeles strength^ to destroy a man instantaneously. 
 Ag*ain^ how man}^ g-rains of arsenious acid are 
 sufficient to induce such an inflammatory condition 
 of the stomach and intestine as will end in death^ 
 and how many g-rains of morphia^ will bring* about 
 a fatal coma^— but who shall say the amount of the ^ 
 vital poisons necessary to produce their results ? It / 
 far exceeds the limit of conjecture^ to what extent > 
 the dilution of miasmatic or contagious matter may 
 be carried^ and the poison yet be capable of com- \ 
 mitting- in a short time the most frig-htful ravag-es. 
 
 We may fairly then infer^ that if a quantity of 
 matter inappreciable in amount be sufficient to ex- 
 hibit the characters of g-rowth and increase^ that it 
 is endowed with the properties of vitality. That 
 the poisons of scarlet fever^ of measles^ and of small- 
 pox have this power of g-rowth and increase, is as 
 much a matter of universal belief as that '^ the sun 
 
14 
 
 will rise and set to-morrow^ and that all living- being-s 
 will die/' 
 
 This power of individual increase^ or reproduction^ 
 
 is the very summit of vital manifestation \ indeed 
 
 Coleridg-e^ in his Theory of Life^ (in which he says^ 
 
 ^^ I define life as the 'principle of individuation j or 
 
 / the power which unites a given all into a whole that 
 
 A is presupposed by all its parts/') places reproduction 
 
 in the first rank^ and expresses his hypothesis thus : 
 
 '^ the constituent forces of life in the human living- 
 
 I body are^ first; the power of leng-th or reproduction • 
 
 I 2nd; the power of surface, or irritability ] 3rd; the 
 
 I power of depth; or sensibility — life itself is neither 
 
 V of these separately; but the copula of all three/' 
 
 Extensive research is not required to shew that 
 many thinking* men believe in the existence of living- 
 org-anic being-S; as the elements of contag-ious and 
 epidemic diseases; the idea indeed seems to flow 
 spontaneously in that direction. Whenever thoug-ht; 
 ( and enduring" contemplation; have been concentrated 
 on the subject; the result appears to have been the 
 samC; a firm conviction in each individual mind that 
 a vital force must be" in operation ; or as Schleg-el 
 would define it; ^^a living* reproductive power; 
 capable of and desig-ned to develope and propag-ate 
 itself." — '^ Its Maker orig-inally fixed and assig-ned 
 to it the end towards which all its efforts were 
 ultimately to be directed." 
 
 Referring- further to being-s having* the property 
 of reproduction and propag-atioU; he sayS; (using- 
 
15 
 
 the word nature here evidently as the vital principle 
 for want of a better term^) ^^ Nature indeed is not 
 free like man^ but still is not a piece of dead clock- 
 work. There is life in it J' — ^^ Thus we know that 
 even plants sleep^ and that they too as much as 
 animals^ though after a different sort^ have a true 
 impreg-nation and propagation/' 
 
 When Schlegel wrote this^ how little could he 
 have imagined the intricacy of this proceeding 
 among the lower forms of vegetation. It has been 
 shewn by Suminski^ and verified by many others, 
 that the mode of impregnation, and the period at 
 which it occurs in the ferns, do not at all correspond 
 to the general notion on this subject. He has dis- 
 covered in the early development of the frond of 
 ferns certain cells, w hich he denominates antheridia, 
 or sperm cells; these contain in their cavity a 
 number of subordinate cells, each containing a sper- 
 matazoon. At a certain period of the progTess of 
 the frond, the parent cells become ruptured and 
 liberate the spermatoza, these move about in a 
 mucilaginous fluid, which bedews the inferior surface 
 of the frond, and become the means of impregnating 
 the germ cells, or pistillidia, with which they readily 
 come in contact. Thus the process of impregnation 
 in these plants occurs during the germination, or 
 what corresponds to the period of germination in 
 the seeds of exogenous and endogenous plants. 
 I have referred to the discovery of Suminski in 
 
 ^ 
 
\ 
 
 \ 
 
 16 
 
 this place to recal to the mind the great and incom- 
 prehensible wonders of creation^ for who could con- 
 ceive it possible or feasible that even for the 
 impreg-nation of an inferior vegetable^ animal life 
 should form an indispensable and essential appurte- 
 nant of the process. Truly ma}^ we say Avith 
 Coleridge^ of plants and insects^ "so reciprocally 
 inter-dependent and necessary are they to each 
 other^ that we can almost as little think of veg-eta- 
 tion without insects^ as of insects without veg^eta- 
 tion/' 
 
 I will make but two more quotations on the 
 supposed vital character of the g-erms of disease. 
 '' That the air and atmosphere of our g'lobe is in 
 the hig-hest deg-ree full of life^ I may^ I think^ take 
 here for g-ranted^ and g-enerally admitted. It is^ 
 however^ of a mixed kind and quality^ combining- 
 the refreshing* breath of spring- with the parching- 
 simooms of the desert^ and where the healthy odours 
 fluctuate in chaotic strug-g'le with the most deadly 
 vapours. What else in g-eneral is the widespread 
 and spreading pestilence^ but a living- propagation of 
 foulness^ corruption^ and death? Are not many 
 poisons^ esj^ecially animal poisons^ in a true sense^ 
 liviiig forces T^ — Schlegel.* 
 
 It were useless to multiply quotations to shew 
 
 * Philosophy of Life, Lecture 6, translated by the Rev. 
 A. J. W. Morrison, MA. 
 
L^ 
 
 17 
 
 that tlie opinions here entertained are matters of 
 g^eneral hehef among* thinking- men.- I will at 
 once then conclude with an observation of Dr. 
 C. J. B. Williams : he puts the question^ ^^ Does 
 the matter of contao*ion consist of veo-etable seeds ? 
 Are infectious diseases the results of the opera- 
 tions and invasions of living- parasites^ disturbing- 
 in sundry Avays the structures and functions of 
 the body^ each after its own kind, until the vital 
 powers either fail or succeed in expelling- the 
 invading- tribes from the S3^stem ?'' 
 
 And this expression, the seeds, is an universal 
 expression, it is a ^^ Household Word" in connexion 
 with disease. That it has obtained this position in 
 the popular vocabulary is alone a proof of the appli- 
 cabiUty of the term to the thing- intended to be 
 
 * The following I quote from Dr. Fuller on Small Pox 
 and Measles : — 
 
 ''To this purpose some (and particularly Kircherus) 
 are of opinion that animalcules have been the causes of 
 malignant and pestilential fevers in epidemic times, which 
 differ in essence and symptoms, according to the nature 
 and venoms of those creatures. /^-^"^ 
 
 " Thus the atmosphere and air is filled both from above 
 and beneath with innumerable miUions of millions of 
 species or corpuscles, aporrhoeas, steams, vapours, fumes, 
 dust, little insects, &c. all which make it such a wonderful 
 chaotic compost of things that contains the seeds of good 
 and evil to man as surpasseth the understanding (as I 
 suppose) of even the highest order of archangels." 
 
 C 
 
18 
 
 signified. Popular notions^ as we have seen in the 
 case of Jemima's discovery^ are not to he unheeded. 
 An instance occurs to me^ it was a popular belief, 
 that in acne punctata^ the matter of a sebaceous 
 ^ follicle^ was itself^ when pressed out^ a worm^ the 
 
 dark portion which results from the accumulation of 
 dust upon the matter at the mouth of the follicle 
 was supposed to be the head of the mag-g-ot^ as it 
 was called; subsequent observation^ however^ has 
 proved that thoug-h this matter is not a worm^ it 
 contains an animal within its substance^ the A cams 
 folliculorum. 
 
 The popular notions found among* savage tribes 
 
 as to the efficacy of certain remedies in the cure of 
 
 disease have been the means of furnishing* us with 
 
 some of our most valuable medicines^ indeed it is 
 
 \ 1 almost impossible to say whether orig-inally man did 
 
 not derive his remedies from the herbs and trees by 
 
 j an instinctive faculty impelling* him^ as it does the 
 
 I animals when in a state of liberty and with freedom 
 
 of rang'e^ to seek certain plants as they avoid others. 
 
 It is well known that animals when indisposed 
 
 'y will find out some^ spot as if almost led to it by a 
 
 visionary g-uide where the ^^ healing* plant'' is to be 
 
 discovered. I am told that sheep have this faculty^ 
 
 and that they will^ when affected with the rot^ feed 
 
 upon some plant when they can discover it^ which 
 
 eradicates the disease. 
 
 Almost every one is familiar with the fact that 
 cats and dogs will crop herbage and eat it ] I have 
 
 r 
 
 K 
 
 \ 
 
 \ 
 
19 
 
 seen them frequently leave the house and proceed to 
 the gi'ass in the most business-like manner, partake 
 of some quantity, and quietly return. 
 
 A close observer of diseased animals mio-ht obtain 
 some useful information by noticing* the plants 
 cropped by them while in that condition. The ^ 
 
 observations should be made in a variety of districts 
 in consequence of the uncertain distribution of some -^ 
 even of the most commonly scattered plants 5 in 
 one year they may be abundant, but in another 
 they may be almost entirely absent from the same 
 spot.* 
 
 Were it only on the fact of reproduction, I would I 
 be contented to take my stand that the force of life 
 is the indwelling- power of pestilential matter. Re- 
 production is a law of nature, and the law of nature [^ 
 is the law of God. And where do we find He prevari- 
 cates with us ? The more we study His laws the more 
 harmony and perfection we find ; what is seeming- 
 confusion in the ig-norance of to-day, is order in the 
 knowledge of to-morrow. If any one ig-norant of ; 
 the law which reg-ulates the diffusion of g'ases were 
 
 * I learn from an undoubted authority that the cow 
 when '' slack of health" eats with avidity the '' field 
 parsley ;" the sheep under similar circumstances seeks the ^ 
 
 ivy, and the goat the plantain. 
 
 From an equally good source I have the following : that 
 rabbits and hares, wlien they are what is commonly called 
 pot-gutted, seek tlic green broom, though at a (hstancc of 
 twenty miles. 
 
 c 2 
 
20 
 
 told that a heavier g*as would ascend contrary to its 
 specific gravity throug'li the septum in a vessel 
 containing" a lig-hter g-as above the heavier^ he would 
 naturally doubt your assertion^ and say^ ''- that is 
 contrary to the law of g-ravity /' but explain to him 
 the principle by which this comes about^ and the 
 objects of the law \ the order and beauty of the desig-n 
 become manifest. But this is no equivocation^ it is 
 evidence there^ that subordinate laws exist and 
 nothing" more. It has never been found that men 
 ha,ve g-athered ^^g-rapes of thorns and figs of thistles/' 
 nor has it ever been discovered that inanimate 
 matter multiplies itself. The seed of disease ^^is 
 within itself/' multiplying- and propag'ating* itself; 
 whether it formed a part of creation at the beg-in- 
 nin^ or not^ is rather a question to be solved by 
 f divines than physicians. When we know^ however^ 
 the latency of seeds and even of entire plants^ and 
 that they may be dried and remain so for years yet 
 being- broug-ht ag-ain into conditions adapted to their 
 active existence^ they^ as it were^ revive from their 
 sleepy and renew ag-ain their reproductive properties: 
 can we wonder if, in the g-reat scheme of nature^ 
 existences new to mankind should make theii* ap- 
 pearance ? When the New Zealander saw the 
 surface of his g-round producing- to him unknown 
 plants^ and the skins of his children g-enerating 
 peculiar eruptions^ and each propagating- its kind^ 
 would he look^ think you^ to the wood or the stones^ 
 the air or the water^ — for the solution of the 
 
21 
 
 mystery ? No, he would naturally say these people 
 broug-ht the seeds with them. From the property 
 of reproduction possessed by these forms of matter, 
 we infer the value of the proposition. 
 
 • 
 
CHAPTER II. 
 
 THE NUMBER AND VALUE OF FACTS TO SUPI'ORT 
 THE PROPOSITION. 
 
 SECTION I. 
 
 ON REPRODUCTION. 
 
 It is inferred that the proposition^ ^' the matter 
 wfvich operates in the production of Epidemic^ En- 
 demic, and Infectious Diseases y possesses the property 
 of vitality y^ we proceed now to the enumeration of 
 those facts which further elucidate this subject. 
 
 The facts must necessarily be such as illustrate 
 the identity of properties in the imaginary germs^ 
 that are known to exist in demonstrable germs : 
 we take therefore the law of reproduction to be to 
 life^ what the law of attraction is to gravitation.* 
 
 * " My settled opinion is, that in regard every effect is 
 necessarily such as its cause ; it must needs be that every 
 sort of venomous fevers is produced by its proper and pe- 
 culiar species of virus. 
 
 ^^And that the manner and symptoms of every such 
 fever is not so much from the particular constitution of the 
 sick; as from the different nature and genius of their 
 specific venom which caused them. 
 
 " And I conceive that venomous febrile matters differ 
 not in degree of intenseness only, but in essence and toto 
 genere also; and that venomous fevers are for the most 
 part contagious. ^^ — Thomas Fuller, M. D. 1730. 
 
But further; do those matters which eng-ender 
 disease furnish to our minds the properties in- 
 separable from life in the abstract ? Thoug'h the 
 faculty of reproduction is essentially an evidence 
 that the thing- which reproduces its kind must be a 
 living body^ yet it is only a property or power of 
 living" being's and is not itself life, it therefore is 
 necessary to establish the fact that the materies 
 inorhi not only has the power of reproduction, but 
 also those properties which in the abstract will prove 
 as far as demonstration can g'o, that it has 
 essential properties common to all living* bodies. 
 
 I must ag-ain quote from Coleridg-e, he sa; 
 '^ By life I every where mean the true idea of life, 
 or that most g-eneral form under which life mani- 
 fests itself to us, which includes all its other forms. 
 This I have stated to be the tendency to individuation 
 and the degTees or intensities of life, to consist in 
 the progressive realization of this tendency. The 
 
 " Another important class of organic poisons are those 
 which when introduced in almost inappreciable quantities 
 into the system, seem to increase in quantity ; and which 
 when communicated in the same inappreciable quantity 
 from the individual poisoned to one who is healthy, excite 
 the same series of febrile phenomena and local inflamma- 
 tion, and the same increase in the quantity of the poisonous 
 asrent/' — Med, Chir. Review. 
 
 " This unseen influence working in the body, presents 
 very striking analogies to the modes of operation of dif- 
 ferent poisons." — Dr. Ormerod on Continued Fever. 
 
 L^ 
 
24 
 
 power which is acknowledg-ed to exist wherever the 
 realization is found^ must subsist wherever the ten- 
 dency is manifested. The power which comes forth 
 and stirs abroad in the bird^ must be latent in the 
 eg-g-." 
 
 The tendency to individuation cannot be more 
 strong-ly marked than in the simple experiment of 
 vaccination : we insert a small particle of the so- 
 called vaccine l3^mph under the skin^ and by this 
 means we multiply to an enormous extent^ the 
 power which^ in the first instance^ we had in the 
 form of minute corpuscles in a dry and apparently 
 inert state ; nevertheless^ thoug-h in this condition 
 there must have existed the tendency to individua- 
 tion or multiplication of individual existence^ and 
 the g'erms are here to their active existence^ as seen 
 in the development of the vaccine vesicle^ what the 
 eg'g" is to the bird^* as described above ; we may^ 
 therefore^ say that the power which exhibits itself 
 in the production of a vaccine vesicle^ must have 
 been latent in the dried matter. It is the opinion 
 of MuUer that the entire vital principle of the egg 
 
 * I am aware that the vesicle does not here strictly 
 bear the relation to the original germ, supposing one 
 active particle alone to be sufficient for its production, that 
 the egg does to the bird, for in the former case multitudes 
 of active particles may have been generated from one. I 
 have, therefore, merely used this expression to signify an 
 aggregation of vital forces, such as may be imagined to 
 exist in the bird. 
 
25 
 
 resides in the g-erminal disk alone^ and since the 
 external iiifluenccs which act on the germs of the 
 most different org-anic beings are the same^ we 
 must regard the simple germinal disk^ consisting of 
 g-ranular amorphous matter^ as the potential whole 
 of the future animal^ endowed with the essential 
 and specific force or principle of the future being-, 
 and capable of increasing* the very small amount 
 of this specific force and matter, which it already 
 possesses, by the assimilation of new matter. 
 
 After speaking" of inanimate objects, Dr. Car- 
 penter says J ^' and what compared with the perma- 
 nence of these is the duration of any structure 
 subject to the conditions of vitality "l To he horuy 
 to grow, to arrive at maturity, to decline, to die, to 
 decay, is the sum of the history of every being- that 
 lives ; from man, in the pomp of royalty, or the pride 
 of philosophy, to the gay and thoughtless insect that 
 glitters for a few hours in the sunbeam and is seen 
 no more ; from the stately oak, the monarch of the 
 forest through successive centuries, to the humble 
 fungus which shoots forth and withers in a day." 
 
 To be born, signifies the faculty of reproduction 
 existing or having existed in an antecedent being 
 to that one born, and also that itself possesses 
 equally a like power. To be born, is the first ex- 
 pression which must be used in speaking of the 
 faculties or properties of living- beings as independent 
 existences, the annual formation of buds, trees, and 
 shrubs, is a multiplication of the species ; the coral 
 
^ 
 
 20 
 
 and various budding- polypes increase by this pro- 
 cess^ indeed what is the seed of a plant^ or the eg-g* 
 of a bird^ or the ovum of mammalia^ but cast off 
 buds y in all^ the uew being- was orig-inally a portion 
 of its parent^ and if we examine the ovary of the 
 veg-etable^ the bird^ or the mammal, can we find 
 any expression more fitting- to desig-nate the process 
 than that of budding-. To be born then^ is the 
 evidence of an act of one living- being-^ and the com- 
 mencement of a series of vital phenomena in another^ 
 but all these are subsequent to reproduction^ and 
 constitute another chain of vital acts^ all tending* 
 to a similar result^ the multiplication of the 
 species."^ 
 
 Now^ whether we apply the philosophical lan- 
 g'uag-e of Coleridg-e^ or the lang-uag-e of observation 
 of MuUer^ in confirmation of the doctrine here in- 
 culcated^ we arrive at the same point. 
 
 Do we not witness in the newly formed vaccine 
 vesicle^ an increase of the specific force and princi- 
 ple ? We certainly have acquired by the process of 
 vaccination a manifold multiplication of power^ 
 and is there not also assimilation of new matter in 
 
 ^ ^^ At an early period the form of the ovisacs is usually 
 elliptical_, and their size extremely minute^— their long 
 diameter measuring in the ox no more than -^^-^ of an inch, 
 so that a cubic inch would contain nearly two hundred 
 millions of them. They are at this time quite distinct 
 from the stroma of the ovarium ; this forms a cavity in 
 wliich they are loosely embedded." 
 
S7 
 
 which this power resides ? And does not every 
 particle of this new matter contain within itself the 
 same force and principle, as existed in that which 
 generated it? 
 
 " We revert again to potentiated length in the 
 power of mag^netism (reproduction) ; to surface in 
 the power of electricity, and to the synthesis of 
 both or potentiated depth in constructive, that is 
 chemical affinity."* 
 
 Some may be at a loss to. conceive, at first, how 
 irritability may be considered a property of all 
 vegetable matter ; that it does exist in some vege- 
 tables is certain, but that it does exist in all living 
 beings is equally certain ^f the term, however, which 
 would appear more appropriate when that irritability 
 does not exhibit itself in an appreciable form, is 
 impressibility. Irritability, as commonly under- 
 stood, is seen in its highest condition in muscular 
 tissue ; but ^^ the irritable power and an analogon of 
 voluntary motion first dawn on us in the vegetable 
 world in the stamina and anthers at the period of 
 
 * Coleridge, p. 56. 
 
 t "All vegetables/' says Sharon Turner, "from that 
 pettiness which escapes onr natural sight, to that magni- 
 tude which we feel to be gigantic, have these properties in 
 common with all animals —organization ; an interior power 
 of progressive growth, a principle of life, with many pheno- 
 mena that resemble imtability, excitability, and suscepti- 
 bility, and a self- reproductive and multiplying faculty." — 
 Sharon Turnei-^s Sacred Hi&tory. 
 
\ 
 
 28 
 
 impreg-nation."— "The insect world is the exponent 
 of irritabihtj^ as the vegetable is of reproduction/^ 
 
 The property of irritability attains its acme in 
 man^ the most hig-hly org-anized of all being-s ; and 
 its g-radations pass downwards throug-h the whole 
 scale of animate creation ; not so reproduction^ for 
 this faculty observes the very opposite direction^ for 
 in plants a sing-le impreg-nation is sufficient for the 
 evolution of myriads of detached lives. 
 
 Reproduction is a fact^ it is an essential property 
 of life^ and is a reality to us from observation ', but 
 irritability is not so tangible and demonstrable a 
 property. We nevertheless may assume its univer- 
 sality^ from the circumstance that we lose sight of it 
 \ by imperceptible degrees; the irritability of the 
 
 sensitive plant is as much irritability as that of the 
 highly organized muscle ; but because the faculty 
 evades our perception^ " in tapering by degrees^ be- 
 coming beautifully less/' we have no reason for pro- 
 nouncing its total extinction at any one point of the 
 vegetable kingdom^* any more than we should have 
 
 * " Plants highly sensitive to light are those of the legu- 
 minous, or Pea kind. They always close up in the evening 
 and clasp their two upper surfaces together, presenting 
 only their backs to the air. Plants of pinnated leaves, as the 
 Tansy, are more sensible than these to the effects of light. 
 They fold up when light is too strong, as in Robinia ; it 
 produces the same effect as want of light. Its leaves close 
 up, apparently, because they are receiving too much. So 
 thev do if a hot iron be brought near them. They con- 
 
29 
 
 in saying* that we see the end of the earthy when 
 describing- the extent of our vision as we stand on 
 the sea shore. The extreme limit of our vision is 
 the tang-ent of the circle in reference to our visual 
 org-ans , but how many tang*ential points there may 
 be beyond^ it is impossible to say without knowing 
 the dimensions of the circle. 
 
 I think we are now in a condition to assume^ as A 
 far as abstraction will conduct us without proceeding* / 
 to an extreme leng'th, that the materies morhi, ovy 
 as I will now call them for the sake of clearer dis- \ 
 tinction^ semina morbi, possess those properties \ 
 which in the abstract are common to all living* \ 
 being's. 
 
 Another arg*ument strikes me as capable of adding* 
 further streng*th to the proposition. We need but 
 be told that a small piece of iron was placed in a 
 certain position with reg*ard to another piece of iron^ 
 and that the smaller piece moved throug-h a g*iven 
 space and became attached to the larg-er^ to infer 
 that magnetic force was in operation. Supposing 
 this magnet then to be folded in paper^ and that it 
 
 tract as if to avoid the heat. Sensitive plants, and those 
 of tlic Oxalis Lent, are so sensitive that the least motion, 
 even a breath of air, will make them close/^ — Sir J. 
 Smith. 
 
 " The vitahty of plants seems to depend upon the exis- 
 tence of an irritability, which although far inferior to that 
 of animals, is nevertheless of an analogous character.'' — 
 LindLy's Introduction to Botany. 
 
30 
 
 be promiscuously placed near a compass^ the deflec- 
 tion of the needle would indicate that some object in 
 the vicinity was the cause of the deflection ; we may 
 y farther try what positions the needle takes by vary- 
 
 \ ing- the position of the packet^ and thus point out 
 
 which is the north and which the south pole of the 
 screw of paper. If we may consider attraction then 
 to be to gravitation what reproduction is to life^ we 
 do not err in saying in the one instance that there 
 is a living" being*, and in the other there is a mag-net. 
 The nebular theory^ from which some astronomers 
 made the foundation of many speculations, came 
 with so much interest to our minds that the fascina- 
 tion could not be resisted. It was most delightful 
 to revel in the imagination that we possessed a key 
 to the mode of formation of the starry hosts, and 
 when speculation had taken its extreme limits in the 
 ^^ Vestiges of the Natural History of Creation/^ and 
 the nebulse had served as the ground work of a gi- 
 gantic scheme^ Lord Ross's monster telescope swept 
 the heavens of its cobwebs. We can imagine this 
 great promoter of science saying to us, Gentle- 
 men, the clouds which have obscured you, are 
 composed of myriads of stars, and comprise systems 
 as vast and as luminous as our own, had you but 
 power of vision to discern them. A new lig'ht thus 
 appeared to philosophers, and though no great 
 practical results may flow from the discovery, it is 
 instructive from the fact that the imperfectly aided 
 or unaided vision, should not limit legitimate 
 
31 
 
 inference. The nebuloe before Lord lloss's discovery 
 were to the astronomer what the materies of epidemic 
 and infectious disease are to medical men. In the 
 absence however of a giant microscope to reveal 
 such g-reat truths^ we may yet dimly shadow them 
 by the light of our reason. It was predicted in 
 1849 that minute vegetable germs^ in all probability 
 all of the same type^ were the agents producing 
 epidemic and infectious disease. In 1850^ Mr. Oke 
 Spoonersays^* "On examining the matter of Small 
 
 * Provincial Medical and Surgical Journal. July 10th_, 
 1850. No. xiv. p. SGJ, ^^Practical Observations on the 
 Vaccination Question." By E. Oke Spooner, M. R. C. S., 
 Blandford. 
 
 "If we examine the Cow Pox and the Small Pox 
 microscopically, as I have done very carefiiUy in every 
 stage, we find that the essential character consists of a 
 number of minute cells, not exceeding the 10,000th part of 
 an inch in diameter, being about one-fourth smaller than 
 the globules of the blood, containing within their circum- 
 ference many still more minute nuclei, and presenting beyond 
 their circumference bud-like ceUs of the same size and 
 character as those contained within the circle. They ex- 
 actly resemble in everything except the size, the globules 
 of the yeast plant, the Torula Cerevesise. Now if we 
 examine more circumstantially the analogies of what I 
 would call the Torula Variolse with the Torula Cerevesise, 
 we observe the foUomng corresponding facts. 
 
 " What do we accomplish by inoculation as it is caUed ? 
 Simply this. We take on the top of a lancet, or an ivory 
 point, a few of these minute cells or germs, and we put them 
 
 U^' 
 
32 
 
 Pox and Cow Pox in every stag-e^ he finds its es- 
 sential character to consist of a number of minute 
 cells not exceeding^ the lO^OOOth part of an inch in 
 diameter : being about one-fourth smaller than the 
 globules of the bloody containing* within their cir- 
 cumference many still more minute nuclei^ and 
 presenting" beyond their circumference bud-like cells 
 of the same size and character as those contained 
 within the circle." 
 
 Should these observations made by Mr. Spooner 
 turn out to be correct^ they will but fulfil my an- 
 ticipations. Then again shall we see the same 
 application of imperfect vision to the limitation or 
 temporary obstruction of solid and determinate 
 knowledge. 
 
 We may reasonably expect that these bodies^ dis- 
 covered by Mr. Spooner^ should be the elementary 
 matters of disease. Their existence was predicted 
 from the probability that living matter must be the 
 agent ; moreover^ that this matter when discovered 
 
 in their appropriate nidus, the subcuticular tissue, where, 
 after a few days if they find their appropriate nutrient 
 elements, they grow and multiply/^ 
 
 Simon, Chemistry of Man, vol. i. p. 127. "Macgregor 
 ascertained that the air expired by persons ill of confluent 
 Small Pox, contained as much as ei(/ht per cent of carbonic 
 acid, and in proportion as health was restored the percentage 
 was diminished to its natural standard." Carbonic acid 
 is also produced during the process of fermentation and 
 germination. 
 
83 
 
 would be cellular^ most probably resembling* the 
 yeast plant as described by Mr. Spooner. 
 
 It was predicted that a planet would be discovered 
 in a certain position in the heavens^ because the 
 perturbations of a comet indicated an attracting 
 body in the path of the eccentric wanderer ; the 
 prediction and the fulfilment were almost simul- 
 taneous. 
 
 \^ 
 
34 
 
 SECTION II. 
 
 HISTORICAL NOTICE OF EPIDEMIC DISEASES. 
 
 The earliest notices we have of Pestilences are 
 contained in Holy Writ. The plagues which smote 
 the Eg-yptians in the time of Moses are not un- 
 worthy some comment here. Of those ten plagues, 
 four out of the number were due to the miraculous 
 appearance of myriads of the lower animal tribes, 
 in three instances of insects,* viz. lice, flies, and 
 locusts ', in the fourth, when Aaron stretched forth 
 his hand with his rod over the streams, over the 
 rivers, and the ponds, frogs came up and covered 
 the land of Egypt. In these instances living beings 
 are made the instruments in God's hand for the 
 punishment of the wicked. These plagues include 
 the second, third, fourth, and eighth. The first 
 plague is mentioned as a conversion of the waters 
 into blood. Now if we may take this expression as 
 being literal, there is no reason to suppose that this 
 blood differed in any respect from ordinary san- 
 guineous liquid^ we therefore may assume, as the 
 blood is every w^here in Scripture spoken of as the 
 life^ that this fluid was endowed with vital pro- 
 perties. 
 
 * See History of the Jews, p. 71' 
 
i35 
 
 The fifth plag'iie is described us ii murniiii among 
 beasts , and the sixth, as exhibiting* itself as '' a boil 
 breaking- forth with blains, upon man and upon 
 beast."* Now these affections bear a resemblance 
 to the diseases known to us at the present day 
 through authentic records. The Black Death of 
 the 14th century affords in its history but too awful 
 a picture of the horrors of such pestilences. In the 
 tenth plague, the smiting- of the first-born, we are 
 not told by what means it was brought about \ but 
 we have something even here to lead us to con- 
 jecture. In the second visitation of the Black 
 Death, there were destroyed a gi'eat many children 
 whom it had formerly spared, and but few women. 
 The seventh plague of hail is within our conception \ 
 as is also that of darkness, the ninth plag-ue. 
 
 It is not a little remarkable that of the ten 
 plagues, seven of them depended upon agents intel- 
 lig-ible to our comprehension j we can conceive of 
 
 * It is said by Whewell, that the murrain is supposed 
 to have fallen only on the animals which were in the open 
 pasture. — History of the Jews. 
 
 "J. S. Michael Leger, published at Vienna, in 1775, a 
 treatise concerning the mildew as the principal cause of 
 the epidemic disease among cattle. The mildew is that 
 which hums and dries the grass and leaves. It is observed 
 early in the morning, particularly after thunder-storms. 
 Its poisonous quahty, which does not last above twenty- 
 four hours, never operates but when it is swallowed imme- 
 diately after its faUing." — Mitchell on Fevers. 
 
 D 2 
 
 i/ 
 
36 
 
 the invasion of a country by myriads of loathsome 
 insects and reptiles^ and can imagine the wrath of 
 an offended Deity directing- the force of a super- 
 natural storm of hail upon a disobedient people ^ 
 and we can conjecture^ though faintly^ the con- 
 sternation of human nature on being subjected to a 
 total darkness of three days' duration^ when we 
 consider that darkness has been described^ as ^^a 
 darkness that might be felt/' 
 
 From this abstract we discover that the three 
 plagues whose causes we cannot understand^ or rather 
 upon which no light has been thrown by Scripture^ 
 bear analogies to those which we recognise^ in the 
 writings of modern authors^ as fearful pestilences. 
 
 It is now our province to reflect on the causes 
 supposed to be in operation in the three instances^ 
 which become naturally separated from the rest. 
 
 We are told that a murrain appeared among the 
 cattle^ without any preliminary step. When the 
 blains broke out upon man and beast^ Moses had 
 been previously directed by the Almighty to take 
 handfuls of the ashes of the furnace^ and sprinkle 
 them towards the heaven in the sight of Pharaoh. 
 ^' A nd it shall hecome small dust in all the land of 
 Egypty and shall be a boil breaking forth with blains 
 upon man and upon beast^ throughout all the land 
 of Egypt." 
 
 Another coincidence, in connexion with subsequent 
 pestilences, arrests the attention, on the subject of 
 the mysterious appearance on these occasions of 
 
37 
 
 matter resembling- dust being- prevalent about the 
 houses^ and on the clothes of the people. Clouds 
 also^ and showers of dust-Hke particles^ were not of 
 infrequent occurrence. Indeed^ in the summer of 
 1849^ during- the progress of the Cholera, several 
 phenomena of a similar nature were observed and 
 authenticated ; I m3^self can bear testimony to one 
 instance of the kind. It was observed by many 
 persons in my neig-hbourhood after the passag-e 
 of an ominous and lurid cloud, that as they walked 
 their clothes became covered with a singular dust- 
 like matter of very peculiar appearance. That this 
 phenomenon was not destitute of sig'nificance may 
 be g-athered from the fact, that on the night of that 
 day several severe cases of Cholera occurred, though 
 our village had been comparatively free for ten 
 days. 
 
 Hecker, in writing on the Black Death says, the 
 German accounts expressly speak of a ^^ thick 
 stinking mist which advanced from the east,* and 
 
 * " The prevalence of the south-east wind was observed 
 to be particularly favourable to the increase of both cholera 
 and influenza : and I cannot but think that this had some 
 connexion with the general tendency exhibited by the 
 former to spread from east to west. Has the morbific 
 property of this wind aught to do with the haziness of the 
 air when it prevails — a haziness seen in the country remote 
 from smoke, and quite distinct from fog? What is this 
 haze? In the west of England a hazy day in spring is 
 called a bligktJ" — Dr, Williams' Principles of Medicine, 
 
38 
 
 spread itself over Italy ; there could be no decep- 
 tion in so palpable a phenomenon." It is not 
 unworthy of mention^ that in the East successive 
 invasions of locusts '' which had never perhaps 
 darkened the sun in thicker swarms/' preceded the 
 great outbreak of this disease^ for they left famine 
 in their train. 
 
 From 1500 to 1503 in Germany and France^ 
 during" the prevalence of the sweating- sickness^ 
 spots of different colours made their appearance, 
 *'' principally red, but also white, yellow, g"rey, and 
 black, often in a very short time, on the roofs of 
 houses, on clothes, on the veils and neckerchiefs of 
 women, &c.'' Blood rain is also mentioned as 
 having occurred at this time, which consisted of the 
 aggregation of minute particles of red matter. 
 
 In the seven plagues, miraculous operations of the 
 Deity consisted in the unusual manifestation of 
 phenomena, but which in their effects are recogni- 
 zable as of clear and definite import. The miracles 
 here are, — in the mode of producing the swarms of 
 frogs, locusts, &c. but they are manifest and unmis- 
 takeable causes of plague and famine ) in the other 
 three, on the contrary, we witness only the effects, 
 the causes are hidden from us ; we may, therefore, 
 as in current events, leg'itimately investigate the 
 subject, and what better course can be adopted than 
 that which classifies the traditionary past with all 
 subsequent history. Presuming such a method of 
 research to be admitted, I have assumed that as 
 
39 
 
 the causes of the seven plagues have been distinctly 
 given^ the others^ thoug-h only mentioned in their 
 effects^ were due to causes of a nature in some 
 way to be comj)ared with their concomitants_, that 
 is to say^ if a special intervention of the Deity 
 broug-ht about a miraculous appearance of frog's, 
 lice, &c. there is but little reason to doubt that some 
 other agent was miraculously multiplied and con- 
 centrated to induce the murrain, engender the 
 blain, and smite the first-born : as if to lead us into 
 this enquiry, on the visitation of the blain in man 
 and beast, the Bible History tells us that Moses 
 threw ashes of the furnace, which became a dust 
 throughout all the land of Egypt 5 we cannot 
 imagine that this simply as ashes could have caused 
 the blain, we may conclude that by some special 
 miracle, either the ashes were converted into a 
 specific form of matter capable of inducing the effects 
 recorded, or that an independent septic matter was 
 generated for the purpose. If the latter, the act of 
 throwing the ashes of the furnace into the air may 
 have been intended to signify that the extremely 
 minute division of the particles when thus cast into 
 space, typified the inscrutable and hidden nature of 
 the matter endowed with such marvellous proper- 
 ties.* 
 
 * We are to understand also that some peculiar opera- 
 tion took place of a nature difficult to comprehend, which 
 seems also to typify reproduction, for the handftds of 
 
40 
 
 Further on in the book of Leviticus are passages 
 which I cannot forbear transcribing-^ for they point 
 out to us most indubitably a line of enquiry in 
 reference to diseases of a contag-ious nature. 
 
 ^^ The g-arment also that the plague of leprosy is 
 in^ whether it be a woollen g-arment^ or a linen 
 g-arment^ whether it be in the warp or woof, of linen 
 or of woollen^ whether in a skin^ or in any thing- 
 made of skin^ and if the plag-ue be g-reenish or 
 
 reddish in the garment it is a plague of 
 
 leprosy^ and shall be shewed unto the Priest^ and 
 the Priest shall look upon the plague and shut up it 
 that hath the plague seven days ; and he shall look 
 on the plague on the seventh day ^ if the plague be 
 
 spread in the garment^ either in the warp^ &c 
 
 the plague is a fretting leprosy^ it is unclean. He 
 
 shall therefore burn that garment wherein 
 
 the plague is^ for it is a fretting leprosy ; it shall 
 be burnt in the fire. And if the Priest shall look, 
 and behold, the plague be not spread in the garment 
 
 then the Priest shall command that they 
 
 wash the thing wherein the plag-ue is, and he shall 
 shut it up seven days more : and the Priest shall 
 look on the plague, after that it is washed : and 
 behold if the plague have not changed his colour, 
 and the plague be not spread, it is unclean ; thou 
 
 ashes which Moses threw into the air became a dust in all 
 the land of Egypt, thus signifying an enormous reproduc- 
 tion of atomic matter. 
 
41 
 
 shalt burn it in the fire ; it is fret inward ; whether 
 it be bare within or without. And if the Priest 
 look and behold the plag-ue be somewhat dark after 
 the washing- of it^ then he shall rend it out of the 
 
 g-arment and if it appear still in the g"ar- 
 
 ment either in the warp or the woof it is 
 
 a spreading plag-ue : thou shalt burn that wherein 
 
 the plagiie is with fire. And the garment 
 
 which thou shalt wash^ if the plag-ue be departed 
 from them^ then it shall be washed the second time 
 and shall be clean.'' — Chap. xiii. 47 — 6S. 
 
 Again in Deuteronomy. The curse for disobe- 
 dience : ^^ The Lord shall make the pestilence cleave 
 to thee until he have consumed thee from off the 
 land — The Lord shall smite thee with a consump- 
 tion^ and with a fever^ and with an inflammation, 
 and with an extreme burning, and with the drought, 
 and with blasting, and with mildew, and they shall 
 pursue thee until thou perish. — The Lord shall make 
 the rain of thy land powder and dust : from heaven 
 shall it come down upon thee until thou be de- 
 stroyed." 
 
 It may be said, and I doubt not will be said, all 
 this is unnecessarily dragging the sacred volume 
 into an enquiry totally foreign to its general tenor ; 
 on the contrary, however, I maintain by that Book 
 we are to learn the ways of God to man, and further, 
 that no study can impress mankind with so awful, 
 so terrific an idea of his responsible position, as that 
 which leads him into the investigation of the causes 
 
42 
 
 by which the Almig-hty^ doubtless in His wisdom^ 
 has thoug'ht fit at various epochs of this world's 
 history^ to place man face to face with pestilence^ 
 famine and sudden death. 
 
 There is no man would less willingly than 
 myself introduce profanely the revelations of Scrip- 
 ture. The observations here made are not^ therefore, 
 intended for lig-ht or heedless controversy ; if they 
 have a significance of any import, let them be al- 
 luded to in the same spirit with which they have 
 been quoted 3 if they convey nothing* for approval to 
 the reader, let silence rest upon them. To those 
 who would fain disreg'ard my request, let me recall 
 to their minds the veneration which from childhood 
 I trust we have always felt on hearing" or seeing" 
 those two words— Holy Bible. 
 
 It is yet to be determined, whether the g"reenish 
 or reddish appearance of the g-arment spoken of, 
 as being" contaminated with the plag'ue of the leprosy 
 had any specific relation to the disease itself. The 
 priest orders that the g'arment shall be shut up 
 seven days, and on the seventh day, if the plag-ue be 
 increased, by which, of course, is meant if the 
 g-reenish or reddish colour have increased, and from 
 which we may g"ather that a power of spontaneous 
 increase was possessed by the matter, such a result 
 indicated a fretting" leprosy, and the g"arment was 
 to be burnt. Ag"ain, thoug"h there may have been 
 no increase, but a persistence of the coloured matter 
 after shutting- up and washing" the garment, it is to 
 
43 
 
 be burnt^ for it is fret inward^ sig-nifying-^ that the 
 g-erms of the affection are still there^ and may soon 
 increase. Other rules follow in reference to the 
 plag'ue of leprosy^ and the mode of deciding" whether 
 an article be unclean or clean is definitely laid down^ 
 but our purpose is served in mentioning- the above^ 
 to shew that in the time of Moses the spontaneous 
 increase of certain minute multiplying* g-erms was 
 supposed to have a close connexion with disease. 
 It is equally clear^ that the priests were aware by 
 the order given them^ that if the ordinary modes of 
 purifying- articles of clothing- failed in their effect^ 
 the safest and surest method of destroying- infectious 
 matter was to resort to the practice of consuming- by 
 fire all materials capable of propagating* an infectious 
 malady. 
 
 The facts above noticed^ accurately correspond to 
 what we now know as applicable to the matter of 
 infectious and contag-ious maladies. It is a rule^ I 
 believe universally adopted throughout the Poor- 
 houses of this country^ to put the clothes of all 
 persons about to become residents in these estab- 
 lishments, into ovens, where they are submitted to a 
 temperature incompatible with the existence of either 
 animal or veg-etable life. By this means all living- 
 matters are destroyed, but the fabrics and inorg-anic 
 matters retain their properties intact. This simple 
 proceeding, I am credibly informed, is an effectual 
 preventive of contamination by articles of clothing, 
 a desideratum of no small importance, when it is 
 
44 
 
 remembered that the diseases among- the poor owe 
 much of their inveteracy to the accumulation of eifete 
 org-anic matters about their persons and clothes. 
 
 A few more observations are called for on the 
 quotation from Deuteronomy^ in which allusion is 
 made to living- matter being- an ag-ent in the pro- 
 duction of disease. In the curse upon the children 
 of Israel for disobedience^ we read that they are to 
 be smitten with mildew. No further information^ 
 however^ is vouchsafed to us^ nevertheless^, we can 
 conceive the wretched condition of those on whom 
 the curse mig-ht fall. Ag-ain^ we find in a continu- 
 ation of this curse that the Almig-hty uses means 
 such as He adopted in the sixth plague of the 
 Eg-yptians. The ashes of the furnace became a 
 small dust in all the land of Egypt^ breaking- forth 
 with blains upon man and beast. In the curse of 
 the Israelites the words are : '' The Lord shall make 
 the rain of thy X^^tA powder and dust: from Heaven 
 shall it come down upon thee until thou be de- 
 stroyed." 
 
 It mig-ht be conjectured that the absence of rain 
 would be sufficient to account for the extinction of 
 the people on whom the curse was pronounced^ by 
 the famine and droug-ht necessarily attendant upon 
 the loss of moisture. But this does not appear to be 
 the meaning of the passage^ for the powder and 
 dust are mentioned as the ag'ents of destruction ; 
 besides^ in the continuation of the curse^ the locust 
 is to destroy the grain, the worm the g-rapes, and 
 
45 
 
 the olive is to shed his fhiit ; we may thus take for 
 granted that drought and famine are not to be 
 caused by the showering- of powder and dust^ it 
 must consequently be supposed that the effects of 
 the dust in the instance of the Eg-yptians are to be 
 compared and classified with those of the dust which 
 smote the Israelites. 
 
 As far then as Sacred History conducts us in the 
 enquiry^ concerning* the causes of pestilences^ we 
 gain encouragement in the belief that living germs 
 are the active agents^ for in the case of the leprosy^ 
 we have evidence of reproduction in connexion 
 with infection^ which^ if our line of argument be 
 tenable^ amounts to demonstration; then^ in the 
 other instances of the plagues^ by boils and blains, 
 they distinctly bear comparison with the accounts 
 given by profane writers^ of the visitations of pesti- 
 lences on the earth, subsequently to those mentioned 
 in Scripture history. 
 
 This leads now to the consideration of recorded 
 facts observed and noted during the various Epi- 
 demics in the early and subsequent periods of 
 Man^s History, as given by those on whom reliance 
 may be fairly placed. 
 
 Setting aside the uncertain information contained 
 in the writings of the Chinese,* a people whose 
 
 * The Chinese affect to trace the origin of Small Pox 
 back to a period of at least 3000 years, or 20 years beyond 
 the era of the Trojan war, 1212, A. C. 
 
46 
 
 progress in the science and practice of Medicine 
 has nothing- to commend it (even as it is at the 
 present day) to the notice either of the ph3^sician or 
 the historian^ unless it be to the latter as a mark of 
 peculiarity both in a social and political point of 
 view_,— passing* also over the Eg-yptians^ the Ara- 
 bians^ and the Greeks^ — and even Hippocrates 
 himself, we are driven to the Romans for any 
 authentic or precise notice of Epidemic Affections. 
 It has been attributed to Hippocrates that he 
 predicted the appearance of the Plag-ue at Athens, 
 
 The Chinese pretend to discriminate no less than 40 
 different species of Small Pox. 
 
 " They also pretend to discover whether a person has 
 died by violence or from natural causes^ not only after the 
 body has been some time interred and decomposition of 
 the softer parts has commenced, but even after the total 
 disappearance of the soft parts, and when the dry skeleton 
 alone is left." — For the process, see Hamilton s History of 
 Medicine, vol. i. p. 31. 
 
 To give some notion of the state of Medical Science 
 among the Chinese, I may quote the following: "The 
 theory of the circulation of the blood, Du Halde affirms, 
 was known by the Chinese about 400 years after the 
 deluge ; be this assertion veracious or not, no correct 
 knowledge up to the present day, do the nation possess of 
 the circulating system of the human frame." — China and 
 the Chinese, Henry Charles Sirr, M, A. 
 
 According to their anatomy, the trachea extends from 
 the larynx through the lungs to the heart, whilst the 
 oesophagus goes over them to the stomach. 
 
47 
 
 and that when it was introduced into Greece he 
 dispelled it^ " by purifying- the air with fires into 
 which were thrown sweet-scented herbs and flowers 
 along- with other perfumes."* But little advantag-e 
 can be derived from enquiries concerning' the first 
 appearance of any disease^ for the probability of 
 discovering- the primary cause is certainly a hope- 
 
 * "And Aaron took as Moses commanded, and ran 
 into the midst of the congregation : and behold the plague 
 was begun among the people; and he put on incense 
 and made an atonement for the people. And he stood 
 between the dead and the hving, and the plague was 
 stayed/^ — Numbers. 
 
 The practice of burning scented herbs has been observed 
 in all times during an invasion of the plague, as a means 
 of protection. Also wearing perfumes and aromatic 
 preparations has been recommended. Whether they have 
 any counteracting influence, it is impossible to say. 
 
 Virgil in the third Georgic speaks of a murrain among 
 cattle. He says, if any wore a vestment made of wool 
 from an infected sheep, fiery blains and filthy sweat 
 overspread his body, and ere long a pestilential fire preyed 
 upon his infected limbs. 
 
 In his directions for preserving the health of flocks he 
 
 " Disce et odoratam stabulis accendere cedrum.^' 
 
 The motive for burning the fragrant cedar is not men- 
 tioned ; we cannot doubt but it was a good one, and having 
 some great practical utility, from the following line — 
 
 " Galbaneoque agitare graves nidore chelydros." 
 
48 
 
 less case^ if attempted by means of the writings 
 of ancient authors^ when it is recollected that with 
 all the science and learning- of the ancient Eg-yp- 
 tianSj the use of optical instruments was not 
 comprised among* the paraphernalia of their arts. 
 The knowledg-e that was limited to the powers of 
 natural vision^ where the foundation of knowledg-e 
 is based upon facts obtained through the aid of that 
 penetrator of nature's secrets^ the microscope^ offers 
 no advantag-es to the student of the present day. 
 
 To say that a disease commenced in the East and 
 travelled westward^ and at length found a habitation 
 and a name in every part of the globe^ is no more 
 than to say that disease is coeval with the fall of 
 man. The cause is as much hidden in the region 
 of its birth^ as in that where it sojourns for a time. 
 The cause of the sweating sickness was as much a 
 mystery in England as in all the other nations of 
 Europe^ which were visited by its devastating power. 
 And these observations apply with as much force to 
 one disease as another; for even our indigeno,us 
 ague^ originating in some places so limited that the 
 shadow of a passing cloud may mark the boundary 
 of its dwelling place^ as inscrutably evades our 
 vigilance^ with all the appliances that art can bring 
 to our assistance^ in endeavouring to evoke its extra- 
 ordinary properties under the cognizance of our 
 senses. 
 
 ' If we weigh the air which carries the poison^ or 
 analyze it by the most delicate chemical tests, or 
 
49 
 
 take- the weight of the atmosphere which is charged 
 with it^ or if we take the blood which carries the 
 germs of the disease to the tissues of the bod}^^ 
 and submit them after the work of destruction is 
 accomplished^ to the most rigid inspection, we can 
 but exclaim, 
 
 " These are Thy marvellous works !" 
 
 and confess our total inability to fathom the un- 
 bounded. 
 
 If then no practical advantage can accrue from 
 investigating the writings of the ancients on these 
 subjects, beyond comparing their historical statements 
 with those of more recent date, our purpose will be 
 served by occasionally embodying any remarkable 
 observations of the former with those of the latter. 
 
 In proceeding with this course it were better to 
 confine our minds chiefly to two diseases which ap- 
 pear from history to have been known from the 
 earliest periods, these are the Plag^ue and the Small 
 Pox, mentioning other diseases only en route. 
 
 Passing then, to the sixth century of the Christian 
 era for the first distinct and connected account of 
 the Plague, it appears from a host of testimony, 
 that the history of this disease, as given by Proco- 
 pius, well merits our attention. Drs. Friend and 
 Hamilton, in their Histories of Medicine, and Gibbon, 
 in his History of Rome, are equally warm in their 
 praise of Procopius : the latter says, he " emulated 
 the skill and diligence of Thucydides in the descrip- 
 
 E 
 
 i^ 
 
50 
 
 tion of the Plague at Athens." The account g-iven 
 by Procopius of this disease^ does not differ materially 
 from that g"iven by subsequent eye-witnesses of 
 similar pestilences. Its point of orig-in is clearly 
 marked^ and its mode of dispersion in all directions 
 distinctly traced from ^^ the neig'hbourhood of Pelu- 
 sium^ between the Serbonian bog* and the eastern 
 channel of the Nile/' It commenced in the year 
 54:2, It rag-ed in Constantinople in the following- 
 year^ and it was in this city that our historian 
 g-athered the materials w^hich are handed dow^n to 
 us. When^ however^ w^e anxiously look for any 
 explanation as to the cause of the malady^ we are 
 told that it must have been a direct visitation from 
 Heaven^ in consequence of the eccentric characters 
 exhibited in its wide-spreading* influence^ in not 
 yielding" to the scrutiny nor bending* to the laws 
 known to prevail^ and to reg-ulate the course of 
 other diseases : neither country nor clime^ ag-e nor 
 sex^ the strong- and healthy^ nor the weakly and 
 previously diseased^ could be said to be free from 
 its indiscriminate destruction. 
 
 But some phenomena preceding* the outbreak of 
 the pestilence are observed as coincidences by all 
 authors. Gibbon thus writes : ^^ I shall conclude 
 this chapter with the comets^ the earthquakes, and 
 the plag-ue which astonished or afflicted the ag-e of 
 Justinian. '^ From the accounts g-iven b}^ this 
 author^ earthquakes for some years had been threat- 
 ening- and destroying- many portions of the g-lobe. 
 
51 
 
 that in the ruins of cities and in the chasms of the 
 earthy great was the sacrifice of human life. Con- 
 stantinople^ which suffered so severely from the 
 plag'ue is said to have been shaken for forty days. 
 These g-reat disturbances of the g-lobe have been 
 always looked upon as indicating* other and import- 
 ant influences of a secret or hidden nature ; these 
 impressions on the minds of the people are traceable 
 throughout the histories of all epidemics^ and have 
 been sufficiently distinct among* the people of our 
 own time^ preceding- and during" the period of 
 infliction. 
 
 From this short notice of the Plag-ue of 543^ I 
 pass to the ninth century^ when Rhazes^ the Arabian 
 physician^ endeavoured to enlighten the world on 
 the subject of Small Pox.* In quoting his opinions^ 
 I am not to be understood as subscribing* to them, 
 but merely endeavouring to point out some peculiar 
 and interesting observations. 
 
 First, then, Rhazes attributes the disease to a 
 condition of the blood, which he thus describes, to 
 shew how it happens that in infancy and childhood 
 the disease is most prevalent, and that old age is 
 
 * The earliest mention of this complaint upon which 
 rehance can be placed, is an ancient Arabic MS. preserved 
 in the pubUc library at Ley den. ^^ This year, in fine, the 
 Small Pox and Measles made their first appearance in 
 Arabia." The year alluded to being that of the birth of 
 Mahomet, or the year 572 of the Christian sera." 
 
 Hamilton's History of Medicine^ vol. i. p. 215. 
 E 2 
 
no 
 
 least liable to the affection.* " The blood of infants 
 and children may be compared to mustj in which the 
 coction leading- to perfect ripeness has not yet begun^ 
 nor the movement towards fermentation taken place ; 
 the blood of young- men may be compared to must 
 which has already fermented and made a hissing- 
 noise^ and has thrown out abundant vapours and 
 its superfluous parts^ like wine which is now still 
 and quiet^ and arrived at its full streng-th^ and as to 
 the blood of old men^ it may be compared to wine 
 which has now lost its strength^ and is beg-inning- 
 to g-row vapid and sour.'' 
 
 ^^ Now the Small Pox arises when the blood 
 putrifies and ferments^ so that the superfluous vapours 
 are thrown out of it, and it is chang-ed from the 
 blood of infants which is like must, into the blood of 
 young- men which is like wine perfectly ripened : 
 and the Small Pox itself may be compared to the 
 fermentation and the hissing- noise which take place 
 at that time.'' 
 
 But the cause of the disease is simply alluded to 
 by this author^ as depending- upon ^^ occult dispo- 
 sitions in the air/' and as he speaks here of Measles 
 with the Small Pox he g-oes on to say — ^^ which 
 necessarily cause these diseases and predispose 
 bodies to them." This notion of Rhazes that there 
 is some peculiar condition of the blood which favours 
 a process resembling- fermentation is not without 
 interest. The circumstance that individuals are not 
 
 * Dr. W. A. GreenhilFs translation. 
 
53 
 
 usually liable to a second attack of the disease^ no 
 doubt directed the attention of this physician to 
 compare the process of fermentation with disease of 
 such a nature^ seeing* that when the whole of the 
 saccharine matter was converted into spirit^ the 
 hissing" noise^ as he calls it^ or the diseng-agement 
 of carbonic acid g-as would cease^ and the capacity 
 for fermentation be entirely g-one. So that the 
 occult conditions of the air^ their power of inducing* 
 a disease^ and multiplying^ the matter capable of en- 
 g'endering' a similar affection^ stood in the mind of 
 Rhazes as analog-ous if not identical phenomena. 
 
 We pass now without further comment to the 
 epidemics of the Middle Ag^es ; and here the work 
 of the philosophical Hecker leaves us little else to 
 desire in the way of information^ as far as it is ob- 
 tainable from published records. From the manner 
 in which he has g-rouped the facts which presented 
 themselves to his mind in the course of a most 
 laborious research^ he has saved the student of this 
 subject much toil in acquiring- matter for reflection ; 
 he has here but to read and dig-est. 
 
 I know not how to select from this invaluable 
 work the most striking- passages^ to strengthen 
 and support my hypothesis, for not a page is desti- 
 tute of facts corroborative of the doctrine that vital 
 germs are the material agents of pestilential dis- 
 orders. The opening paragraph to the Black 
 Death is^a most cogent illustration of the assertion ; 
 it is, as it were, the theme of the work. " That 
 
54 
 
 Omnipotence^ which has called the world with all 
 its living creatures into one animated being, espe- 
 cially reveals himself in the desolation of great 
 pestilences. The powers of creation come into violent 
 collision ; the sultry dryness of the atmosphere , 
 the subteiTanean thunders ; the mist of overflowing" 
 waters are the harbing-ers of destruction. Nature 
 is not satisfied with the ordinary alternations of life 
 and death^ and the destroying ang-el waves over man 
 and beast his flaming* sword .'^ 
 
 I must here apolog-ise for larg-e transcripts from 
 Hecker's work^ for neither could I command the 
 amount of knowledg^e there displayed^ nor use such 
 appropriate languag-e as the learned translator has 
 employed. 
 
 It is not doubted that the Black Death was an 
 Oriental plagne^ only of more than usual severity, 
 and wider spread influence of the infectious nature 
 of this disease^ and the active properties of the matter 
 producing" it. Hecker says^ ^^ articles of this kind — 
 bedding" and clothes— removed from the access of 
 air^ not only retain the matter of contagion for an 
 indefinite period^ but also increase its activity, and 
 engender it like a living being, frightful ill con- 
 sequences followed for many years after the first 
 fury of the pestilence was past."* 
 
 * The Black Assize at Oxford, 1572, is an instance in 
 which a pestilential vapour suddenly appeared in the court, 
 '^whereby the judge, several noblemen, and more than 
 300 others, died within three days.^' 
 
As extraordinary atmospheric and telluric phe- 
 nomena preceded the Plag-ue in the time of Justinian^ 
 so do we find similar instances recorded as the 
 precursor of a similar visitation 700 years later. 
 I am concerned more with those circumstances 
 which refer more especially to my subject^ viz, the 
 development of org^anic matter^ and the peculiar 
 odours of the atmosphere^ the latter being* evidence of 
 some foreign and unusual production in our respira- 
 tory media. ^^ On the island of Cyprus^ before the 
 earthquake^ a pestiferous wind spread so poisonous 
 an odour^ that many being- overpowered by it^ fell 
 down suddenly and expired in dreadful agonies. 
 A thick stinking" mist advanced from the east^ and 
 spread itself over Italy.'' 
 
 " Of an unaccountable vapour suddenly coming, I have 
 this relation from Richard Humphrey, my neighbour, and 
 a man of veracity, that on Wednesday, April 27, 17^7^ as 
 he and one Walter, were travelling a-foot from Canterbury ; 
 when they came to Rainham, they were assaulted with 
 such a strong loathsome stink, as he thought was like the 
 stench from a corrupted human corpse. They were so 
 offended at it, as thinking it was from carrion in that 
 town, that they would not stay there to rest and refresh 
 themselves, but travelled on for about two hours, mostly 
 in the stench, but sometimes out of it, till they came to 
 the hill that leads down to Chatham : and there they 
 went clear out of it and smelt it no more/^ — Dr. Fuller. 
 
 It appears that these persons did not fall sick of any 
 disease, but the fact of itself is remarkable enough. 
 
56 
 
 It is probable that the atmosphere contained 
 foreig-n and sensibly perceptible admixtures to a 
 great extent^ which^ at least in the lower reg-ions, 
 could not be decomposed or rendered ineifective by 
 separation. In 1348 an unexampled earthquake 
 shook Greece^ I^aly^ and the neig'hbouring* coun- 
 tries. During- this earthquake the wine in the 
 casks became turbid, a proof that chang-es causing" 
 a decomposition of the atmosphere had taken place. 
 " The insect tribe was wonderfully called into life^ 
 as if animated being-s were destined to complete the 
 destruction which astral and telluric powers had 
 beg-an." 
 
 " The corruption of the atmosphere came from the 
 east^ but the disease itself came not upon the wings 
 of the wind^ but was only excited and increased by 
 the atmosphere where it had previously existed.^' 
 
 " The most powerful of all the spring's of the dis- 
 ease was contagion ^ for in the most distant coun- 
 tries, which had scarcely yet heard the echo of the 
 first concussion, the people fell a sacrifice to organic 
 poison^ the untimely offspring" of vital energ-ies 
 thrown into violent commotion." 
 
 " After the cessation of the Black Plag-ue, a greater 
 fecundity in Avomen was every where remarkable, a 
 gTand phenomena, which from its occurrence after 
 every destructive pestilence/proves to conviction the 
 prevalence of a higher power in the direction of 
 general organic life." 
 
57 
 
 In the article Contagion, of the Essay^ Sweating- 
 Sickness : " Most fevers which are produced by 
 g-eneral causes^ propag-ate themselves for a time 
 spontaneously." ^^ The exhalations of the affected 
 become the g"erms of a similar decomposition in those 
 bodies which receive them^ and produce in these a like 
 attack upon the internal org-ans^ and thus a merely 
 morbid phenomenon of life, shows that it possesses 
 the fundamental property of all life, that of propa- 
 gating itself in an appropriate soil. On this point 
 there is no doubt, the phenomena which prove it have 
 been observed from time immemorial, in an endless 
 variety of circumstances, but always with a uniform 
 manifestation of a fundamental lawJ^ 
 
 Mead^ in his Essay on the Plag^ue^ makes many 
 observations of great interest and worthy a physi- 
 cian of eminence -, and where^ in recent times^ shall 
 we look for any more definite information concerning 
 the causes of pestilences ? It is not a little sing-ular 
 that at the time this book was published^ it was 
 read with such avidity that it went throug"h seven 
 editions in one year.* From this circumstance we 
 may gather that the public generally took a lively 
 and proper interest in a subject that was not only 
 of domestic^ but national importance. Whether 
 this interest was stimulated by the fact that the 
 w ork was written expressly by order of the govern- 
 
 * Hamilton's History of Medicine. 
 
58 
 
 ment^ it is now impossible to say^ at any rate much 
 credit is due to the Lords of the Reg-ency for having- 
 placed so important a duty upon one so thoroughly 
 and in every way so duly qualified for the task as 
 Dr. Mead. It had been well if some of the advice 
 g-iven at that time^ as means of protection ag-ainst 
 the Plag-ue^ had been applied and put in force 
 during- the late visitation of epidemic Cholera^ for^ 
 however the minds of some may be convinced of 
 the non-contag-iousness of Cholera_, there are many 
 who hold a different opinion^ and all will acknow- 
 ledg-e^ that if not strictly a contag-ious affection^ it 
 is clearly proved to be capable of being* carried from 
 place to place^ or to use Dr. Copland's words^ it is 
 '' a portable disease." But this is not the place to 
 discuss the subject of contag-ion^ allusion will be 
 made to it hereafter. To return^ Mead's expressions 
 are sing-ularl}^ illustrative of the vital power pos- 
 sessed by the g-erms of disease^ he saj^s^ ^^ There 
 are instances of the distemper's being- stopt by the 
 winter cold^ and yet the seeds of it not destroyed^ 
 but only kept unactive^ till the warmth of the fol- 
 lowing spring has given them new Ufe and force. 
 His confession as to the hidden cause of the disease, 
 is worthy transcribing- : " We are acquainted too 
 little with the laws, by which the small parts of 
 matter act upon each other, to be able precisely to 
 determine the qualities requisite to chang-e animal 
 juices into such acrimonious humours, or to explain 
 
59 
 
 how all the distiug-uishing" symptoms attending* 
 the disease are produced."* 
 
 On the spread of the Plague is the following : — 
 " The plag-ue is a real poison^ which being- bred in 
 the southern parts of the world^ maintains itself 
 there by circulating* from infected persons to g*oods^ 
 that when the constitution of the air happens to 
 favour infection^ it rag-es with great violence/' 
 Contagious matter is lodg-ed in goods of a loose and 
 soft texture, which being packed up, and carried 
 into other countries, let out, when opened, the 
 imprisoned seeds of contagion, and produce the 
 disease whenever the air is disposed to give them 
 force, '^ otherwise they may be dispersed without 
 any considerable ill effects." Gibbon thus speaks of 
 the above quoted work : " I have read with pleasure 
 Mead's short but elegant Treatise concerning Pes- 
 tilential Disorders ;" many also might read it at 
 the present day with infinite advantage. Mead 
 most satisfactorily combats the opinions of the 
 French physicians who maintained the non-conta- 
 giousness of the Plag^ue. Experience proves beyond 
 doubt, that certain conditions of atmosphere, of 
 
 * It has been said, that '' an induction once carefully 
 drawn, is as perfect from a single instance as it is from 
 ten thousand, and that it is only an uncultivated mind 
 which requires a load and accumulation of knowledge to 
 assist his thoughts.^' — Sewell '^ on the Cultivation of the 
 Intellect.'' 
 
60 
 
 which we are ig-norant^ favour the growth and 
 increase of pestilences as they do of all veg-etation. 
 
 Dr. Bancroft was of opinion that specific conta- 
 gions are each and severally creatures of Divine 
 Wisdom, as distinctly and desig-nedly exerted for 
 their production, as it was to create the several 
 species of animals and veg-etables around us. 
 
 The indigenous fever of Ireland, which has 
 several times shewn itself in an epidemic form, 
 appears to have been as fatal, as the Plag*ue in the 
 South of Europe. Its devastations have generally 
 been associated or preceded by famine and g'eneral 
 distress. Dr. Harty, writing* in 1820, says that 
 thrice within the last eighty years has the same 
 fever appeared in its epidemic character. In the 
 year 1741 Ireland lost 80,000 of her inhabitants 
 from this cause. It is a maculated typhus, and 
 considered to be a special product of the Emerald 
 Isle. It has been shewn that fever began to exceed 
 its ordinary rate in those places first where famine 
 and want of employment were most severely felt,* 
 and that in such places and under such circum- 
 stances, it was most prevalent and fatal. The 
 physicians generally believed it to have been spon- 
 taneously produced and not to have been imported. 
 In the last Famine Fever of Ireland, Liverpool and 
 several other places suffered severely from the 
 
 * See Dr. Alison's Pamphlet on the Fever in Edin- 
 burgh. 
 
61 
 
 importation of their Channel neighbours with the 
 disease in some instances^ and the infection in 
 others about their persons. Hitherto these have 
 to all appearance been the limits of the affection ; 
 we know not^ however^ how soon the time may come 
 when the invisible bonds which have thus chained 
 the disease to certain localities may be severed^ and 
 spreading" itself like other pestilences in an ag'g'ra- 
 vated form^ attack this country as a last and crown- 
 ing* act of retributive justice. At present it has 
 but cost us money and reg'rets^ but if the history of 
 pestilences is to be heeded^ there are many tokens 
 which seem to indicate that a few slight concurrent 
 circumstances only are wanting^ to bring the full 
 force of this disease upon us ; then will there be a 
 sacrifice of life. Edinburgh and other towns of 
 Scotland have had some visitations already^ our- 
 selves but slightly^ but let our labouring population 
 suffer to any large extent for want of work^ and we 
 shall inevitably be the sufferers from that fever 
 which in consequence of general destitution is now 
 always more or less prevalent in Ireland. 
 
 The Sweating Sickness prevailed in England 
 alone at first^ but at length sought foreign victims. 
 The Cholera is an exotic disease^ as well as the 
 Plague^ but they occasionally have visited our 
 shores^ and their seeds remain among us. The 
 Small Pox is now even not known in some parts of 
 the world^ but when once it is established^ who can 
 predict the period of its first appearance in an 
 
^ 
 
 6S 
 
 epidemic form. The history of the disease informs 
 us that in all the countries where it has been 
 introduced^ sooner or later an epidemic has seized 
 the inhabitants. 
 
 A disease previously unknown in India appeared 
 at Rangoon in the year 1824^ which obtained the 
 name of Scarlatina Eheumatica. Four years after- 
 wards it attacked the Southern States of North 
 America^ and thoug'h the disease was so impartial 
 as scarcely to spare a single individual of any town 
 to which it extended its influence^ it was not accom- 
 panied with that mortality which has usually been 
 the characteristic of wide spread epidemics. 
 
 There is one peculiar feature of all epidemics 
 which may be here mentioned as indicative of some 
 definite^ thoug'h at present unaccountable cause^ 
 operating' in the sudden suppression of the disease 
 after a certain period of duration. This distinctive 
 character may almost be considered as a law in 
 reference to these affections , if we take three dis- 
 tinct diseases^ the Plag-ue^ the Irish Fever and the 
 Cholera^ we find the rule apply to all. Of the latter 
 disease we have so recently been witnesses^ that I 
 need not quote authorities on this point concern- 
 ino* it. In Dr. Patrick Russell's work on the 
 Plag'ue at Aleppo I find the following- remarkable 
 passage. After alluding- to the great increase of 
 pestilential effluvia that there must be towards the 
 close of an epidemic^ compared with the amount at 
 the onset of the disease^ and expressing his astonish- 
 
63 
 
 ment that so many escape infection^ he says : '^ The 
 fact^ however unaccountable^ is unquestionably 
 certain \ the distemper seems to be extinguished by 
 some cause or causes equally unknown^ as those 
 which concurred to render it more or less epidemical 
 in its advance and at its heio-ht." He then mentions 
 that in Europe the sudden cessation may be partly 
 attributable to the measures adopted for preventing- 
 its extension \ but ^^ at Aleppo^ where the disease is 
 left to run its natural course^ and few or no means 
 of purification are employed^ it pursues nearly the 
 same progress in different years ) it declines and 
 revives in certain seasons^ and at lengthy without 
 the interference of human aid^ ceases entirely." 
 
 The expressions of Dr. Harty on this subject^ in 
 connexion with the Irish Fever^ would apply as w^ell 
 to all other epidemics : '' It is a fact^ that though 
 every diversity of management was resorted to for 
 effecting the suppression of the disease^ yet^ never- 
 theless^ there was an almost simultaneous and 
 apparently spontaneous decline of the epidemic in 
 the various and most remote parts of Ireland. 
 It is not an easy matter to offer a satisfactory 
 explanation of this circumstance^ some general cause 
 must no doubt have influenced the subsidence of the 
 disease, yet that cause could not be atmospheric^ 
 inasmuch as the decline, though it might be said to 
 be simultaneous^ was not sufficiently so to admit of 
 that explanation." 
 
64 
 
 SECTION III. 
 
 THE DISPERSION OF PLANTS AND DISEASES. 
 
 The dispersion of Diseases and the dispersion of 
 Plants^ exhibit analogies which mig-ht be little 
 expected^ on a superficial view of the enquiry. 
 
 We are led to believe^ that the earth as a whole^ 
 was not covered with veg'etation in a day^ the g'eo- 
 log-ical history of this planet is one of development, 
 and though at first sight this expression of opinion 
 may appear to savour of doubt in the Mosaic 
 record, a more extended acquaintance with the sub- 
 ject, favours rather and confirms Scripture history. 
 
 As the peopling of the earth has been a gradual 
 process with the animal creation, so has it been 
 also with the vegetable kingdom. We see at the 
 present day, that plants by various means of transit 
 from place to place, multiply themselves on new 
 soils and in new climes, the same with animals. By 
 other means we observe, or can trace, the extinction 
 from various localities and countries, of members 
 of both the animal and vegetable kingdom. 
 
 We learn that originally this planet had ^ tem- 
 perature much higher than at present, and that the 
 variation of temperature between the equator and 
 the poles, which we now witness, did not obtain 
 in the earlier condition of the globe. We are given 
 to understand, and not without considerable proof, 
 
0;j 
 
 if not demonstration^ that the earth was a vast bog*^ 
 in ^\hich rank ^eg-etation g-rew^ and in which the 
 ichthyosauri and plesiosauri^ must have floundered 
 about as unwieldy and loathsome bodies. We can 
 readily conceive a condition of atmosphere at this 
 time to have been loaded with pestiferous vapours 
 of an organized nature ; it is entirely in accordance 
 with all we know^ that it should have been so. 
 Allied forms of plants to those now in existence^ 
 are found in the form of fossils^ by which com- 
 parisons are made^ but how the transition into the 
 present Flora took place^ or at what period^ it is 
 impossible to say. That these plants should have 
 been entu*ely destroyed during* the revolutions of 
 the earth by earthquakes^ and their consequences ; 
 the collection of waters into the vacuities formed^ 
 and their draining- off* from other places by eleva- 
 tions of the land^ is not to be dwelt on without 
 astonishment ; then ag-ain the ultimate changes of 
 temperature on the surface of the earth, may have 
 been another element in the history of their extinc- 
 tion. But if we may be allowed to imag-ine that there 
 were org-anic germs floating in the vapours of the 
 atmosphere, these would hardly be subject to the same 
 influences as those which depended solely on their 
 fixation to the soil for subsistence. The atmosphere, 
 their native element, being influenced by the com- 
 motions from below, would be agitated ; vortiginous 
 currents would be established, hurricanes would 
 sweep over the stagnant pool and reeking morass, 
 
 F 
 
and the higher regions of the air might have thus 
 given protection to these subtle germs^ while almost 
 a total extinction of the elegant ferns^ the stately 
 palm^ and the towering cane was in course of pro- 
 cedure. Then when the strife of the earth and 
 elements had subsided, these would descend with 
 the gentle breezes^ and again find in various spots 
 a local habitation — 
 
 '^ Where blue mists, through the unmoving atmosphere. 
 Scatter the seeds of pestilence and feed unnatural vege^ 
 tation" 
 
 In the new era^ when the earth took its present 
 physiognomy^ who shall say whether much of the 
 pestiferous matter may not have been enclosed and 
 condensed in the bowels of the earthy and when it 
 is remembered^ that earthquakes and convulsions of 
 nature^* have invariably preceded the outbreak of 
 
 * Earthquakes have in all times been considered to have 
 some connexion with pestilences. " A most grievous pes- 
 tilence broke out in Seleucia, which from thence to 
 Parthia, Greece, and Italy, spread itself through a great 
 part of the world, from the opening of an ancient vault in 
 the temple of Apollo, and that it raged with so much fury 
 as to sweep away a third part of the inhabitants of those 
 countries it visited." — Dr. Qiiinci/, on the Causes of Pesti- 
 lential Disease. 
 
 ^^ Upon an earthquake the earth sends forth noisome 
 vapours which infect the air ; so it was observed to be at 
 Hull in Yorkshire, by the Rev. Mr. Banks, of that place. 
 
07 
 
 any great pestilences, that stinking* mists, coming 
 from some unknown regions, and unusual vegeta- 
 tions have made their appearance in concert at these 
 times, what I ask is more natural than to imagine, 
 that they have been let loose during the general 
 convulsion ? It may be asked, what is to be said 
 about that revolution of the earth, when the great 
 Deluge spread over the whole face of the globe ? It 
 can only be replied, that this is a part of the scheme 
 of cosmogony into which we are not called upon to 
 enter. There are yet strenuous supporters of the 
 partial as well as total submersion of this planet, 
 but whether it be true that the vast torrents which 
 appear to have swept the surface uniformly in a 
 southern direction, were of a date coeval with the 
 deluge, and constituted an essential portion of the 
 phenomena, of which one was, that " the fountains 
 of the great deep were broken up," or whether they 
 were anterior to this catastrophe, will not at all inter- 
 fere with the conjecture of a very early formation 
 and propagation of the germs of pestilential diseases, 
 for the commotions of a deluge were less likely to 
 interfere with the vapours of the atmosphere, than 
 extensive volcanic and electric disturbances. More- 
 over, it is rather in favour of this theory, that the 
 
 after a small earthquake there in 1 703, it was a most sickly 
 time for a cousidcrable while afterwards, and the greatest 
 mortality that had been known for fifteen years." 
 
 Anonymous, 1769. 
 F 2 
 
\ 
 
 68 
 
 regions where the temperature and exhahitions 
 most nearly resemble those of the former condition 
 of the earthy are those in which pestilential disor- 
 ders most frequently arise^ and where their virulence 
 has always been most strong-ly marked. 
 
 After the various commotions which left the 
 giobe^ with its present physiog-nomy of mountains^ 
 plains^ valleys^ rivers^ lakes^ and oceans ; a new 
 Flora and Fauna appeared to adorn and animate 
 the scene of man's existence. Plants and animals 
 were created apparently in adaptation to the nume- 
 rous climes^ which the seasons in the various latitudes 
 or the elevations of the soil^ were prepared to render 
 fruitful and useful each in its ow-n sphere. Besides 
 this^ the plants of the &ame latitude^ in some in- 
 stanceS; differ materially from each other 3 in this 
 ease it seems that the soil has much to do with this 
 peculiarity^ for it is certain that the soil and the 
 contig'uous atmosphere^ have a close and intimate 
 relation ; the drought of the desert depends upon the 
 sand^ as humid atmosphere is connected with the 
 morass. To illustrate the tendency which vegetation 
 shews in appropriating" one locality more than ano- 
 ther^ I ma}?- quote the following : ^^ Some of the 
 volcanic masses of the ^olian or Lipari Islands^ 
 that have existed beyond the reach of history^ are still 
 without a blade of verdure , while others in various 
 parts^ of little more than two hundred years date^ 
 bear spontaneous vegetation^ and the same is seen 
 on two lavas of Etna near each other, for the one 
 
69 
 
 of I086 is still black and arid^ while that of 1636^ 
 is covered with oaks^ fruit trees^ and vines/^ 
 
 In comparing- the diffusion of plants^ and the 
 diffusion of diseases^ the different modes by which 
 this generally has been effected may be considered 
 under heads^ that the comparison may be more 
 readily traced. 
 
 First, seeds are diffused by the atmosphere, 
 either by the prevalence of certain currents^ which 
 are produced by known laws^ in which case^ no ^ 
 difBculty occurs in the explanations ] or in a more 
 imperceptible manner, as by those more uncertain 
 atmospheric currents of a partial nature, which, 
 thoug-h they seem to have laws governing them, are 
 not yet understood. 
 
 Second, seeds are transported by water across 
 oceans, &c. when they can be floated on any mate- ^ 
 rial by which they are preserved, as by wrecks and 
 masses of wood, which have been washed down the 
 rivers. 
 
 Third J they are conveyed by man to all parts of 
 the globe. 
 
 Fourth, a period of latency is observed to apply 
 to them, that is, they require certain essential con- 
 ditions before germination occurs ; so that even in .y 
 some localities, a plant may not have been known 
 to exist in a particular neighbourhood, but by a 
 train of circumstances, it may make its appearance, 
 and again be a centre of development. 
 
 1st. I shall not here wander into th(^ speculation, 
 
70 
 
 whether })hiiits had orig-inully one birth-pltiee^ as a 
 centre from which they spread by various agencies^ 
 as supposed by Linnseus^nor into any enquiry beyond 
 those facts^ which may fairly come within our own 
 comprehension^ and within our own means of de- 
 monstration. 
 
 Many seeds are provided with means adapting- 
 them for floating* in the atmosphere^ these are by 
 pappi^ or wing-lets and hairs^ but it cannot be doubted 
 that the ag-ency of atmospheric currents^ is produc- 
 ^ tive of considerable effects in the dispersion of 
 
 ^ lig-hter seeds^ such as those of mosses^ fung-i^ and 
 
 lichens — lichens have been discovered in Brittany^ 
 which are peculiar to Jamaica^ and Monsieur De 
 Candolle concludes^ that their seeds had been car- 
 ried thence by the south-westerly winds^ which 
 prevail during- a great part of the year on this 
 portion of the French coast. 
 
 But Humboldt's testimony on the subject of 
 winds is most satisfactory^ for he says^ ^^ Small 
 sing-ing- birds_, and even butterflies^ are found at sea^ 
 at g-reat distances from the coast (as I have several 
 times had opportunities of observing- in the Pacific)^ 
 being- carried there by the force of the wind^ w^hen 
 storms come off the land." It is g-enerally believed^ 
 from abundance of proofs^ that the trade winds^ 
 and other continuous currents^ are means by which 
 plants are conveyed from one country to another.* 
 
 * See Sharon Turner's Sacred History, text and notes, 
 vol. i. p. 161 & 162. 
 
 \ 
 
71 
 
 As to the partial curreiitSj Humboldt further 
 says^ ^^ The heated crust of the earth occasions an 
 ascending* vertical cui'rent of air by which light 
 bodies are borne upwards. M. Boussing-ault^ and 
 Don Mariano De Bivero^ in ascending* the summit 
 of the Silla^ one of the gneiss mountains of Caraccas, 
 saw in the middle of the day^ about noon^ whitish 
 shining bodies rise from the valley to the summit of 
 the mountain^ 5755 feet high^ and then sink down 
 towards the neighbouring sea coast. These move- 
 ments continued uninterruptedly for the space of an 
 hour. The whitish shining bodies proved to be small 
 agglomerations of straws^ or blades of gTass^ which 
 were recognized by Professor Kunth^ for a species 
 of vilfa^ a genus^ which together with agrostis^ is 
 very abundant in the provinces of Caraccas and 
 Cumana." 
 
 On the plague of locusts we read^ that ^^ the Lord 
 brought an east wind upon the land^ all that day 
 and all that night, and when it was morning the 
 east wind brought the locusts." 
 
 On the Black Death we read, " There were many 
 locusts which had been blown into the sea by a ^ 
 hurricane, and a dense and aAvful fog was seen in 
 the heavens, rising in the east, and descending upon 
 Italy.'' 
 
 Of the Plague of 542, Gibbon says, " The winds 
 might diffuse that subtle venom, but unless the 
 atmosphere be previously disposed for its reception, 
 the plague would soon expire in the cold or tem- 
 
 u^ 
 
72 
 
 per ate regions of the north. The disease alternately 
 lang'uished and revived^ but it was not till a 
 calamitous period of fifty-two years^ that mankind 
 recovered their healthy or the air resumed its pure 
 and salubrious quality/^ 
 
 In the history of the Sweating- Sickness^ of which 
 ^ there were Hye distinct visitations^ we find ample 
 
 allusions to the atmosphere^ and the mode in which 
 the disease was conveyed by this medium. 
 
 I quote ag-ain from Hecker : ^^ It seemed that 
 the banks of the Severn were \he focus of the malady j 
 and that from hence^ a true impestation of the 
 atmosphere^ was diffused in every direction. Whi- 
 thersoever the winds wafted the stinking* mists^ the 
 inhabitants became infested with the sweating* 
 sickness. These poisonous clouds of mists were 
 ^ observed moving from place to place, with the dis- 
 
 ease in their train^ affecting- one town after another^ 
 and morning- and evening* spreading- their nauseating- 
 insufferable stench. At g-reater distances^ these 
 clouds being- dispersed by the wind^ became g-ra- 
 dually attenuated; yet their dispersion set no 
 bounds to the pestilence^ and it was as if they had 
 imparted to the lower strata of the atmosphere, a 
 kind of ferment which went on engendering itself 
 even without the presence of the thick misty vapour, 
 and being- received into men's lung's^ produced the 
 frig-htful disease everywhere."* 
 
 * " Each seed includes a plant ; that plant, again, 
 Has other seeds, which other plants contain, 
 
73 
 
 Mr. K. B. Martin, liarbour-master of Riiius<rate,' 
 ill a communication to Lord Carlisle on the Cholera 
 of last autumn^ says^ "At midnight of the 31st 
 Aug-ust (1849); the Samson (steam-tug*) proceeded 
 to the Goodwin Sands^ where the crew were em- 
 plo3^ed under the Trinity ag-ent^ assisting- in work 
 carried on there by that corporation. While there, 
 at 3 A. M. 1st September, a hot humid haze^ with a 
 hog-like smelly passed over them ] and the gTeater 
 number of the men there employed instantly felt a 
 nausea. They were in two parties. One man at 
 work on the sand was oblig-ed to be carried to the 
 boat ) and before they reached the steam vessel at 
 anchor, the cramps and spasm had supervened upon 
 the vomiting's ; but here they found two of the party 
 on board similarly affected. Here then is a very 
 marked case without any known predisposing- local 
 cause. Doubtless it was atmospheric, and in the 
 hot blast of pestilence which passed over them.'' 
 
 Many more instances might be quoted, to shew 
 that the germs of disease, as well as of plants, are 
 borne on the wings of the wind from place to place 
 
 Those other plants have all their seeds ; and those 
 More plants, again_, successively enclose. 
 Thus ev'ry single berry that we find, 
 Has really in itself whole forests of its kind. 
 Empire and wealth one acorn may dispense. 
 By fleets to sail a thousand ages hence ; 
 Each myrtle-seed includes a thousand groves. 
 Where future bards may warble forth their loves." 
 
 U- 
 
74 
 
 ill one country^ and from one country to another^ 
 the distance being* no obstacle^ however g-reat that 
 may be.* " Dust and sands/^ says Sharon Turner^ 
 '^ heavier than many seeds^ are borne by the winds 
 and clouds for several hundred miles across the 
 atmosphere^ falling* on the earth and seas as they 
 pass along*/' " The clouds not only bring us occa- 
 sionally meteoric stones^ hail; and epidemics^ but also 
 veg*etable seeds/'f 
 
 2nd. The transportation of seeds of plants by 
 water requires very little notice ; every one is fami- 
 liar with the mode in which coral islands^ which 
 gTadually rise out of the sea^ become covered with 
 veg-etation. '' If new lands are formed^ the org*anic 
 forces are ever ready to cover the naked rock with 
 life. — Lichens form the first covering* of the barren 
 
 * On June 5th, 1849, a man and his son, a lad aged 
 14 years, left Noss to fish, and when five miles out at sea, 
 no vessel being in sight, they both simultaneously became 
 aware of a hot offensive stream of air passing over them. 
 It was so decided, that the crab pots were examined to 
 discover if it were from them, but it did not, and five 
 minutes after the father's attention was directed to the 
 boy, who was vomiting and purging/' — Dr. Roe on the 
 Cholera at Plymouth, Med, Gaz. Aug. 24:th, 1850. 
 
 t Linnaeus remarked that Erigeron Canadense was 
 introduced into gardens near Paris from North America. 
 The seeds had been carried by the wind, and this plant 
 was in the course of a century spread over all France, 
 Italy, Sicily and Belgium. 
 
75 
 
 rocks^ where afterwards lofty forest trees wave their 
 airy summits. The successive growth of mosses^ 
 g-rasses^ herbaceous plants and shrubs or bushes^ 
 occupies the hiterveniiig* period of long* but undeter- 
 mined duration." 
 
 The following" may be cited as an instance of the 
 transportation of disease by water. '^ Cyprus lost 
 almost all its inhabitants^ and ships without crews 
 were often seen in the Mediterranean^ or afterwards 
 in the North Sea^ driving* about^ and spreading the 
 plague wherever they went on shoreP* 
 
 It requires no arg-ument to enforce the conviction 
 that cottons^ woollens^ furs^ skins^ &c. will retain the 
 matter of infection for almost an indefinite period ; 
 instances of the kind have been already given \ it is 
 therefore easy to understand that portions of wrecks 
 and ship's g-oods would be a fi^equent thoug"h un- 
 suspected source of infection. Dr. Halley mentions 
 a case^ in which a bale of cotton was put on shore 
 at Bermuda b}' stealth ; it lay above a month with- 
 out prejudice^ where it was hid^ but when opened and 
 distributed among" the inhabitants^ it produced such 
 a contagion that the living scarce suflSced to bury 
 the dead. Dr. Walker found seeds dropt accidentally 
 into the sea in the West Indies cast ashore on the 
 Hebrides. He says, '^ the sea and rivers waft more 
 seed than sails." The waters of many rivers induce 
 diarrhoea and dysentery.f Well water also in many 
 
 * Hccker. 
 
 t This is found most generally to be the case where 
 
 ^ 
 
 U 
 
76 
 
 \ places has a similar effect^ especially if aii}^ surface 
 drainag-e happens to liiid its way into the well. 
 
 3rd. The part performed by man himself in the 
 communication of disease to his fellow creatures^ is 
 perhaps the most fruitful source of the extensive 
 spread of epidemic and contag-ious diseases. 
 
 In the time of Moses^ restrictions were laid on 
 those who had the plag-ue of the leprosy to avoid 
 contag-ion ; the dictum for one so affected was^ " he 
 shall dwell alone 3 without the camp shall his habi- 
 tation be."^ All the ancient authors believed in the 
 
 rivers flow through uncultivated tracts of country. The 
 Californian emigrants suffer much from diarrhoea and 
 dysentery, if they drink of the river and certain well 
 waters of that gold district. 
 
 * "Purification from leprosy. As this fearful disease 
 was contagious and hereditary to the third and fourth 
 generation, the separation of lepers from the camp and 
 congregation, and the destruction of infected houses and 
 clothes, was of the utmost importance to the preservation 
 of public health. 
 
 "Leprosy was of three kinds: 1st, Leprosy in man. 
 2nd, Leprosy in houses. 3rd, Leprosy in clothes. 
 
 " Contagious or malignant leprosy was of two kinds, viz. 
 
 " 1st. The white leprosy, or bright berat, which was the 
 most serious and obstinate form which leprosy assumes. 
 It exhibited itself as a bright white and spreading scale, on 
 an elevated base ; turning the hair white in patches, which 
 were continually spreading. 
 
 " 2nd. The black leprosy, or dusky berat, which was less 
 serious than the foregoing. It did not change the colour 
 
infections natnre of pestilential fevers^ and some 
 other diseases ; but^ according to Mr. Adams^ they 
 held that no specific virus wns the cause^ and merely 
 a contamination of the surrounding* air by effluvia 
 fi*om the sick. Thucydides^ Hippocrates, Procopius, 
 Galen, Plutarch, all recognized the property of 
 communicability from one individual to another of 
 the plague ; and Hecker, on the epidemics of the 
 middle ages, abounds with instances in support of 
 contagion. As regards small-pox and measles, 
 Rhazes observes particularly the connection that 
 exists between the condition of the air and the 
 severity or mildness of these diseases, remarking 
 that small-pox seldom happens to old men, except 
 in pestilential, putrid, and malig'nant constitutions 
 of the air in which this disease is usually prevalent. 
 The history of the introduction of Scarlet Fever, 
 Hooping Cough, Lues, and other diseases into 
 the various countries of the globe, is sufficiently 
 convinchig that men carr}^ about with them the l_^ 
 
 seeds of disease 3 that while these attach themselves 
 to the persons and clothing of those who introduce 
 them into new climes, and flourish independently of 
 cultivation, yet the exotics which they foster with 
 so much care, often disappoint their most sanguine 
 expectations j and these ^^ languishing in our hot- 
 
 of the hair, nor was there any depression in the dusky spot ; 
 but the patches were perpetually spreading, as in the white 
 leprosy." — Analysis and Summary of Old Testament His- 
 tory. Oxford. 
 
 \ 
 
78 
 
 houses cfin g-ive but a very foint idea of the majestic 
 veg-etation of the tropical zone." Art in this 
 procedure fails to accomplish here^ what nature but 
 too sadly^ under some circumstances^ effects most 
 readily. The germs of some diseases thoug-h of an 
 exotic character^ under cong-enial influences of vari- 
 
 \ ous kinds^ appear to flourish with native vigour : 
 
 is it not SO; also^ with some forms of veg-etation ? 
 The aloe^ a native of Mexico^ which lives^ but does 
 not thrive well^ or reproduce under ordinary circum- 
 stances in this country^ will occasionally send forth 
 a most luxuriant blossom^'* so rare is this^ that 
 some say it occurs every 50 or 100 years^ but no 
 law seems to be established on this pointy any more 
 than the statement that we may expect pestilential 
 diseases at certain intervals. But that there are 
 intervals of uncertain duration when the aloe will 
 blossom, when the grapes will ripen^ and a general 
 productiveness of exotics will occur^ is as certain as 
 
 \ that seasons will occur when contagion will be 
 
 rife^ and a most unusual multiplication of disease 
 prevail. This is not an imaginary or speculative 
 notion^ — all observers of seasons and diseases within 
 the last twenty years^ may fully verify the state- 
 ment. 
 
 In 1846; a large vine^ the black Hambro-grape^ 
 
 * The Mexican Aloe blows when nine years old, and 
 then dies. At least this is its usual course in the island 
 of Cuba. 
 
79 
 
 ripened its fruit out of doors^ and was as fine as 
 an}' g-reen-house production ; but during nine 3'ears 
 that the vine has been under my inspection^ this was 
 the only time I have witnessed such a result. 
 
 We are apt to attribute an abundant or scarce 
 iruit season to temperature alone^ but this is an 
 error— for we have before remarked^ that though 
 certain lands may be in the same degTee of latitude^ 
 the plants which thrive well on one land^ will not do so 
 on the other: infine^ that where reason and analog-y 
 would lead one to expect a particular form of veg-e- 
 tation^ a totally different Flora is presented to the 
 view. These facts are indeed suo-o^estive of new 
 and important deductions. Is it yet explained why 
 the town of Birming-ham should be free from 
 Cholera ? There is a larg-e manufacturing- popula- 
 tion^ a great number of poor^ the usual overcrowding* 
 of individuals in small chambers^ a considerable 
 amount of destitution and depravity ', irreg-ular 
 habits of living-^ and unwholesome diet^ and doubt- 
 less many parts of the town^ which on investig'ation 
 w^ould have yielded all the elements usually con- 
 sidered necessary for the localization of the disease : 
 but no — here was some repelling* cause^ some 
 opposing- ag-ent to the g-eneration and propagation 
 of the pestilential seeds. There are no known laws 
 by which inorg-anic matter could be supposed to 
 observe such a selection^ or such an antag-onism. 
 Electricity^ mag-netism^ ozone^ g-ases^ exhibit no such 
 elective properties that here they will destro}'^ and 
 
 L 
 
\ 
 
 80 
 
 there the}^ will spare y that thej^ con almost depopu- 
 late small ^'illag^es^ and scarcely find a victim in 
 Birming-ham and Bath. But if we suppose a 
 living-^ and multiplying* matter as the cause of 
 disease^ many local causes ma}^ conspire to arrest 
 the development of the g-erms^ or perhaps^ even 
 utterly destroy them. 
 
 4th. As to the time of latency^ facts crowd 
 upon us indefinitely^ as elements of comparison 
 between veg-etation g-enerally^ and disease in its 
 early stag-es and history. The seeds of plants are 
 extraordinarily^ tenacious of life. What a m^^sterious 
 arrang-ement of the ultimate particles of matter 
 must there be^ by which the vital force remains 
 apparently inactive for many years^ and yet when 
 the conditions arise favourable to its manifestation^ 
 as it were by an extraordinary fiat^ life appears. 
 
 Previous to the year 1715; no broom g-rew in 
 the King*'s Park^ at. Stirling- , but in that year a 
 camp was formed there^ and the surface of the 
 ground consequently was broken in many places. 
 Wherever it was broken^ broom sprang up. The 
 plant was subsequently destroyed; but in 1745 a 
 similar growth appeared after the ground had been 
 again broken for a like purpose. Some time after- 
 wards the park was ploughed up^ and the broom 
 became generally spread over it. ^^ In several 
 places in the neighbourhood of Edinburgh/' says 
 Professor Graham^ ^^ the breaking of the surface 
 produces an abundant crop of Fumaria parviflora^ 
 
81 
 
 although the same plant had never before^ been 
 observed in the neighbourhood. It is impossible to 
 say the lapse of time since these were buried^ before 
 they were ag*ain excited to the performance of all 
 their vital functions." Dr. Graham also gives 
 another proof of the vital force existing in seeds. 
 " To the westward of Stirling there is a large peat 
 bog, a great part of which has been flooded away 
 by raising water from the River Teith, and dis- 
 charging it into the Forth^— the under soil of clay 
 being then cultivated. The clergyman of the 
 parish standing* by while the workmen were forming 
 a ditch in this clay, which had been covered with 
 fourteen feet of peat earth, saw some seeds in the 
 clay which was thrown out of the ditch y he took 
 some of them up and sowed them : they germinated 
 and produced a crop of Chrysanthemum septum. 
 What a period of years must have elapsed while the- 
 seeds were getting their covering of clay, and 
 while this clay became buried under fourteen feet of 
 peat earth !"* 
 
 * " Ground that has not been disturbed for some hun- 
 dred years,, on being ploughed, has frequently surprised the 
 cultivator by the appearance of plants which he never 
 sowed, and often which were then unknown to the country. 
 The principle has been ascertained to be capable of exist- 
 ing in this latent state for above '2000 years, unextinguished, 
 and springing again into 'active vegetation, as soon as 
 planted in a congenial soil. 
 
 '* In boring for water near Kingston on Thames, some 
 
82 
 
 What limit can there be to the dispersion of seeds 
 when their vital properties may remain so long- 
 unimpaired? The seeds of which we have been 
 speaking" were^ no doubt many of them^ washed 
 away with the waters of the Teith^ and carried by 
 the stream into the Forth ; and who shall then mark 
 their destination j for we have seen that by such 
 means the most distant lands are supplied with 
 veg-etation j for whence come the plants which cover 
 the Goral Islands^ unless by the air and the water, 
 and that both contribute, has been incontestably 
 proved. Dr. Lindley states that melon seeds have 
 been known to grow when forty-one years old ) 
 maize thirty years, rye forty years, the sensitive 
 plant sixty years, kidney-beans a hundred years. 
 But seeds in g^eneral have an indefinite period, ap- 
 parently, at which they can retain their power of 
 germination ; for many of the seeds which had been 
 kept in the herbarium of Tournefort for more than 
 a century, were found to have preserved their 
 fertility. 
 
 It has now to be shewn that the g'erms of disease 
 also retain their vital powers in a state of dormancy 
 during- a lengthened period. 
 
 earth was brougbt up from a depth of 360 feet_, and though 
 carefully covered with a hand-glass to prevent the 
 possibility of other seeds being deposited on it, was yet in 
 a short time covered with vegetation. 
 
 "Turner says, from the depth, these seeds must have 
 been of the diluvian age/' — Jesse's Gleanings. 
 
8;3 
 
 Mead has veiy judieioiisl}^ observed^ ^^to breed a 
 distemper^ and to give force to it Avhen bred, are 
 two different thing-s." He further remarks^ that 
 the seeds of the Pkigue ma}^ confine themselves 
 to a house or two duiing- a hard frosty winter^ and 
 be preserved^ and ag*ain put forth their mali^ant 
 quality as soon as the warmth of the spring* gives 
 them force. It is certainly very remarkable that 
 the Plag-ue of London^ which commenced at the 
 latter end of the year 1664^ should ^Hie asleep/' as 
 Mead says^ from Christmas to the middle of 
 February^ and then break out in the same parish. 
 
 It has been also known that an infected bed laid 
 by for seven years had done infinite mischief on 
 being* ag^ain broug-ht into use. Indeed^ it is quite 
 uncertain for how long* a period woollen^ fur^ linen, 
 cotton, and other articles may retain infectious 
 matter in a dormant state. It has be^n supposed 
 by some that in closely packed bed and body clothes 
 a multiplication of the g-erms may and does take 
 place, nor do I see any reason why this should not 
 be the case, for these articles contain within their 
 structure the effluvia of the animal body, and they 
 may possibly there find sufficient nutriment for 
 their development. Nees von Esenbeck believed 
 that some of the minute Cryptog'amia were re-pro- 
 duced in the air, we are not therefore exceeding* 
 philosophical conjecture when we imag*ine a basis 
 and substratum, though an unusual one, for the 
 g*erms of veg-etation. Exclusion from air and lig'ht, 
 
 G 2 
 
84 
 
 however, as would be the case in packed-up clothes^ 
 \ would a priori give a better colour to the conjec- 
 ture^ as these are the usual conditions necessary for 
 the growth of seeds. 
 
 Small Pox and Cow Pox matter^ which are now 
 proved to be the same virus^ the former modified by 
 having" been through a process of growth and 
 maturation in the cow^ are both remarkable for 
 exhibiting their active properties after having lain 
 dormant for a considerable time. And each^ though 
 so closely allied^ retaining its specific properties. 
 
 This peculiarity in the history of Small Pox 
 virus suggests a comparison with some phenomena 
 of vegetation^ viz, that of grafting or budding. The 
 lower Cryptogamia in their fructifications resemble 
 rather multiplication by buds than by seeds. M. 
 Moyen's idea is that every spore or little globule^ 
 independently of its neighbouring one^ lives^ absorbs^ 
 assimilates^ grows^ and re-produces on its own 
 account ) this is certainly the characteristic of the 
 Torula and the Uredo^ and doubtless is so of many 
 other of the Cryptogamia^ the Protococcus nivalis is 
 another instance. Other modes of cultivation pro- 
 duce also great varieties of results of an unexpected 
 kind. 
 
 Would any one^ says Dr. Walker^ imagine that 
 
 cabbage^ cauliflower^ savoy^ kale^ brocoli^ and turnip - 
 
 ^ rooted cabbage^ were the same species ? yet nothing 
 
 is more certain than that they are only varieties 
 
 produced by the cultivation of the Brassica oleracea, 
 
85 
 
 a plant which grows wild on the sea-shores of 
 Europe. 
 
 These varieties in vegetables have now become 
 permanent^ and thoug-h it is supposed that each is 
 liable to return to its original condition^ I am not 
 yet certain that such is the tendency. A deteriora- 
 tion is not unlikely to ensue in the course of time, 
 because the propagation by seeds must necessarily 
 very much approach the system of intermarriage, 
 on which Mr. Walker has so ably written and 
 clearly shewn that as a result we may invariably 
 expect a deterioration of the species. Dr. Darwin 
 has also poetically described what his experience 
 taught him, 
 
 " So grafted trees with shadowy summits rise^ 
 Spread their fair blossoms and perfume the skies. 
 Till cankei^ taints the vegetable blood, 
 Mines round the bark and feeds upon the wood ; 
 So years successive from perennial roots, 
 The wire or bulb with lessened vigour shoots, 
 Till curled leaves or barren flowers betray 
 A waning Uneage verging to decay ; 
 Or till amended by connubial powers. 
 Rise seedling progenies from sexual flowers." 
 
 The minute nature of the germs of disease pre- 
 clude all possibility of their being submitted, as far 
 as we know at present, to the inspection of the 
 ])hysiologist, but we may infer many facts from 
 results. In the same way, though with humbler 
 
86 
 
 ideas^ as Cuvier could build up an animal from a 
 sing-le boiie^ can we by a combination of facts infer 
 the existence of living* being's and conjecture their 
 forms. '^ The re-production or g-eneration of living* 
 \^ org-anized bodies is the g*reat criterion or character- 
 istic which disting-uishes animation from mechanism/' 
 We find the virus of Small Pox^ according* to Mr. 
 Ceely's experiments^ developing* itself as a consti- 
 tutional disease upon the cow^ and becoming 
 modified into a form known as the Cow Pox 3 this 
 resembles the process of cultivation by which a 
 species is converted into a variety^ this variety 
 remains for a certain time persistent ; the time is not 
 yet known^ but it is known that by degrees^ as 
 stated above^ a deterioration occurs^ and fertility 
 becomes impaired^ ^^ a waning* lineag*e verg'ing* to 
 decay/' and this has been observed as a feature in 
 the result of vaccination. I believe Dr. Greg*ory 
 A\as one of the first to notice this fact^ and deemed 
 it necessary to obtain fresh lymph from the cow ; 
 this has been done^ and it is not improbable^ if the 
 analog*y we have drawn be correct^ that the slowly 
 spreading scepticism regarding vaccination may be 
 arrested in its progress. If we can explain the 
 deterioration of cow pox virus on this principle we 
 have a hold at once upon the public^ and can assure 
 them that the efficacy of the proceeding is as certain 
 as in the time of Jenner. The people^ I contend^ 
 have a right to demand of us the reason why 
 vaccination is not so efficacious as formerlv, and I 
 
87 
 
 affirm as unhesitatiiig'ly that we are bound to give 
 the subject our most earnest attention.* 
 
 Now concerning- the re-production of Cow Pox 
 matter^ and assuming- it to resemble that of the 
 lower Cryptog-amia^ we can easily understand how 
 degeneration in a course of years should ensue^ for 
 we find that though the Small Pox is a constitu- 
 tional disease^ that produced by vaccine lymph is a 
 local affection^ so that it bears the relation that 
 grafting does to vegetation, and it is not improbable 
 that such a modification takes place in the germs 
 by passing through or becoming generated in the 
 blood of the cow^ that they entirely lose their 
 original and characteristic form of reproduction : 
 the seeds of the disease were originally capable of 
 vegetating, if I may be allowed to use the term^ by 
 diffusion through the atmosphere ; they now^ how- 
 ever, have lost that property^ and require to be 
 grafted to exhibit any manifestation of vitality. 
 
 How often will the seeds of a cultivated fi'uit 
 grow ? If you bud it upon another plant^ you ob- 
 tain a being exactly like the parent^ but this^ as we 
 have seen^ deteriorates in a course of years^ we 
 have also seen that the virus deteriorates j but not 
 to stretch this point to an unseemly leng-th^ I 
 cannot avoid expressing my conviction^ that these 
 are elements of comparison^ possessing an interest 
 and a practical utility of no small value. 
 
 * Hamilton's History of Medicine, vol. ii. p. 276, uotc. 
 
\ 
 
 88 
 
 I have before said^ that the reproduction in the 
 Cryptogam ia^ rather resembles budding' than seed- 
 ing*. If we observe the Torula^ or take the process 
 of all formation^ g-enerally it will be found to accord 
 more exactly with the budding- than the seeding* 
 process^ and this peculiarity is not confined to veg-e- 
 tation^ it is also a marked feature in the reproduction 
 of infusoria^ spong-es^ polypes^ &c. 
 
 " New buds surround the microscopic plant/' 
 
 The reproduction of plants and animals appears 
 to be of two kinds^ solitary and sexual ; the former 
 occurs in the formation of the buds of trees^ and 
 the bulbs of tulips. 
 
 The microscopic productions of spontaneous 
 vitality propag-ate by solitary g*eneration only. 
 
 We have but reached the threshold of this vast 
 and interesting* subject^ the experiments which sug*- 
 g-est themselves to the mind while reflecting* upon 
 it^ would alone occupy a whole life of leisure^ and 
 I can but feel how forcibly Mr. SewelFs words 
 apply to us : " The g-rand field of investigation lies 
 immediately before us^ we are tramj)ling* every 
 hour upon things which to the ignorant seem 
 nothing but dirt^ but to the curious are precious as 
 gold.^' 
 
 It is difficulty perhaps^ to bring many instances^ 
 in which the germs of disease have lain dormant for 
 a lengthened period^ because many may take excep- 
 tion to them^ from the fact^ that sporadic cases of 
 
89 
 
 most epidemic and infectious diseases^ are rarely 
 absent from any country in which those diseases 
 have become indigenous, and these cases may be 
 said to be the foci whence orig-inates the epidemic 
 constitution of the air; this, however, would not \y 
 invalidate the supposition, because one of two in- 
 ferences must be drawn, either that the germs of 
 disease always exist in a dormant state, requiring" 
 circumstances and conditions only for their develop- 
 ment, or that the g*erms are imported from some 
 distant locality, where the disease has occurred, 
 and finding a nidus there, grow and multiply.* 
 Whichever notion we take, however, matters very 
 little to the fact of the dormancy of the germs, for 
 in both, a certain period elapses between their 
 transmission and their propagation. It may fairly 
 be presumed, that sometimes one method may apply 
 
 * "\Miat I wish you to remark is this, that while 
 almost all men are prone to take the disorder, large por- 
 tions of the world have remained for centuries entirely- 
 exempt from it, until at length it was imported, and that 
 then it infallibly diffused and established itself in those 
 parts." — Dr, Watson on the Principles and Practice of 
 Physic. 
 
 Dr. R. WilUams says, " The seeds of intermittent fever 
 lay dormant for months, it was not at all uncommon for 
 cases of intermittent fever to be brought into the hospital 
 eight or ten months after the patients had subjected them- 
 selves to the influence of paludal or marsh effluvia.'^ 
 
^ 
 
 90 
 
 and sometimes the other^ perhaps both during* 
 g-eneral epidemic conditions of the atmosphere. 
 
 The Oidium vitis attacked the vines partially last 
 year^ and I believe generally spared other forms of 
 veg-etation 3 but this year in my vicinity^ cucumbers^ 
 melons^ and vegetable marrows^ are all suffering 
 more or less under the disease.* How shall we say^ 
 whether are the seeds of last year the cause of the 
 g-eneral diffusion at the present time^ or were there 
 a sufficient number of old and dormant seeds^ uni- 
 versally diffused^ and only waiting- opportunities for 
 multiplying- themselves ? We are here on the horns of 
 a dilemma ; and spontaneous g-eneration^ from which 
 one naturally shrinks^ can alone extricate us^ if we 
 do not admit diffusion and dormancy. I think I 
 may^ without undue assumption, affirm that a 
 period ^f latency of indefinite duration, applies as 
 cogently to the germs of disease as to those of 
 plants. 
 
 There is yet one other point in connection with 
 this subject, and that is the apparent extinction of 
 some diseases, at any rate their non-appearance in 
 certain localities, which had been at one time con- 
 genial to them, and in which they flourished. We 
 have seen, in illustrating the dormancy of seeds, 
 that the broom must have been a common plant at 
 
 * I have observed in the hot-houses_, that many of the 
 exotic plants, which are in company with the diseased 
 vines_, have been attacked, while others again have been 
 entirely free. 
 
91 
 
 some considerable period back^ in the King's Park 
 at Stirling-^ or on that site. 
 
 Then ag*ain^ the appearance of Fumaria par- 
 viflora in the vicinity of Edinburg-h^ in several 
 places where the ground is broken^ is sufficiently 
 convincing" that this plant must once have been a 
 common form of veg^etation there ; and as it had 
 never before been observed in the neighbourhood^ 
 there must have been a combination of peculiar 
 circumstances capable of rendering* germination 
 impossible^ otherwise a continued multiplication^ as 
 in other forms of vegetation^ would have followed 
 of necessity. 
 
 But besides these instances^ how many are 
 passing under our own eyes of the disappearance of 
 plants under the influence of cultivation^ and the 
 generation of the noxious fumes arising from 
 different and innumerable manufactories. In the U^ 
 vicinity of large cities and manufacturing towns^ 
 how rarely do we see healthy vegetation ', shrubs 
 and animals drag on a sickly and almost unprolific 
 existence^ and their term of natural hfe is much 
 shortened. 
 
 And if we compare diseases with this peculiar 
 feature of vegetation^ how very close do we find 
 the analogies. The Sweating Sickness which ap- 
 peared in the latter part of the fifteenth century, L^ 
 and at certain intervals multiplied and extended 
 itself at first only in this country, but ultimately 
 more or less over the continent of Europe^ has 
 
92 
 
 never since the year 1551 shewn any symptom of 
 productiveness^ indeed for all we know the disease 
 may be extinct ; on the other hand^ it is impossible 
 to say whether or not circumstances may arise^ 
 under which it may commence ag-ain^ to put forth 
 its energ-ies and ag-ain desolate the land.* 
 
 Since 1665^ the Bubo-plag'ue has not found a 
 cong-enial soil in this country^ or if the seeds be 
 here^ which is more than probable^ the necessary 
 conditions to excite them to activity do not exist. 
 
 It cannot be imagined that with all the merchan- 
 dize which comes into this country from the 
 Mediterranean^ but that an abundance of the g-erms 
 of the disease are annually broug'ht into our ports^ 
 and disseminated throughout the land. The law by 
 J which we have seen that they possess a power of 
 vitality and reproduction^ holds now as it did in for- 
 mer times ; — the properties of matter never alter^ 
 but the conditions under which they exist may be so 
 modified^ as to influence their properties^ and the 
 usual course of their operations. It is therefore to 
 
 \ 
 
 * By causes of the greatest variety plants may become 
 extinct for a time. It is not very easy to trace them, but 
 one fact may be mentioned in proof of the statement. 
 Dr. Prichard states that vast forests are destroyed either 
 for the purpose of tillage or accidentally by conflagrations. 
 " The same trees do not reappear in the same spots, but 
 they have successors, which seem regularly to take their 
 place. Thus the pine forests of North America when 
 burnt, afford room to forests of oak trees." 
 
93 
 
 an alteration or modification of conditions that we 
 are to look for the exemption^ during- the last two 
 centuries^ fi*om an invasion of the Plague. To say 
 what those conditions ma}?" be in their totality 
 is difficulty perhaps impossible. We may g-eneralize 
 on the subject^ and imag-ine the reason discovered, 
 but all those causes which were said to have con- 
 spired to favour the spread and contamination with 
 Plag-ue^ were as distinctly specified and attributed^ 
 as the cause of our late infliction with Epidemic 
 Cholera. Why then did we have the Cholera and 
 not the Plag'ue ? To what particular element was 
 it — in the mode of living*^ of destitution^ of filth 
 and want of drainage— can it be ascribed that we 
 suffer under one disease, and not under the other ? 
 
 We have made some few observations and com- 
 parisons on the mode of dispersion of plants and 
 diseases^— but there is yet one more point which 
 invites notice. Not only do seasons vary in their 
 effects on vegetation in a remarkable and unexplained 
 manner^ but there are many localities to which some 
 special form of veg-etation attaches^ and which 
 appear to have a power of exclusion of other forms ; 
 and as yet I have not been able to trace the 
 connexion^ nor can I discover it in the writing's of 
 botanists and travellers^ who would be most likely 
 to have sought an explanation of so interesting- and 
 curious a fact. Dr. Prichard has on this subject 
 some very apposite illustrations. " Still further 
 southward, the austral temperated zone completely 
 
94 
 
 chang-es the physiog-nomy of veg-etatidn^ and the 
 Isle of Norfolk has^ in common with New Holland^ 
 the Auracania found also in the harbour of Balade^ 
 and with New Zealand^ the Phormium tenax. It is 
 however remarkable^ that this vast island^ composed 
 of two lands^ separated by a channel^ thoug-h so 
 near New Holland^ and lyings under the same lati- 
 tude^ differs from it so completely_, that they display 
 no resemblance in their veg-etation. Yet New 
 Zealand^ so rich in g-enera peculiar to its soil^ and 
 little kno wn^ has some Indian plants : such as Pepper^ 
 the Olea^ and a reniform Fern/ which is said to 
 exist in the Isle of Maurice." 
 
 I must quote one more passag*e from Dr. 
 Prichard's excellent work. ^^ We have one instance 
 of an island at no g'reat distance from a continent^ 
 having" a peculiar veg-etation. Mr. E. Brown has 
 remarked^ that there is not even a sing-le indig-enous 
 species characterising" the veg"etation of St. Helena^ 
 that has been found either on the banks of the 
 Cong"o^ or on any other part of the Western coast 
 of Africa. Does the diversity of marine and atmos- 
 pheric currents more completely separate this 
 island from the continent^ than its situation would 
 imply ', or are the nature of soil and other local 
 circumstances^ the cause of so marked a diversity? 
 The last supposition seems the most probable j 
 because not only the species of plants^ but likewise 
 the genera in St. Helena, are different from those of 
 the African coast." 
 
95 
 
 We are not without instances of diseases^ observing- 
 this peculiarity which attaches to plants ; but their 
 specific characters have hardly been sufficiently con- 
 sidered in reference to climate and situation^ together 
 with diet and local influences^ to afford us accurate 
 data for comparison. It has^ however^ been remarked^ 
 in every country where Epidemics have prevailed, 
 that some districts or tracts of country, though sup- 
 posed to possess all the qualities favourable to the 
 development of the diseases, have nevertheless been 
 entirely or nearly fi'ee from them. The following* pas- 
 sage on the course of the Cholera gives an example of 
 this peculiarity. ^^Whenever the malady deviated, so 
 to speak, from its normal direction, and passed 
 towards the west, it seemed incapable of propagating i^ 
 itself; and died away spontaneously ^ even in places 
 which appeared to he well Jit ted for its reception, — 
 The rich fertile and densely peopled countries to the 
 right of the Dneiper, enjoyed an equal freedom 
 from attack, which can only be explained by the 
 fact that they were situated heyond the line of the 
 disease,^' With this I close the subject of the dif- 
 fusion of plants and diseases, though it would 
 require a volume of itself, to record all that has 
 been noticed. I have endeavoui'ed to select such 
 instances as shall mark distinctly the features which 
 point to comparison without overloading the enquiry. 
 
\ 
 
 90 
 
 SECTION IV. 
 
 THE RELATION BETWEEN EPIDEMIC AND ENDEMIC 
 DISEASES. 
 
 Epidemic diseases^ which multiply their g-erms in 
 any climate^ and under apparently the most varying* 
 conditions of temperature and hyg-rometric and 
 electrical states of atmosphere^ offer many points of 
 contrast with Endemic affections^ and many of rela- 
 tionship. The latter are traceable to a certain 
 extent^ to g"eolog*ical and g-eog"raphical positions of 
 the localities where they are observed to prevail^ 
 in combination with atmospheric vicissitudes and 
 peculiarities^ as well as to extent of cultivation of the 
 soil: it has been remarked that the sickly island 
 (as it is called) of St. Lucia has certain salubrious 
 parts^ but these are where sulphur abounds \ this 
 g'eolog'ical peculiarity has been deemed sufficient to 
 account for the absence of endemic affections in 
 these partS; and with much force of reason \ for in 
 the neighbourhoods where sulphur or sulphurous 
 acid^ a compound of sulphur^ is an element prevalent 
 in the soil or atmosphere^ veg*etation and the ag*ue 
 disappear tog'ether. 
 
 Now ag'ue^ and other endemic fevers^ doubtless 
 
 o orig-inate from some allied^ if not identical cause j 
 
 for the localities in which they appear have so many 
 
97 
 
 features in common^ that we are constrained to 
 acknowledge that endemic fevers have some rela- 
 tions and analogies^ though not yet unravelled. 
 
 Geographical situation, together with certain 
 vegetation, particularly of grounds which grow rice, 
 is one remarkable for the production of endemic 
 affections. But the soil which generates or gives 
 force to the contaminating matter, is not alone the 
 part where human beings feel its influence most 
 severely. A low marshy ground, prolific of malaria, 
 may be comparatively free; while some neigh- 
 bouring elevated land, to which prevailing currents 
 of air waft the volatile elements of disease, may be 
 desolated by their virulent and concentrated action. 
 " Malaria may be conveyed a considerable distance 
 from its source, and he condensed in the exhaled 
 vapour, when attracted by hills or acclivities in the 
 vicinity, and when there are no high trees or woods 
 to confine it, or to intercept it in its passage." 
 
 The inhabitants of the city of Abydos were at 
 one time subject to disease, arising from malaria, 
 generated in . some neighbouring marshes ; by 
 draining these marshes, which suspended the growth 
 of rank vegetation, the city became healthy. 
 
 Rome is in like manner even now subject to 
 fevers, having a similar origin. Sir James Clark 
 says, " Among the more prevalent diseases of Eome, 
 malaria fevers are the most remarkable, and claim 
 our first notice." He considers the fevers to be of 
 exactly the same nature as those of Lincolnshire 
 
 H 
 
 L^ 
 
\ 
 
 98 
 
 and Essex in this country^ of Holland^ and certain 
 districts over the g-reater part of the globe. To the 
 climate^ the season^ or the concentration of the cause 
 of these fevers^ he attributes their varieties. It is 
 the same disease^ he says, whether from the swamps 
 of Walcheren^ or the pestilential shores of Africa. 
 
 From July to October the inhabitants of Eome 
 are most subject to these affections. 
 
 Sir James Clark further says : '^ It may be 
 stated as a general rule^ that houses in confined 
 shaded situations^ with damp courts or gardens^ or 
 standing" water close to them^ are unhealthy in every 
 climate and season; but especially in a country 
 subject to intermittent fevers^ and during- summer 
 and autumn. The exemption of the central parts of 
 a larg-e town from these fevers^ is explained by the 
 dryness of the atmosphere^ and by the comparative 
 equality of temperature which prevails there." 
 
 In this respect there is a marked difference be- 
 tween an epidemic and an endemic affection; for 
 when an epidemic disease attacks a city or town we 
 do not discover that the central parts are more 
 exempt than others ; indeed^ it is rather the con- 
 trary; for the most crowded parts of towns and 
 cities are those^ if not exactly in the centre^ which 
 would be comprised in a space nearer to the centre 
 than the circumference ; and it has been in those 
 parts g-enerally where the epidemic influences seem 
 to have exercised the most potent sway. One would 
 more naturally suppose^ that a city surrounded by 
 
u- 
 
 99 
 
 paludal miasm^ and not itself being- capable of gene- 
 rating- the poison, should be more affected at the 
 circumference, from the simple fact that the paludal 
 g-erms, which rise in the air, are suspended in the 
 fog's and dews of the atmosphere. These, unless 
 widely dispersed by the winds, would remain w ithin 
 a comparative^ confined space j and those situations 
 nearest to them would be most subject to their in- 
 fluence. Besides, it has been shewn, that a small 
 wood or hill, or even a wall, has been sufficient to 
 cut off or obstruct the paludal miasm. 
 
 Without enumerating all the known endemic 
 diseases, two or three may be alluded to for our pre- 
 sent purpose \ viz. that of shewing- that endemic 
 and epidemic diseases have a similar orig-in.* 
 
 It is well known that under certain favouring- 
 conditions an endemic may become a malig-nant and 
 pestilential disease; that Yellow Fever, which is 
 always endemic in the west. Cholera in the east, and 
 the Plague in the south of Europe and north of 
 Africa, every few years takes on an epidemic form, 
 and desolates considerable tracts of country.* 
 
 The Pestilence which rag-ed in the summer and 
 autumn of 1804 in Spain, commenced at Malaga, 
 and remained for a considerable time confined to its 
 
 * Hecker says of ChaUn de Vinario, that " he asserted 
 boldly and with truth, that all epidemic diseases might /, 
 become contayious, and all fevers epidemic, — which atten- 
 tive observers of all subsequent ages have confirmed.'^ 
 
 P. 60. 
 H 2 
 
100 
 
 boundaries^ in consequence of the measures of pre- 
 caution that were used^ in preventing" all communi- 
 cation between the inhabitants of the infected city 
 and those living* in the surrounding* country. It 
 Avas only in consequence of persons escaping* throug*h 
 the cordon^ and passing* into the interior of the 
 country^ that the disease spread^ and extended its 
 ravag*es to distant places. 
 
 It appears to be quite clear^ that this disease may 
 properly be considered in the first instance of en- 
 demic origin ; but the tendencies^ atmospheric and 
 otherwise^ were such as to favour its multiplication 
 in other districts than that in which it first came 
 into active existence. From this we may infer^ that 
 the seeds of the disease were dormant^ and only 
 became roused into vital activity by fortuitous cir- 
 cumstances. Dr. Rush states^ that the endemic 
 disorders of Pennsylvania were con^erted^ by clearing* 
 the soil^ to bilious and malig*nant remittents, and to 
 destructive epidemics. Dr. Copland says^ it has 
 been observed^ especially in warm climates^ and in 
 hot seasons in temperate countries^ that when the 
 air has been long* undisturbed by hig-h winds and 
 thunder-storms^ and at the same time hot and moist^ 
 endemic diseases have assumed a very severe and 
 even epidemic character. 
 
 Dr. Robertson also confirms this view. ^'Endemic 
 diseases^ in cases of neg-lect and preposterous ma- 
 nagement^ are found to become more malig-nant 
 even in the most temperate climates , and to g*ene- 
 
101 
 
 rate a matter in their course^ capable of producing* 
 a particular disease in any circumstances. Indeed 
 the origin of every contagious fever unattended with 
 eruptions^ with the exception of Plag-ue^ must com- 
 mence in this way.'^ Why Dr. Eobertson should 
 except eruptive Fevers and Plague I cannot under- 
 stand^ for they must have had a commencement ; 
 and their many points of similarity indicate^ if not an 
 identical^ an analogous source to other endemic 
 fevers. 
 
 It will doubtless be generally acknowledged that 
 endemic and epidemic diseases depend upon some 
 unknowTi agents^ having their source in malarious 
 districts^ and being capable of assuming either a 
 contagious or non-contagious character^ according 
 to circumstances. 
 
 If, therefore, we find that under any conditions an 
 endemic affection becomes capable of being propa- 
 gated by contagion, the same law will hold with 
 regard to it as to the Plague ; that the power of re- 
 production in this matter is evidence of life, according 
 to the doctrine laid down in the earlier part of this 
 work. But whether or not infection be admitted, a 
 matter generated in a malarious district, if confined 
 in its effects to that district alone, would not neces- 
 sarily imply an inorganic nature of the poison ; for 
 it is difficult to understand how inorganic poison, 
 prevailing generally over a certain tract of country, 
 could select particular individuals for its victims. 
 If chloroform, chlorine, carbonic acid, sulphuretted 
 hydrogen, or even spores of poisonous fungi, (as 
 
102 
 
 supposed by Mitchell^ which^ as he reg-ards their 
 effects^ would act in a similar manner to inorg-anic 
 compounds) were the ag-ents^ all persons would 
 suffer more or less^ and the majority be similarly 
 affected. We do not find that uniformity of symp- 
 toms^ which attend upon the exhibition of poisons 
 in the ordinary acceptation of the term^ poisoning. 
 This subject shall be more particularly considered^ 
 when treating* of the influence of org-anic g'erms on 
 animals and plants. 
 
 The history of the Eclair steamer is particularly 
 interesting-^ as shewing- the extraordinary tenacity 
 with which the g-erms of disease attach themselves 
 to vessels^ which we may call floating houses. 
 
 The crew of the Eclair contracted Yellow Fever 
 on the coast of Africa^ and a number of them died. 
 The remainder^ sick and well^ landed at Bona Vista, 
 one of the Cape de Verde Islands, and the vessel 
 underwent a process of washing-, whitewashing-, and 
 fumig-ating-. Nevertheless, on the return of the ship's 
 company, the disease broke out ag-ain with equal 
 mtensity, and the vessel was ordered home. Sixty- 
 five out of 146 officers and men, who composed the 
 crew, died of the disease before reaching- Portsmouth, 
 and twenty -three were sick at the time of arrival. 
 
 Eig-ht days after the Eclair left Bona Vista, a 
 Portug-uese soldier who had mixed with her crew 
 died in the fort which had been occupied by them. 
 Other soldiers then fell sick, and the fort was aban- 
 doned. The fever still spread. 
 
 From the 20th September, when the first soldier 
 
103 
 
 was attacked^ to the first week in December^ the 
 fever continued to rage^ and at that period it had 
 found its way into almost all the country villages. 
 The fever was believed to be the genuine black vomit 
 fever ; it proved contagious almost without excep- 
 tion to the nurses of the sick. 
 
 This is an abstract of Mr. RendelFs letter to Lord 
 Aberdeen^ Mr. Rendell being British Consul at 
 Bona Vista. 
 
 Now at the time the fever broke out in the island 
 the weather was extraordinarily hot^ and much rain 
 had fallen^ and the town itself was badly drained 
 and in a filthy state ; can it be imagined then that 
 the seeds of a disease liable to assume a pestilential 
 character should lie dormant or be annihilated under 
 circumstances the most favourable for their develop- 
 ment^ especially when we know that endemic diseases 
 may assume a malignant character ? 
 
 This is just one of many cases which confirm our 
 opinion in this respect, that plants and diseases are 
 not long in making their appearance where the soil 
 and atmosphere are congenial. 
 
 The tenacity with which the disease attached 
 itself to the Eclair is sufiiciently explained in the 
 absence of due ventilation ; in fact^ that in the first 
 instance there was no ventilation at all in the hold 
 of the ship. This also the more readily affords a 
 clue to the disaster through all its stages, first in the 
 contraction of the disease as an endemical affection 
 in the vessel ; secondly, in the multiplication of the 
 
104 
 
 g-erms in the damp ill-ventilated hold^ in a warm 
 climate ; and thirdly^ the persistence and entire 
 localization of the disease to the vessel when it 
 arrived in the climate of the British shores ; while^ 
 fourth and lastly^ in the unusually hot and damp 
 island of Bona Vista^ the seeds of the disease were 
 sown^ and^ as we mig-ht expect^ multiplied indefi- 
 nitely. 
 
 The consecutive attacks of the crew of the Eclair 
 shew that here a noxious gas or a vaporized inor- 
 ganic poison could not have been the cause of the 
 disease^ for as I have before said^ in this case the 
 attacks should have been simultaneous ', we find^ on 
 the contrary^ that as the depressing* effects of the 
 melancholy condition of the crew was almost hourly 
 undermining" the health of the stoutest of them they 
 as surely became the victims. The Kroomen^ or 
 natives on board the ship had not suffered^ shewing* 
 that they were inured to the miasm^ or were destitute 
 of that condition of blood which would be favourable 
 to a propagation of the materies of the disease. 
 
 The Eclair we learn had left Bona Vista eight 
 days when the first victim breathed his last ; this 
 would give perhaps three or four days for the incu- 
 bation of the disease in the patient^ or supposing he 
 had not contracted the germs of the disease before 
 the crew of the Eclair left the fort^ some local 
 favouring conditions were the means of keeping the 
 germs in a fertilizing state^ for it is clear from this 
 spot the infection spread as from a centre or focus. 
 
105 
 
 Such instances as these mig-ht be multiplied to extend 
 the length of the enquiry, but, I think, to little 
 advantag-e. The chief facts to be g'athered are 
 that an endemic affection became epidemic and pes- 
 tilential, contrary to its usual mode, for the Portu- 
 g'uese oflScial physician, on being* consulted by the 
 Governor of the Island as to the safety of landing- 
 the contaminated crew, said, ^^ No dang-er at all ; I 
 have often brought sick men on shore coming- in 
 vessels from the Afi-ican coast, and I never knew 
 any ill effects to arise." Putting- the most reason- 
 able construction on this emphatic and straig-htfor- 
 ward lang-uag-e, we may presume that ordinary^ 
 remittent, and yellow fever had been commonly 
 imported into the island, for it is not to be supposed 
 but that both forms of disease must have existed 
 among- those sick men who had ^^ often been landed j^ 
 under the sanction of the Portug-uese physician. 
 
 To take another instance 5 intermittent fever or 
 agne, is a disease known among- almost all nations 
 of the world, but it usually occurs in the endemic 
 form onty. It is universally supposed to depend 
 entirely upon marsh effluvia, and we are accustomed 
 to consider it as attaching- only to low lying- coun- 
 tries ;* but this is not always the case, for disease in 
 
 * In 1539, the thirty-first year of Henry the Eighth, 
 was great death of burning agues and flixes ; and such a 
 drouglit that wclles and small rivers were dryed up, and 
 many cattle dyed for lacke of water ; the salt water flowed 
 above London Bridge. — Slowe. 
 
 In 1556, the fourth of Mary, and the third of Philip, 
 
this respect^ like veg-etation^ may be found in various 
 latitudes^ to accommodate itself at varying* altitudes^ 
 to the temperature and climatic relations^ so as to 
 appear indigenous. But thoug-h our prejudices are 
 in favour of a simple miasmatic source of ag-ue^ as 
 its sole cause^ there are some who believe in its 
 infectious nature. M. Sig-aud^ in his work on the 
 Climate and Diseases of Brazil^ speaks of Epidemics 
 oi grave intermittent Fever ^ and Dr. Copland says^ 
 that the epidemic prevalence of ag-ue is a better 
 established fact than its infection^ and has been 
 admitted by most writers.* We have^ therefore^ but 
 to g-o one step further to arrive at infection^ after 
 having found that an endemic disease under pecu- 
 liar circumstances^ though but rarely^ becomes 
 
 about this time began the burning fevers, quarteme agues, 
 and other strange diseases, whereof died many. — Stowe, 
 
 The next winter, 1557, the quarteme agues continued 
 in hke manner, or more vehemently than they had done 
 the last yere. — Stowe. 
 
 * Every writer on the chmate of Egypt has remarked, that 
 the Endemic Fever which is so frequent, originating on 
 the coast, particularly about Alexandria, becomes occasion- 
 ally so virulent, that it cannot be distinguished from the 
 true Plague. — Robertson on the Atmosphere, vol. 2, p. 384. 
 
 " Endemial Fevers of every situation become occasion- 
 ally so aggravated, that they cannot be distinguished from 
 such as originate from contagion ; and in every unusual 
 virulence of this Endemic Fever, it is probable that it may 
 be propagated afterwards by contagion as every epidemic." 
 
 Ibid, p. 388, 
 
107 
 
 epidemic. The number of persons attacked by 
 agne in a malarious district^ in proportion to the 
 population^ is not so g'reat as mig-ht be expected^ con- 
 sidering- that they are always subject by night and 
 day^ more or less^ to respire the air containing* the 
 germs of intermittent fever 3 we mighty therefore^ 
 deny the paludal source of the affection^ as reason- 
 ably as deny infection^ if we found that occasionally^ 
 persons^ though subject to all the usual influences^ 
 yet escaped all injurious consequences. 
 
 There are g-rades and varieties of infectious dis- 
 eases^ from the most inveterate to the most mild and 
 doubtful y but that all^ without exception^ which can 
 in any way be traced to a specific generating and 
 organic cause^ may assume an exalted infectious 
 character^ and that the most inveterate^ on the 
 contrary^ may more resemble the mild and doubt- 
 fully infectious forms^ is a conviction that must 
 be forced on all who pursue this enquiry with 
 unbiassed interest. 
 
 L^ 
 
CHAPTEK III. 
 
 THE EEASONABLENESS OF THE APPLICATION 
 OF THE FACTS TO THE INFERENCE. 
 
 SECTION I. 
 
 THE CHEMICAL THEORY OF EPIDEMICS UNTENABLE. 
 
 It has been inferred that the g-erms of disease 
 possess the property of vitahty^ and a number of 
 facts have been adduced to support the proposition 
 that vitahty is the indwelUng- force by which the 
 matter g-enerating- epidemic and endemic disease 
 exercises its influence over man and animals. The 
 reasonableness of the application of these facts to 
 the end in view has now to be considered. Chemistry 
 cannot account for epidemics. 
 
 Our first subject of reflection points to the che- 
 mical discoveries of the last few years^ and parti- 
 cularly to those of the great German chemist Liebig*. 
 We find in the first parag-raph of his Org-anic 
 Chemistry applied to Physiology and Patholog'y^ 
 the following" words : '^ In the animal ovum^ as well 
 as in the seed of the plant^ we recog-nize a certain 
 remarkable force^ the source of growth or increase in 
 the mass^ and of reproduction or of supply of the 
 matter consumed ] a force in a state of rest. By 
 the action of external influences^ by impreg-nation^ 
 by the presence of air and moisture^ the condition 
 
109 
 
 of static equilibrium is disturbed. This force is 
 called the vital force j vis vitce^ or vitality." 
 
 The doctrine of Liebig*^ that the vital force 
 manifests itself in two conditions^ or rather^ that it 
 is known to be in two diiferent states^ that of static 
 equilibrium as in the seed^ and in a dynamic state^ 
 as in that of g'rowth and reproduction^ is perfectly 
 applicable to the germs of disease ; the static equi- 
 librium is referrible to the matter of vaccine lymph 
 when dried and preserved for use, and the dynamic 
 forces of the matter are known to be in operation 
 during* its reproduction and g'rowth in the system of 
 the vaccinated child. 
 
 Then as to reproduction of matter by any chemical 
 process, our author can furnish us with no examples, 
 for even in his explanation of the causes of disease 
 he is quite silent on this point, merely acknowledging- 
 that diseased products must be either rendered 
 '' harmless, destroyed, or expelled from the body.'' 
 He further says, that " in all diseases where the 
 formation of contagious matter and of exanthemata 
 is accompanied by fever, two diseased conditions 
 simultaneously exist, and two processes are simul- 
 taneously completed," and that it is by means of 
 the blood as a carrier of oxygen that neutralization 
 or equilibrium is established. Liebig thus admits 
 that an agent exists in the blood, capable of dete- 
 riorating it at the expense of the oxygen, which he 
 maintains is contained in the red globules; he 
 further acknowledges that two processes of diseased 
 
110 
 
 action are going" on at the same time^ and though he 
 does not explain them^ I imagine him to mean that 
 new contagious matter is generated and eliminated 
 from the bloody and that at the same time^ there is 
 that condition of body which he would call simply 
 a diseased state^ and characterizes it thus : ^^ Disease 
 occurs when the sum of vital force which tends to 
 neutralize all causes of disturbance^ (in other words^ 
 when the resistance offered by the vital force) is 
 weaker than the acting cause of the disturbance." 
 
 If I rightly apprehend his notions^ they perfectly 
 harmonize with my ideas^ to a certain extent^ on 
 the subject. They accord^ at any rate^ most com- 
 pletely with the theory attempted to be established^ 
 and fully confirm the reasonableness of the ap- 
 plication of the facts recorded to the inference drawn 
 from other sources. The difference only rests on 
 the question whether vitalized or non-vitalized 
 matter is thefons et origo mail. 
 
 How is the production of new matter^ resembling 
 that originally causing the disease^ to be explained 
 by any known hypothesis^ except on the assumption 
 of hving organized matter 1 Though Liebig and 
 Mulder both deny the fact^ that the Torula cerevisiae 
 is the sole agent in the process of fermentation : 
 they both equally fail in shewing upon what it does 
 depend^ and their difficulty rests entirely on their 
 incapacity to explain the uniform reproductive pro- 
 perties of the matter engaged in this^ as well as in 
 all other allied operations. Liebig's statement 
 
Ill 
 
 however on this matter requires notice— he says^ 
 ^* that 27utrifyi?ig bloody white of egg, flesh and 
 cheese^ produce the same effects in a solution of 
 sug-ar^ as yeast or ferment. The explanation is 
 simply this ; that ferment or yeast is nothing* but 
 veg-etable fibrine^ albumen or caseine^ in a state of 
 decomposition/' 
 
 This state of decomposition^ however^ involves a 
 much more complex proceeding*^ than simply a 
 reduction of matter into its elementary forms of 
 g-ases, earths^ and minerals ; for we nowhere find 
 decomposition of this kind g'oing* on without the 
 development of some org-anized bodies^ either animal 
 or veofetable : and since we have seen that the 
 spores of the cryptogami are always in existence in 
 the atmosphere^ and making their appearance under 
 favouring" conditions^ and especially when we find 
 that fermentation is invariably accompanied^ and I 
 may safely say^ preceded by the deposition in the 
 fluid of the sporules of the Torula^ we can hardly 
 believe that they are an}^ other than the sole ag-ents 
 of the process. I have now a considerable quantity 
 of the Torula obtained from the urine of a diabetic 
 patient^ in which they appeared^ as it were^ spontane- 
 ously. After the urine had been allowed access to 
 the air for a certain time, and the whole of the 
 saccharine matter was converted into new com- 
 pounds, reproduction of the Torula ceased ; — and 
 those which remained when the process was 
 completed, still continue as organic cells, deposited 
 
112 
 
 in the bottle in an inert state^ but ready^ on the 
 addition of fresh sug'ar^ as has been proved^ to 
 resume an active existence. These g-erms^ it is now 
 well known, may be dried into powder^ so as to be 
 blown away like dust without any^ or but little, 
 detriment to their vital energies 3 and there is now 
 no doubt that they exist in this condition in the air, 
 as do the spores of mucor, aspergillus, oidium, 
 agaricus, and all other fang-i. . 
 
 Mulder, however, does allow some properties to 
 the yeast vesicle ; he says, '^ a variety of strange 
 ideas have been entertained respecting the nature of 
 yeast \ recent experiments have convinced me that 
 it undoubtedly is a cellular plant consisting of 
 isolated cells. They resemble the composition of 
 cellulose in some respects, but differ from it in many.'' 
 ^^ These vesicles, consisting of a substance re- 
 sembling that of cells, do not contribute in the 
 least to the fermentation, but are exosmotically 
 penetrated during fermentation by the protein 
 compound." These chemists seem to have an 
 instinctive horror of allowing any active properties 
 to the yeast vesicle, that is as far as the conversion 
 of sugar into carbonic acid and alcohol is concerned 
 in the act of fermentation. Dr. Carpenter, as if 
 desiring to conciliate the chemical and physiological 
 disputants, considers that the truth is to be found in 
 the mean of the two extremes,— that is, that the 
 process of fermentation is neither entirely dependent 
 on chemical laws, nor on those laws which preside 
 
113 
 
 over the growth of reproductive matter^ but is a 
 process in which both perform certain offices^ each 
 depending" on the other to produce the combined 
 result^ he thus approaches more nearly to the theory 
 of Mulder^ than that of Liebig". 
 
 But to revert, to Mulder, he speaks of theTorula cells 
 being* " exosmotically penetrated during- the process 
 of fermentation by the protein compound." Now 
 the Torula is acknowledg-ed to be one of the Fung-als, 
 and the chemical constituents of the Fung"i approach 
 very nearly that of animal tissues. They contain a 
 peculiar principle, residing- in and obtainable from 
 them, termed Fung-in, which is as hig-hly azotised as 
 animal fibre. The protein compound alluded to, 
 Mulder says, is not g'luten, because insoluble in 
 boiling- alcohol, and not albumen, because it is very 
 readily dissolved in acetic acid, and he reg-ards it as 
 a superoxide of protein. This superoxide of protein 
 can onl}^ have been produced by a vital action in 
 the cells of the Torula, and as the fung-i consume 
 oxyg-en, and g*ive out carbonic acid, we clearly have 
 all the elementary conditions for their growth in 
 almost all decomposing- animal and veg-etable 
 matters. It is the nature of the fiing^i to live on 
 org-anized matter, but always when it has a tendency 
 to decay ; it is for this reason they have been called 
 " Scaveng-ers." Again, we can understand why 
 some animalized or nitrogenous matter should be 
 necessary for fermentation, otherwise fungi could not 
 grow, nitrogen being an essential constituent of 
 
 I 
 
114 
 
 their structure^ and further fermentation does not 
 commence without the presence of oxyg-en^ and 
 like as in animals^ this g-as supports their existence. 
 The conversion of sug'ar into alcohol is represented 
 by the following* formula : — 
 
 
 
 Result. 
 
 
 Sugar. 
 
 Alcohol. Carbonic Acid. 
 
 Hydrogen . . 
 
 . . 3 
 
 3 
 
 Oxygen . . . 
 
 . . 3 
 
 1 . . 2 
 
 Carbon . . . 
 
 . . 3 
 
 2 . . 1 
 
 If therefore the process were merely of a chemical 
 nature^ where is the necessity for atmospheric 
 oxyg-en to accomplish the end ? it is quite certain 
 that fermentation cannot g'o on without its presence. 
 Let us compare the action of ferment or yeast in a 
 dried state to the action of albumen^ which Liebig* 
 says is sufficient when decomposing* to set up fer- 
 mentation. ^^The white of eg-g-s when added to 
 saccharine liquors requires a period of three weeks^ 
 with a temperature of 96° F. before it will excite 
 fermentation."* But any saccharine liquor on 
 exposure to the air^ thoug-h entirely destitute of 
 albumen or g-luten^ will ferment^ and the Torula may 
 be found in it. I have found the Torula in a gTeat 
 variety of syrups which have spontaneously under- 
 g-one fermentation. I have also discovered that 
 the development of the cells is delayed or accelerated 
 by the nature of the ing-redient used in flavouring 
 
 * Dr. Ure. 
 
115 
 
 the syrups^ with other peculiarities which need not 
 here be mentioned. 
 
 But the conversion of starch into su^ar by means 
 of g'luten requires some notice^ as by some persons it 
 is associated in their minds with the org-anic process 
 of fermentation.* Mulder ascribes the latter in the 
 first instance to the action of heat; e\ddently believ- 
 ing- that the pseudo-catalytic operation of gluten 
 upon starch is the type of all such actions^ and 
 reg-arding- them all as simply chemical^ but we here 
 disting-uish a wide difference ; in the latter instance 
 the g'luten is decomposed^ and rendered unfit for a 
 repetition of the chemical phenomenon^ and if it is 
 desired to renew the action fresh g'luten must be 
 obtained; and a certain temperature kept up^ other- 
 wise the experiment fails. How different is fer- 
 mentation : in the ordinary temperature of the 
 atmosphere the yeast vesicle will multiply^ no incre- 
 mental or unnatural addition of heat is requisite^ 
 and it is one of the commonest and most natural 
 instances of veg-eto-chemistry : the g-rape cannot 
 shed its juice^ nor the sug-ar cane its sap without 
 admitting" these g-erms^ which; under certain condi- 
 
 * "The metamorpliosis of starch into sugar depends 
 simply, as is proved by analysis, on the addition of the 
 elements of water. All the carbon of the starch is found 
 in the sugar ; none of its elements have been separated, 
 and except the elements of water, no foreign element has 
 been added to it in this transformation." 
 
 Liebig, Organic Chemistry, p. 7l« 
 I 2 
 
IIG 
 
 tions multiply themselves and convert the saccharine 
 elements into new compounds. The method by which 
 the conversion of starch into sug-ar is accomplished is 
 thus described by Dr. Ure. He sa3^s that if starch 
 one part be boiled with twelve parts of water and left 
 to itself^ water merely being- stirred in it as it evapo- 
 rates^ at the end of a month or two in summer 
 w eather it is chang-ed into sug-ar and g-um^ bearing- 
 certain proportions to the amount of starch used. 
 But " if we boil two parts of potato starch into a 
 paste^ with twenty parts of water^ mix this paste 
 with one part of the g-luten of wheat flour^ and set 
 the mixture for eig-ht hours in a temperature of 
 from 122'' to 167° F. the mixture soon loses its pasty 
 character^ and becomes by deg-rees limpid^ transpa- 
 rent^ and sweety passing- at the same time first into 
 g-um and then into sug-ar.'^ — '^ The residue has lost 
 the faculty of acting- upon fresh portions of starch." 
 Four points of contrast present themselves for 
 notice as elements of comparison with true fermen- 
 tation. 1st. The starch solution has to be boiled^ so 
 that heat^ by which it is to be supposed that the 
 starch g-lobule is ruptured^ seems to be an essential 
 portion of the chemical chang-e^ and even this may 
 in fact alone be sufficient in such a case to produce 
 some elementary chang-e in the starchy and may 
 prepare it for the subsequent catal3^tic action of 
 some related org-anic^ thoug-h not vital material.* 
 
 * As regards starch there appears to be some pecuUar 
 faculty regarding it. It is converted into sugar during 
 
117 
 
 2nd. Not only a summer heat is necessary^ but a 
 period of one or two months time must elapse before 
 the starch with the water simply becomes converted 
 into sug-ar^ and if artificial heat is to be used to 
 hasten the operation^ a temperature from 122° to 
 167° F. must be resorted to in order to obtain the 
 desired result. 8rd. When e^en this is accom- 
 plished there is no reproduction of the fermenting 
 matter^ and artificial and chemical means must again 
 be applied to repeat the experiment. 4th. The 
 conversion of starch into sugar can be accomplished 
 without the presence of gluten at all^ by the aid 
 only of temperature and time. It seems to me^ 
 therefore^ to be entirely unnecessary to occupy more 
 space in the elaboration of a proof of the doctrine 
 that the germs of the Torula are the sole agents in 
 the conversion of saccharine fluids into alcohol and 
 carbonic acid. By another chemical process starch 
 can be converted into sugar^ but I am not aware 
 that hitherto any method has been discovered by 
 which sugar can be converted into alcohol except by 
 the process of fermentation proper. 
 
 I have been thus particular in commenting* on 
 this subject^ as it bears, in an especial manner^ on 
 the question under consideration. 
 
 the ripening of fruit, and it is just possible that being as 
 it is of a cellular natiu-e, the property of vitality may 
 attach to it until it has, by being converted into sugar, 
 fulfilled its destination. 
 
118 
 
 The physiolog-ist cannot afford to lose this pro- 
 cess from the category of chemico-vital^ or bio- 
 chemical manifestations.* The philosophy of the 
 ag'e has a tendency to make every thing- chemical ; 
 it is true that the Divinity is as much seen in the 
 laws which govern the elementary particles of mat- 
 ter^ as in those laws which preside over the trans- 
 mutation and sustentation of those elementary and 
 inorganic particles_, when compounded in the tissues 
 which are engaged in the formation of living beings. 
 The laws by which acids and alkalies neutralize each 
 other^ and the affinities single^ double and elective^ 
 which the particles of matter exhibit^ together with 
 the influences of light^ heat^ and electricity upon 
 almost every condition of matter^ are as truly won- 
 derful as the creative power. Man may^ in many 
 instances^ imitate the processes of nature^ he can 
 render iron magnetic^ and form alkaloids^ but the 
 
 * Though I do not consider that the fermentation pro- 
 cess is a fac-simile of diseased action,, yet I think its 
 phenomena generally afford an apt illustration of the 
 changes which may be effected by living germs. Many 
 able chemists still maintain the (entire dependence of fer- 
 mentation upon the Torula ; " M. Blondeau propounds 
 the view that every hind of fermentation is caused by the 
 development of fungi." 
 
 The varieties of opinions found in the literature of this 
 subject^ forms a curious specimen of scientific enquiry, and 
 is suflBcient alone to convince us of its vast importance and 
 extensive relations. 
 
119 
 
 laws which g*overn the particles of matter are still 
 the secret of the whole proceeding's. We do but in- 
 terpret the language of nature in discovery^ the book 
 is ever open before us^ and every atom of the world 
 is a word and a theme^ capable of occupying the short 
 span of sublunary existence allotted to man. We 
 have read of ^^ sermons in stones/' but a book has 
 been w ritten on a " pebble.^'* 
 
 To return^ as we every where in nature find a 
 gradual transition in the forms^ arrangements and 
 properties of matter^ so we may expect to find a 
 link between the inorganic and vital chemistry of 
 nature. The fungi^ by which we contend this 
 transition appears to be accomplished^ are also a 
 link in chemical composition^ between the animal 
 and vegetable kingdom^ and not only in that^ but 
 in their subsisting upon matter which has been or- 
 ganized^ they are deoxidizers and reducers^ as the 
 vegetable kingdom in its highest function is a com- 
 pounder. To their functions and ofiices in the 
 great scheme of creation^ we may fairly apply our- 
 selves with a sure and certain result of the most 
 interesting discovery. Is it no hint that wherever 
 decaying organic matter is found, there do we find 
 fungi ? is it no hint that they are found in all parts 
 of the world ? that even in snow the germs of fungi 
 will grow and multiply to such an extent, accord- 
 ing to Capt. Ross, that the protococcus was seen 
 
 * By Dr. Mantell. 
 
1^6 
 
 by him^ clothing" the sides of the mountains at 
 BafBn^s Bay^ rising-^ according- to his report^ to the 
 height of several hundred feet ^ and extending- to the 
 distance of eight miles ? 
 
 Even stones contain in their interior^ or interspaces 
 of their structure^ the germs of fungi. A species 
 of Tufa is found in the vicinity of Naples of a porous 
 texture^ which^ when moistened and shaded^ pro- 
 duces vast mushrooms^ four or five inches high^ and 
 eight or ten inches broad.* This author further 
 says : ^^ In the Maremma^ where the volcanic tufa 
 is the basis of the soil the surface is intermixed with 
 the animal remains of departed empires^ and the 
 ordure of cattle^ is covered with grasses of old 
 pasturages^ and is wet with heavy dews. Every- 
 thing^ therefore^ conspires there to a fungiferous 
 end.'^ 
 
 They are found growing in and upon both vege- 
 tables and animals. Nees von Esenbeck imagined, 
 that minute forms multiplied themselves in the 
 atmosphere; and really, when we consider the 
 amount of effluvia composed of the atoms cast off 
 from the bodies of living or decaying organic 
 matters, which are incessantly passing into the 
 atmosphere, the conjecture is not an unreasonable 
 one. The minuteness of those, which we know are 
 always found growing on decomposing bodies, does 
 not preclude the possibility, nay, further favours 
 
 * Mitchell on Fevers. 
 
121 
 
 the probability^ that others infinitely more minute^* 
 may be destined to remove the more subtle and 
 vaporous particles which escape into the air. 
 
 We can^ therefore^ I think^ conclude^ that the 
 lower tribes of veg-etation^ may consistently be re- 
 garded as capable of existing* in almost any con- 
 dition^ and almost under any circumstances^ they 
 may be made to g-row in plants by inoculation^ as 
 shewn by De CandoUe, and Dr. Hassall. If the 
 stem of wheat also is inoculated with vibriones, they 
 will make their appearance in the gTain.t If the 
 seed contain them and have not lost its g-erminating* 
 properties^ these worms will be found ag^ain in the 
 g-rain. If the g'rain containing* them be dried for 
 years^ and moistened ag*ain with water^ these ani- 
 malcules^ according- to Bauer and Steinbach^ will 
 present all the phenomena of life. This experiment 
 I have witnessed^ and can confirm the statement. 
 These animalcules in the diseased ^ain^ have under 
 the microscope the appearance of an immense num- 
 
 * We wonder, and ask ourselves : " What does small 
 mean in Nature?" — Scldeiden's Lectures on Botany. 
 
 t Speaking of the bunt in wheat : " It appears certainly 
 to be contagious, fro ii numerous experiments, which shew 
 that the contagious principle lasts a long time. I have 
 tried it myself; some, however, doubt it, but it cannot 
 be denied, that seed sown, infected with bunt, produces 
 plants similarly aifected; every one who has had the 
 slightest experience must be convinced of it." — Essay on 
 the Diseases of Plants. Count lie. 
 
122 
 
 ber of eels crowded together in a small space^ and 
 presenting" a movement more^ perhaps^ vermicular 
 than any other^ and it is continued for a consider- 
 able time. Now if these animalcules^ or their ova^ 
 can be proved to pass with the sap to the seed^ there 
 can be no difficulty in comprehending* how g"erms^ 
 considerably more minute and of a veg^etable nature^ 
 should be found subject to the same peculiar mode 
 of obtaining" an entrance into animals and vege- 
 tables for sustenance. '^ It is usually imag"ined/' 
 says Dr. Carpenter^ ^^that the g-erms liberated by 
 one plant are taken up by the roots of others^ and 
 being" carried along- the current of the sap^ are de- 
 posited and developed^ where vegetation is most 
 active." 
 
 The chemical theory of disease would be better 
 sustained by a comparison of '^ the artificial forma- 
 tion of alkaloids/' and the phenomena of trans- 
 formation of blood into the tissues of animals^ 
 and their degeneration into effete matters^ and of 
 sap into the tissues of plants and their degenera- 
 tions. 
 
 Professor Kopp of Strasburg^ s^yS; ^^In a che- 
 mical point of view^ the alkaloids are remarkable 
 for their composition^ for their special properties, 
 both physical and chemical, and for the interesting 
 reactions to which many of them give rise, when 
 exposed to the influence of different reagents. 
 Considered medically, the organic bases are dis- 
 tinguished by their energetic properties. They 
 
123 
 
 constitute at the same time^ the most violent and 
 sudden poisons, and the most valuable and heroic 
 remedies." 
 
 Upon this very intricate and interesting part of 
 chemical philosophy, it is rather dang'erous to enter 
 without a thoroug'h and practical knowledg^e of the 
 subject. This, however, falls to the lot of few men. 
 We, who are engaged in the study of disease, and 
 of the best methods of cure, are obliged to take the 
 investigations of the analytical chemist, and examine 
 them for ourselves in the intervals of leisure allowed 
 us during the active exercise of our calling. 
 Though with less advantages for the study of these 
 transcendental relations of organic and inorganic 
 matter, we are not, nevertheless, precluded from 
 forming* our opinions on their practical bearings to 
 the phenomena and treatment of disease. 
 
 That there is a matter of a poisonous nature con- 
 cerned in the production of endemic and epidemic 
 aifections, cannot be doubted by any one ; I believe 
 indeed, that the chemical theorists admit this, at 
 all events Liebig does, for he says, ^^The morbid 
 poison changes in the blood are fermentative, just 
 such as occur in beer making." If we start, then, 
 with the consideration that poisons, in a chemical 
 point of view, are the objects of our research ; the 
 obvious course to take is to enquire what is the 
 source of poisons generally, and what their effects 
 on the animal economy ? The mineral poisons are 
 entirely excluded from the enquiry by their inapti- 
 
124 
 
 tude for diffusion^ and their uniform effects upon 
 all persons^ differing* only in degree in their opera- 
 tion. The same objections apply to g-aseous poisons^ 
 except that to them the property of diffusion would 
 be admitted.* We come then to the alkaloids^ 
 which constitute^ as Kopp says^ the most violent 
 and sudden poisons. For the production of alkaloids 
 by artificial means^ org-anic products of some kind 
 are required. Artificial heat^ powerful chemical 
 ag-ents or leng-th of time^ are^ as far as information 
 at present extends^ the indispensable requirements 
 to induce these peculiar chang^es in matter. The 
 only instance I can find, in which elementary mat- 
 ters can by artificial means be combined, so as to 
 resemble the products of nature, is that of the con- 
 version of carbon and nitrog-en into cyanog"en. But 
 the process by which this is accomplished, leads 
 rather to doubt whether it be really and simply by 
 a combination of elementary carbon and nitrogen. 
 I extract the following* from the Annual Eeport 
 of the Prog-ress of Chemistry, for 1848. '^ H. Del- 
 bruck has performed some experiments on the 
 important subject of the formation of cyanog*en. 
 He confirms the statements of Desfosses and 
 Fownes, inasmuch as a weak hut distinct formation 
 of cyanog-en was observed on ig-niting* sugar- 
 
 * We have already spoken of the effects of these poisons, 
 and have stated that the amount of each poison capable of 
 destroying the body is pretty accurately known. 
 
125 
 
 eharcoal* with carbonate of potassa in an atmos- 
 phere of nitrog'en." The use of sugar-charcoal^ 
 may be perhaps an explanation of the weak forma- 
 tion of cyanogen^ for in these numerous and 
 successive chemical changes of matter^ it is 
 impossible to say how many sources of error may 
 arise. The constant contradictions of each other^ 
 and the opposite statements made by chemists^ of 
 equal eminence^ leave us in a wilderness of doubt^ 
 from which we are not likely to be freed^ until 
 definite laws shall be discovered to act as a guide 
 in the comprehension of the higher branches of 
 Chemical Philosophy. 
 
 But supposing that the generation of alkaloids 
 could take place in the body^ or some analogous poi- 
 sonous matter^ we have yet to imagine a whole host of 
 peculiar and essential conditions to effect this change, 
 besides an atmospheric agent or agents to set in mo- 
 tion those compositions and decompositions, capable 
 of bringing out these new products from the elements 
 of blood. We are aware that in the blood, carbon 
 and nitrog*en are sufficiently abundant as well as 
 saline compounds, to generate c^^anides, and, with 
 hydrogen also there in plenty, hydrocyanates, and 
 thus from them many other poisonous products, but 
 how is all this to be effected ? And even if effected, 
 it is yet a question if such compounds can in any way 
 simulate the attacks of epidemic disease. We have 
 
 * The italics are my own. 
 
126 
 
 already shewn that the amount of most poisons 
 necessary to destroy an individual^ can be pretty 
 clearly estimated^ and their modus operandi is 
 tolerably well understood. Again^ the most essen- 
 tial part^ in which all chemical theory fails^ is an 
 explanation of the reproduction of contagious matter. 
 The catalytic process^ by which decompositions 
 are said to be effected^ and in which Liebig* includes 
 the various fermentations^ is one of those chemical 
 relations of matter to matter^ considered by some 
 as the probable cause of infection. Mr. Simon^ in 
 a late lecture^ has said^ '^ I consider the phenomena 
 of infective diseases^ to be essentially chemical^ and 
 I look to chemistry to enlighten the darkness of 
 their pathology. Qualitative modifications^ affect- 
 ing the molecules of matter as to their modes of 
 action and reaction^ are such as form the subject of 
 chemical science 5 and those humoral changes which 
 arise as the result of infection clearly fall within the 
 terms of its definitions.'^ Further on he adds : " The 
 phenomena of infected diseases appears then^ in 
 many respects^ to be sui generis. Certainly they 
 are chemical. Prohahly they belong to that class 
 of chemical actions called catalyticr^ 
 
 * Gmehn says : " But the mode of action in these trans- 
 formations, sometimes admits of other explanations; and 
 when this is not the case, our conception of it is by no 
 means sufficiently clear to justify the positive assumption 
 of this, so called contact-action or catalytic force, which, 
 after all, merely states the fact without explaining it." — 
 GmelirCs Hand-hook of Chemistry, vol. i. p. 115. 
 
127 
 
 It is not improbable that something- resembling a 
 catalytic action may take place in the blood in those 
 diseases of endemic and epidemic origin^ but that it 
 can be by a chemical process alone is contrary to 
 all experience of catalytic operations^ for except in 
 the instance of fermentation proper^ there is no 
 multiphcation of the fermentative matter. The 
 action of the matter of contagion seems to stand on 
 the confines between electro-chemical and bio-chemi- 
 cal manifestations^ and so long* as no chemical 
 explanation can be given for the multiplication of 
 the matter of infection^ the most rational course to 
 adopt is to assume that life under some unknown 
 form is^ as we every where find it, the sole reproduc- 
 tive ag-ent. 
 
128 
 
 SECTION II. 
 
 THE ANIMALCULAR THEORY OF EPIDEMICS UNTENABLE. 
 
 The animalcular theory of disease^ after remain- 
 ing- almost unnoticed for nearly two centuries^ has 
 been again revived under the auspices of Dr. 
 Holland in this country^ and Henle of Berlin. And 
 thoug*h not entirely buried in obscurity^ this theory 
 had completely failed to modify the practice of 
 physicians in the treatment of those diseases which 
 were supposed to owe their existence to these invi- 
 sible atoms of created being*. The resuscitated 
 notions and all their amplifications^ to which the 
 advance of science has contributed so much^ are 
 threatened with a like fate^ an absence of all practi- 
 cal results. 
 
 Thoug-h I would not attempt to deny the possi- 
 bility^ nay^ even the probability^ that insect life may 
 yet be discovered as the cause of some diseases^"^ still 
 
 * The history and symptoms of some epidemic diseases, 
 such as cholera and influenza^ are not inconsistent with the 
 hypothesis that they are caused by the sudden develop- 
 ment of animalcules from ova in the blood. But there is 
 a total want of direct observation in support of this hypo^ 
 thesis. — Dr. Williams* Principles of Medicine. 
 
129 
 
 there are many and cog-ent reasons ag'ainst both^ 
 and which are at variance with facts and observa- 
 tions. Where insect Hfe has been found associated 
 with disease, it more especially appears as a conse^ 
 quence than as a cause. 
 
 Disease^ in its most enlarged sense, is a conversion 
 of one form of matter into another y it is a transfor- 
 mation of healthy blood and tissue into new and 
 abnormal products. AVhere insects in all their 
 variety of forms are discovered, their voracious 
 propensities are their chief characteristics, they are 
 the consumers of matter after its partial disinteg-ra- 
 tion, if animal matter be their food, unless they be 
 carnivorous and predacious, or if herbivorous they 
 usually feed upon the tender shoots of plants. Thus 
 far we are certain of the manner in which insects 
 destroy living- matter ; it is a process the unassisted 
 eye may every where witness, and which experience 
 has amply attested. To take, however, the animal- 
 cular world as it presents itself to us under the 
 microscope, and as the intermediate step between 
 the manifest and the hidden for a fairer and more 
 direct method of reaching* the truth, what do we 
 observe to be the ruling* law of infusory instinct ? 
 They live to feed ; the term polyg*astrica sufficiently 
 implies their natural tendency to consume. The 
 simplest form of animalcular life, seen in the g*enera 
 of monads, still preserves the animal character by 
 possessing" a stomach or stomachs in which the food 
 is received, to be digested for the nourishment of the 
 
 K 
 
130 
 
 system ; and even some of these minute objects 
 which vary in size from one two-thousandth^ to one 
 three-thousandth of a line in diameter^ are said to 
 be carnivorous and predacious. Upon this fact 
 alone^ I would place the improbability of insects 
 being" the cause of epidemic disease. Each insect 
 doubtless has its own peculiar food^ and whether it 
 be a veg-etable or animal feeder^ it consumes the 
 matter already organized for conversion into its own 
 tissue^ and the only change which could be affected 
 by them in the blood, would necessarily be that of 
 appropriation of some one of the constituents as 
 an element of food; when that food is digested^ 
 (taking- dig-estion generally as an identical process^) 
 the excrementitious matter is composed of secretions 
 and disorganized matter^ mixed together as an effete 
 product; and destined then for reorganization by the 
 vegetable kingdom. Now all animals^ whether 
 they be large or small^ live on organized matter^ — 
 they convert that matter into an inorganic form, 
 and I cannot help imagining that if epidemic 
 diseases and fevers depended upon animalcular 
 growth and development in the blood or tissues of 
 the body, the excretions or secretions from them 
 would have yielded some information to the search- 
 ing enquiries of the chemist, supposing that these 
 excretions and secretions were capable of reaching 
 to a suflScient amount in quantity, to bring about 
 those fatal effects of poisoning, we witness in 
 Cholera and other epidemic affections. Insects, I 
 
131 
 
 believe are poisonous only by their secretions^ and 
 thoug-h they are known to multiply with exceeding 
 rapidity^ I can hardly imagine that by their deve- 
 lopment^ however rapid^ they could produce such 
 a change in the human body^ as to bring about 
 the speedy dissolution^ and generally gangrenous 
 appearance^ that has invariably been observed in 
 those suddenly dying under the influence of epidemic 
 poisons. The vibriones^ whose destructive effects on 
 wheat are so well known^ are a genus of animalcules^ 
 which at first would seem to favour the animalcular 
 theory in a remarkable manner ; for on examining 
 them^ they do not appear to possess any other 
 structure than a gelatinous absorbing mass, in this 
 respect resembling a vegetable. 
 
 But Ehrenberg'^s scrutiny corrected the error of 
 De Blanville, and shewed, that they were far from 
 being agastria, or stomachless animals. The Rev. 
 William Kirby says, " Ehrenberg has studied the 
 vibriones in almost every climate, and has discovered, 
 by keeping them in coloured waters, that they are 
 not the simple animals that Lamarck and others 
 supposed, and that almost all have a mouth and 
 digestive organs, and that numbers of them have 
 many stomachs." All the discoveries indeed which 
 have been made on the minuter forms of animal 
 life, have tended to confirm the doctrine that the 
 stomach is the exponent organ of an animal ; that 
 is, in all animals there exists, in a variety of modified 
 conditions, a receptacle for food. Some of the 
 
 K 2 
 
132 
 
 animalcules^ however^ are still supposed to exist by 
 absorption^ as the vinegar eel^ vibrio anguilla* but 
 when we find that the law is^ g-enerally speaking*^ 
 that the receptacles of food become multiplied in 
 number in these minute being-s^ and the vibriones 
 which were supposed to be stomachless^ have been 
 proved to emulate their associates in the number 
 of these organs 5 it would be more reasonable to 
 conclude that our imperfect vision is the barrier to 
 their detection^ rather than to suppose that they do 
 not exist. Besides, when we are told on undoubted 
 authority that some of the animals of this class^ 
 have as many ^^ forty orjifty stomachs ] the least 
 we can do^ is to allow that all of them possess^ at 
 least one digestive organ^ though we may not be 
 able to detect it.f 
 
 So far then for the consideration of animalcular 
 structure : let us now more particularly enquire into 
 their destructive habits^ and their functions^ inasmuch 
 
 * Since writing the above, I have referred for informa- 
 tion on this subject, and find, that the Anguillula aceti 
 exhibits sexual distinctions ; and that the ovaries of the 
 females are situated on each side of the alimentary canal. 
 — Cyclo. Anat, and Phys. Art. Entozoa. 
 
 t Speaking of the examination of the infusory animal- 
 cules — Mr. Kirby says : " But to us the wondrous 
 spectacle is seen, and knoT\Ti only in part ; for those that 
 still escape all our methods of assisting sight, and remain 
 members of the invisible world, may probably /«r exceed 
 those that we know" — Bridgewater Treatise, vol. i. p. 158. 
 
133 
 
 as they may be supposed capable of eng-endering" 
 epidemic diseases and fever. The truly carnivorous 
 animalcules^ or those truly herbivorous in their 
 instincts^ we may presume to be beyond the 
 limits of our enquiry. We have rather to do 
 with those which take an intermediate position, 
 namely, those which feed upon matter underg-oing- 
 decomposition, or upon fluids containing* org-anic 
 matters in solution, or suspension. If w^e take 
 Entozoa g-enerally, they may be considered as most 
 conveniently to be placed in this intermediate class 5 
 and here we find still the dig-estive apparatus, and 
 more than this, — for upon the modifications of the 
 organs appropriated to dig^estion is their classifica- 
 tion founded. '^ Rudolphi divided the Entozoa into 
 Sterelmintha, or those in which the nutrient tubes 
 without anal outlet are simply excavated in the 
 g-eneral parenchyma, and into the Coelelmintha, in 
 which an intestinal canal with proper parietes floats 
 in a distinct abdominal cavity, and has a separate 
 outlet for the excrements."* 
 
 How do these animals obtain their sustenance, 
 and what chang-es can they produce upon the vital 
 fluid of the body ? Analogy is here our only g-uide. 
 If the trichina spiralis is examined, it is found to be 
 enclosed in a cyst containing- fluid 3 and this is, 
 
 * Mr. Owen has added another class, as the first, called 
 Protelmintha, which comprises the cercariadse and vib- 
 rionidse. 
 
134 
 
 doubtless, the source of its nutriment^ and contains 
 in solution the elements for its nutrition; but in 
 this instance there is no selection^ and there can be 
 no locomotion to an extent sufficient to imply 
 searching* for food^ as the animalcule in its natural 
 state^ when taken from the human muscle, is found 
 coiled upon itself^ making' about two and a half 
 turns. The fluid of the cyst is thus in all likelihood 
 prepared by endosmosis^ for the immediate and 
 appropriate nutrition of the parasite. The cyst is 
 thus the part which performs the diseased process^ 
 the containing- animalcule is merely the consumer of 
 what is prepared for it by the cyst. And this would 
 seem to be the rule with all parasites^ of the encysted 
 kind. 
 
 We have alluded to the vibriones which are found 
 in the fluids of living* bodies^ and the trichina which 
 is found in the solid muscle 5 we have now to refer 
 to those which infest the cavities. It was, I believe, 
 Ehrenberg-, who shewed that the tartar which accu- 
 mulates on the teeth is composed of the debris of 
 minute animalcules; in fact^ that it consists of 
 calcareous matter, having- once formed a portion of 
 the structure of their bodies^ the ubiquity of these 
 creatures is therefore as much and clearly established 
 as the lower forms of veg-etation. The intestinal 
 worms, of which perhaps the Taenia is the most 
 curious and important to be noticed, are from the 
 locality in which they are found, chiefly injurious 
 by the irritation they set up, and by appropriating- 
 
135 
 
 to themselves the nutrient juices elaborated in the 
 process of animal dig-estion^ thus depriving- the in- 
 dividuals they infest of that which was destined for 
 their own nourishment. In this^ as in all associated 
 instances^ the character by which these parasitic 
 animals are marked is their consuming* propensity. 
 There is^ however^ one more observation to make 
 upon parasitic g-rowths j but the question is yet 
 unsettled in what king-dom of nature is the acepha- 
 locyst^ or hydatid^ to be placed. Mr. Owen says^ 
 ^^ As the best observers ag-ree in stating*^ that the 
 acephalocyst is impassive under the apphcation of 
 stimuli of any kind^ and manifests no contractile 
 power^ either partial or g-eneral^ save such as results 
 from elasticity^ in shorty neither feels nor moves^ it 
 cannot^ as the animal kingdom is at present charac- 
 terized^ be referred to that division of organic 
 nature.'' 
 
 We thus arrive at the simple cell^ and the multi- 
 plication of living beings by cell buds; it is the 
 point at which the confines of the animal kingdom 
 are reached^ and at which we are driven to specula- 
 tion. The hydatid Uves like a plant^ by imbibition ; 
 and procreates, like a plant, by budding, either en- 
 dogenously or exogenously, as regards the original 
 or parent cell.* 
 
 * " It is probable that in the waters of our globe an 
 infinity of animal and vegetable molecules are suspended, 
 that are too minute to form the food of even the lowest 
 
130 
 
 This condition of being-^ sug*g-ested the notion of 
 Protozoa^ or first animals^ in the same way that the 
 purely cellular plants^ that is^ each individual^ con- 
 sisting- of a sing-le cell^ g-ave the idea of Proloph3^ta^ 
 or first plants. Mr. Kirby thus expresses himself 
 on this subject : ^^ The first plants^ and the first 
 animals^ are scarcely more than animated molecules^ 
 and appear analog-ues of each other; and those 
 above them in each king-dom represent jointed 
 fibrils.^' 
 
 Admitting"^ then^ that animals as well as plants 
 exist in the form of simple cells^ and that their 
 multiplication proceeds apparently upon the same 
 principle in each^ it is nevertheless abundantly 
 manifest; that the cellular form of perfect individuals 
 is infinitely more numerous in the veg^etable than in 
 the animal king-dom. 
 
 and minute animals af the visible creation : and therefore 
 an infinite host of invisibles was necessary to remove them 
 as nuisances." — Bridgewater Treatise, vol. i. p. 159. 
 
 " When Creative Wisdom covered the earth with plants^ 
 and peopled it with animals, He laid the foundations of the 
 vegetable and animal kingdoms with such as were most 
 easily convertible into nutriment for the tribes immediately 
 above them. The first plants, and the first animals, are 
 scarcely more than animated molecules,* and appear analo- 
 gues of each other ; and those above them in each kingdom 
 represent jointed fibrils.^t — Bridgewater Treatise, vol. i. 
 p. 162. 
 
 * Globulina and Monus. t Oscillatoria and Vibrio. 
 
137 
 
 From the mosses downwards to the fungi^ the 
 whole structure of the plants consists of an ag'g're- 
 gation of cells^ more or less in number and com- 
 plicate arrangement^ until^ through a variety of 
 gradations^ we reach the single cell as a perfect 
 individual. 
 
 It is rather remarkable^ that the lower forms of 
 vegetables and animals seem to derive their nutri- 
 ment from matter of a similar kind, and though 
 the office of plants is as a rule^ to convert inorganic 
 into organized matter^ it appears that some of the 
 fiingi may live as animals do on organic matter 
 when in a state of solution. This, however, is un- 
 certain ; for we do not know what are the first signs 
 of decomposition in organized bodies, and for aught 
 we can tell, it may be pei'petually going on ', so far 
 as the disengagement of carbon from the system is 
 concerned, this is certain ; but whether the nitro- 
 genous compounds also are subject to a resolution 
 into their elements in the living body, is another 
 question, and not so eas}^ of solution. The partially 
 decomposed elements of animal structures are, how- 
 ever, particularly adapted for the nutrition of the 
 lower forms of vegetation ; it is, indeed, from the 
 decaying organic matters that the fungi derive, it 
 may be said, their entire food. 
 
138 
 
 SECTION III. 
 
 SKETCH OF THE PHYSIOLOGY AND PATHOLOGY OF PLANTS 
 AND ANIMALS. 
 
 Animals and plants depend for their existence 
 upon a nutritive fluid^ which permeates their 
 structure ; it is the element from which all their 
 secretions are formed^ and their organs are 
 nourished. 
 
 The food of animals is composed of previously 
 org-anized matters^ and is conveyed into a reservoir 
 called a stomachy where it underg*oes a process of 
 solution, previously to entering" the circulation. At 
 this period^ the animal and the plant ag-ain present 
 points of resemblance^ the lymphatics or absorbent 
 vessels take up the products of dig-estion^ and convey 
 them to the blood-vessels^ where ming-ling" with the 
 current of the bloody they are conveyed to the lung's^ 
 there to underg-o a process of oxygenation before 
 they become fitted for the renovation of the tissues of 
 the body. Such is the nature of the food of man^ 
 that it contains all the elements necessary and 
 adapted for transformation into bone^ muscle^ brain^ 
 and parenchyma^ as well as the other tissues of the 
 body; besides other elementary matters^ which, 
 thoug-h they form a very insignificant portion of 
 
139 
 
 animal textures^ from their constant presence in the 
 vital fluid^ evidently perform some important offices 
 in the g-eneral economy of life 5 they are partly^ 
 perhaps^ occupied in forming* constituents of secre- 
 tions. 
 
 Plants do not require a stomachy — the humus or 
 soil to which they are fixed is the laboratory^ Avhere 
 the nutritive matter is prepared in a state fit for 
 absorption by the spong-ioles of their roots^ and 
 these correspond to the lymphatics of animals; 
 after being taken up by the spong-ioles^ this new 
 fluid ming-les with the sap^ and passes to the leaves 
 or breathing* apparatus of plants^ where carbonic acid 
 gas combines with the crude vital liquid^ and converts 
 it into a condition fit for all the offices to be per- 
 formed by the plant : viz. the growth of tissues^ and 
 the elaboration of secretions. 
 
 The tissues^ however^ of plants^ though more 
 simple in their nature^ present a much more varied 
 character than those of animals^ when the different 
 species are compared. 
 
 The bones of animals which give them their form^ 
 are invariably constituted of phosphate and car- 
 bonate of lime^ deposited in a matrix of gluten ; 
 muscle^ nerve^ brain^ tendons^ and ligaments^ have 
 nearly^ if not completely^ an identical composition 
 throughout the w hole range of the animal kingdom : 
 their secretions^ however, vary much more con- 
 siderably, as also do the secretions of vegetables. 
 But vegetable tissue may contain, as in the stems of 
 
140 
 
 grasses^ a considerable amount of silex^ and some 
 notable quantity of sulphur^ and so essential to 
 their existence is the former element^ that they can- 
 not live without its presence in the soil^ and also 
 with it an alkali^ to render it soluble. A large 
 amount of soda^ is an invariable attendant upon the 
 structure of marine plants^ as potash is of those 
 growing- on the land. 
 
 Thus^ whether we reg-ard the health of animals^ 
 or vegetables^ we discover^ that besides the matters 
 which are absolute^ indispensable for the nutriment 
 of the tissues which undergo rapid transforma- 
 tion^ those of a more permanent and durable 
 nature require in an almost insensible degree^ a 
 restitution of elements ; and though not apparently 
 absolutely necessary to preserve vitality in the beings 
 yet have so marked an influence over it^ as to 
 indicate an extensive bearing of each indivdual part^ 
 on the whole associated entity. 
 
 The elementary tissues of both kingdoms have 
 been traced^ in whatever form they may be found^ 
 to a cellular origin. The minutest vegetable germ^ 
 is a cell containing a granular matter within it^ 
 and even man himself, in his embryonic state^ may 
 be represented as an insignificant point in the 
 realms of space j and might be placed side by side 
 with the smallest particle of living matter^ without 
 suffering by the comparison. 
 
 The laws by which the development of these 
 elementary cells is regulated^ so that each e^vances 
 
141 I' 
 
 to its limit^ and fulfils its destination^ is one of 
 those inscrutable and overwhelming" mj^steries of 
 nature^ which leads the admirer of creation on and 
 on into the abyss of the future^ and fills his soul 
 with aspirations for that time^ when the veil of 
 ig-norance shall be withdrawn. But this is not my 
 subject. 
 
 The org*anization of the two animated king*doms, 
 is then reg-ulated by definite laws^ and all matter, 
 whether acting- upon them as agents of nutrition 
 or destruction, are equally under their dominion ; 
 to investigate and to endeavour to fathom some 
 of these laws, is the aim I have in view. 
 
 The sap is to the plant, what the blood is to the 
 animal,— the elements of nutrition and secretion 
 are contained in it, and whatever interferes with its 
 normal constitution by subtracting- from, or adding- 
 to it, deteriorates its qualities, and retards or ac- 
 celerates the functions of the individual. Excess or 
 deficiency of the natural elements may also be 
 a source of disturbance ; if carbonic acid be too 
 abundantly liberated in the soil, as Dr. Lindley 
 expresses it, '' plants become g-org-ed f and if, on 
 the other hand, the elimination be too slow, they 
 become starved. It has been also shewn, that 
 plants though they give out oxygen from their 
 leaves, do not throw it off as animals do carbonic 
 acid from their lungs; but that this arises as a 
 result of digestion, and the fixation of carbon in 
 the system, and that they really respire oxygen as 
 
142 
 
 animals do^ and ^ve off carbonic acid, both by day 
 and nig'ht. 
 
 That lig-ht is the stimulant of the digestive 
 functions, and that, therefore, during- the day, the 
 amount of oxygen thrown off, far exceeds the 
 amount of carbonic acid liberated during- the same 
 period. 
 
 The great and important distinction between 
 animals and plants is, that the former possess a ner- 
 vous system, by which they are subject to a ver}^ 
 extended series of psychological relations; it is 
 in these chiefly, if not entirely, that we are to look 
 for the distinctive and well-marked differences of 
 diseased action. In animals there are special 
 media of communication between the sources of 
 dynamic power, and the parts upon which the force 
 is exercised: and again, a return communication 
 exists, which conveys impressions to the source of 
 power, and to use a simple comparison, a system of 
 telegraphing is in incessant and watchful operation. 
 This force is influenced and modified in its 
 action, when exercised in the regulation of nu- 
 trition, growth, and reproduction of tissues, by the 
 passions and emotions of the mind. All the 
 secretions and functions of the body are more or 
 less susceptible of being accelerated, retarded or 
 modified by the psychical relations of mind and mat- 
 ter. Though we are apt to imagine that in man 
 alone, these phenomena obtain much importance — 
 there can be but little doubt, that wherever a nerv- 
 
143 
 
 ous system exists^ whether in the form of aggreg-ated 
 or diffused g-ang-lia^ the interdependence of force and 
 organization^ each upon the other^ bears a certain 
 and definite physiological comparison , the more 
 aggregated the ganglia^ the more close^ intimate^ 
 and extensive the psychical connexions^ and the 
 gradations pass downwards^ until they appear to be 
 lost on the confines of the vegetable kingdom. 
 
 The diseases of plants and animals deserve a more 
 careful comparison than^ I think^ has hitherto been 
 bestowed upon them.* If the study of physiology^ 
 or an enquiry into the laws which regulate the func- 
 tions of living beings in a state of healthy has been 
 materially aided by the intimate knowledge of 
 vegetable physiology^ which^ from the simple struc- 
 ture of plants, so favours the experiments of the 
 student, there is every reason to suppose that vege- 
 table pathology may also lead us to an equally 
 important and useful result. 
 
 It is quite certain, that if a healthy seed, or leaf- 
 bud, be placed in such a situation, that, according* 
 to the laws known, it will in all likelihood germi- 
 nate, if all the elements for its sustenance exist in 
 the soil, and the temperature and hygrometric 
 
 * "A treatise which should present a systematic ar- 
 rangement of all the diseases of plants, giving in detail the 
 exact history of each, and adding the means of preventing 
 and curing them, would certainly be of the greatest utility 
 to agriculture/^ — Essay on the Diseases of Plants, Count 
 Philippo i?e, translated into Gardener s Chron, 
 
144 
 
 condition of the atmosphere are adapted to it^ a 
 healthy plant will be the result. Lig'ht, heat, 
 moisture^ and soil are therefore to be considered 
 as the ag'ents required to exist in a certain balance, 
 or proportion, in reference to the health or power 
 of vitality of the plant. Within a certain amount 
 of variation, health may persist in virtue of the 
 power of selection, which appertains to the spon- 
 g-ioles of the root in absorbing nutriment; and 
 also as reg-ards lig'ht, from the tendency which most 
 plants have to accommodate themselves to any 
 deficiency of this element, by presenting- their leafy 
 expansion in that direction where the most of its 
 influence may be obtained. But beyond a certain 
 limit an unhealthy condition sets in. If the soil 
 contain not the inorg^anic elements, which are abso- 
 lutely indispensable for the tissues of the plant, 
 or even if they be there and not in a state to be ab- 
 sorbed, a dwindling* and degeneration ensue ; if lig'ht 
 be deficient in quantity, pallor, feebleness, and elon- 
 gation of tissue follow, with more fluidity and 
 general softness of texture. These conditions of 
 plants have their analogues in the ill-fed and ill- 
 nourished children in some of our manufacturing 
 districts ; they are stunted and diseased. Transport 
 a healthy country lad, with the bloom of health on 
 his cheek, from his native hills and valleys, or woods 
 and fields, to the stool behind a desk for eight hours 
 a day, in a narrow street in any city, where the rays 
 of the sun rarely penetrate, it will not be long before 
 
145 
 
 the skin of the animal and the cuticle of the plant 
 may be submitted for comparison, when both will 
 testify to the importance of the solar rays^ as an 
 indispensable agent in supporting* the normal pro- 
 cesses of organic life. So far common observation 
 is competent to a solution of the facts ; but beyond 
 this we come to the enquiry, what resemblances are 
 there in the early conditions of plants and animals. 
 Each originates from nucleated cells, endowed by the 
 All-seeing Power with a blind impulse of pro- 
 gressive development ; the most simple cell of a 
 vegetable multiplies itself by a generation of new 
 cells within it, when the parent dies, and liberates 
 the offspring. Here progression is simply multipli- 
 cation ; it is, as it were, progression in length only. 
 The original cell, however, of animals, which is 
 styled the g^erminal vesicle, extends or becomes 
 developed into dissimilar parts ; and whatever may 
 be the variety, all alike proceed from the original 
 germ cell, and the tout ensemble of parts constitutes 
 the one and indivisible whole ; in this instance 
 there is addition besides multiplication, tissues and 
 organs are added in all variety, until the maximum 
 of organic development is attained in the wonderful 
 being*, man. 
 
 Yet how many points of resemblance are there 
 between the vegetable cell and the fully developed 
 human being, in a physiological and pathological 
 point of view. There must be nourishment to sus- 
 tain both ; both require a certain amount of light 
 
146 
 
 and heat for their g-rowth and increase, and are 
 dependent upon various unknown causes for active 
 and healthy existence; and when a certain time 
 has expired^ all alike return to a condition^ in which 
 the particles composing* them are subject only to the 
 dominion of the laws which preside over inorg'anic 
 matter. 
 
 But during- the existence of plants and animals^ 
 we discover other features of comparison ; plants^ as 
 well as animals^ are liable to disease; they are 
 subject to functional and org-anic affections. The 
 former^ among* plants, are usually traceable to 
 atmospheric vicissitudes or irreg-ularities, changes 
 of situation, &c. ; and in man to irreg*ularities of 
 diet, and mental and bodily excesses, as well as to 
 atmospheric vicissitudes.* 
 
 The org-anic diseases of plants and animals depend 
 upon a repetition, or continuance, of functional de- 
 rangement. As a consequence of this, the nutrition 
 and reproduction of tissues lose their normal and 
 definite character, wherefrom an indefinite and ab- 
 normal result is obtained. There is a hmit to 
 abnormal productions, and they are apparently 
 
 * " Plenck published a treatise on Vegetable Pathology, 
 in which he divided diseases into eight classes : 1. External 
 injuries; 2. Flux of juices; 3. Debility; 4. Cachexies; 5. 
 Putrefactions; 6. Excrescences; 7- Monstrosities; and 8. 
 Sterihty. And he concludes with an enumeration of the 
 animals which injure plants." — Essay on the Diseases of 
 Plants, Gardenei's Chronicle. 
 
147 
 
 subject to laws^ thoug-h not yet understood. In 
 animals^ they may be either excessive development 
 of natural tissue in natural localities^ as obesity and 
 fatty tumours; they may be natural products in 
 unnatural situations^ as fatty deg'enerations of mus- 
 cular tissue ; or altogether new and unnatural pro- 
 ducts^ as tubercle and cancer. 
 
 In plants^ from their greater simplicity of struc- 
 ture^ organic affections are perhaps entirely limited 
 to the two first forms of animal organic disease ; 
 viz. to undue development of tissue in natural 
 situations^ and to the formation of natural tissue in 
 parts of a plant where they are not usually found in 
 a state of nature. The variety of excrescences seen 
 on the stems^ branches^ and twigs of plants^ may be 
 given as instances of the former ; and the conversion 
 of stamina into petals, as in double flowers, as an 
 instance of the latter. 
 
 We derive our sustenance from vegetables, and 
 they from us; they produce for us the soothing 
 opiate and the deadly strychnia ; we for them the 
 animating ammonia, and the distortions and sterility 
 of excessive culture 3 we engender in them, by the 
 latter, debility, disease, and death; and in our 
 turn we become their prey. All this indeed is but 
 a C3^cle of events, that requires no learned mind to 
 fathom, and to comprehend ; it is a matter of every 
 day occurrence, and, thoug-h perhaps not entirely 
 unheeded, is not dwelt upon in the fulness of its 
 bearings and importance. 
 
 L 2 
 
148 
 
 Let us now consider the diseases of plants^ as a 
 study progressive to those of man ; and as their 
 physiolog-y has so extensively served us^ we may 
 possibly also find in their pathology much material 
 for instruction ; not that it will be attempted to shew 
 that the same diseases affect both kingdoms^ but 
 that diseases^ though dissimilar in eifectS; may have 
 similar sources. 
 
 Unfortunately^ there are not many men in this 
 country^ who need go further than their own gar- 
 dens to find abundance of disease among their fruit 
 trees and vegetables. The vine^ the apple and the 
 potato^ common to most gardens^ will furnish speci- 
 mens. 
 
 It is an error of a serious kind to suppose^ that 
 the parasites which infest plants are not essentially 
 the cause^ or^ perhaps^ more properly speakings the 
 elements of disease. I confine myself here to dis- 
 ease of parasitic origin^ as that is the subject of 
 which I am chiefly treating. 
 
 That parasitic growths are the elements of disease 
 in some instances^ is now beyond dispute. The 
 experiments of Mr. Hassall^ detailed in Part II. of 
 the Transactions of the Microscopical Society of 
 London^ are most conclusive 3 and they are of that 
 simple nature^ that any one may convince himself of 
 their accuracy^ by a repetition of them from the 
 directions there laid down. 
 
 He sayS; the decay is communicable at will ^^to 
 any fruits of the apple and peach kind; no matter 
 
149 
 
 how strong" their vital energies may be^ by the simple 
 act of inoculation of the sound fruit with a portion 
 of decayed matter^ containing- filaments of the fungi. 
 We may use with success the sporules of such fung-i ; 
 but in this case the decomposition does not set in so 
 quickly ; in the one case^ the smaller filaments of 
 the fiing-i have advanced several stag-es in their 
 growth 3 while in the other^ the sporules have yet 
 to pass throug-h the several stag-es of their deve- 
 lopment." 
 
 Mr. Hassall^ however^ seems to speak doubtfully 
 as to the mode in which the disease becomes natu- 
 rally introduced ;* how the spores enter the fi'uit^ 
 "is not very clear — thoug-h probably^ it is by 
 insinuating- themselves between the cells of which 
 the cuticle is composed^ or perhaps by means of the 
 stomata^ where they are present. I may here 
 state that the experiments were made on fruity while 
 living-^ and attached to the tree." 
 
 But why should there be a doubt as to the parts 
 by which the sporules of minute fung-i enter the 
 plant, when it is clear, that not only can they enter 
 
 * The Bunt. "This disease appears at the moment of the 
 germination of the plant. The affected individuals are of a 
 dark green, and the stem is discoloured. As the ears are 
 issuing from the sheaths, their stalks are of a dark green^ 
 but very slender. When the ear has fully grown out, its 
 dull, dirty colour, causes it to be immediately distinguished 
 from the healthy ones, and it soon turns white." — Essay 
 on the Diseases of Plants, " 
 
150 
 
 by the spongioles^ but by the stomata of the leaves^ 
 and ming-le with the sap. It is true^ that they 
 make their appearance and grow upon the leaves 
 and the finit; but these are the situations most 
 adapted for their fructification. I have seen the 
 spores of the fungi which attack the cucumber and 
 vegetable-marrow^ in the cells of the hairs^ and 
 even their filamentous prolongations ; these ap- 
 propriate the fluids conveyed to the cells of the 
 hair^ rupture them^ and at length fructify. 
 
 On referring to Dr. Lindley's Medical and Eco- 
 nomic Botany^ I find that many fimgi are the 
 active elements of disease^ and in a manner which 
 renders it highly improbable that they are so in any 
 other way^ than by obtaining an entrance to the sap 
 of the plants. Of the microscopic fungus which 
 destroys wheat^ the Uredo caries of De CandoUe, 
 we find the habitat to be within the ovary of the 
 com^ and that 4^000^000 may be contained in a 
 grain of wheat^ — now this and another fungus^ the 
 Lanosa nivalis^ are said to destroy whole crops of 
 corn: we cannot imagine that such an extensive 
 affection^ can have any other source than by means 
 of the spores through the sap^ seeing that bruising 
 of the surface^ or rupture of the cuticle of the 
 apple^ a comparatively soft fruit is necessary to 
 produce the disease artificially in them 3 besides^ a 
 grain of corn containing vibriones^ when grown and 
 having fruited^ the new fruit also contains them — 
 now here^ as this is I believe almost invariably the 
 
151 
 
 case^ either they or their ova must be carried with 
 the sap to the new germs. 
 
 It is rather a remarkable fact; that these entophytes 
 appropriate the nutriment destined for the plant in 
 which they g-row^ they are consequently the means 
 in many instances of its entire destruction^ though 
 only partially so in others. 
 
 There are many Fungi which have this tendency. 
 The Puccinia gramienis^ ^^ preys upon the juices of 
 plants, and prevents the grain from swelling.'^ 
 The ^cidium urticse^ common on nettles, deprives 
 the plant on which it grows, of the organizable 
 matter, intended for its own nutrition. The 
 Erysiphe communis, overruns and destroys peas. 
 The Botrytis infestans, ^^ attacks the leaves and 
 stems of potatoes.^' The Oidium abortifaciens, 
 attacks the ovaries of grasses — and the Oidium 
 Tuckeri, ^^ a formidable parasite, destroys the 
 functions of the skin, of the parts it attacks.^' The 
 latter has been most injurious to the vines, during 
 the last two years. I have known instances in 
 which the vines have been cut down, and every 
 means taken to rid the houses of the disease ; but 
 this year, it has made its appearance, with all its 
 former virulence, in the new shoots. 
 
 This, however, is sufficient to shew that plants 
 are liable to disease, depending upon parasitic 
 growths, which affect their vital powers, and deprive 
 them of their natural nutritive fluids. 
 
 But somewhat similar diseases belong also to 
 
152 
 
 warm climates ; in a letter from Cuba^ dated Dec, 
 1843^ — Mr. Bastian writes^ '^ a plague has appeared 
 among" the orange trees — a mildew attacking the 
 leaves and the blossoms^ which finally dry up. It 
 most frequently kills the trees. None of the orange 
 family are exempt; lemons^ limes^ and their varieties^ 
 with the shaddock and forbidden fruity have all 
 suffered." This disease has continued without 
 intermission^ till the present year^ — when the same 
 gentleman writes^ Feb. 20th^ 1850: "The evil 
 exist^;^ although in a diminished degree^ so much so, 
 as to have allowed the trees to produce me 30,000 
 oranges again. In old times, the same plantations 
 produced me 100,000.'' 
 
 The West India sugar-canes are also liable to 
 a disease, which the Rev. Mr. Griffiths, in his 
 Natural History of the Island of Barbadoes, speaks 
 of, in the following manner : " This, among- diseases 
 peculiar to canes, as among those which happen 
 to men, too justly claims the horrible precedence.'' 
 This disease is called the Yellow Blast. It is 
 difficult to distinguish the Blast in its infancy, from 
 the effect of dry weather. 
 
 There are often seen on such sickly canes, many 
 small protuberant knobs, of a soft downy substance. 
 It is likewise observable, that such blades will be 
 full of brownish decaying spots. The disease is 
 very destructive to the canes. It is observed, that 
 the Blast usually appears successively in the same 
 fields, and often in the very same spot of land. 
 
153 
 
 This Blast is often found far from ^^ infected places/' 
 and the infection always spreads faster to the 
 leeward^ or with the wind. 
 
 " It is remarkable if canes have been once 
 infected with the Blast^ althoug-h they afterwards to 
 all appearance^ seem to recover ; yet the juice of 
 such canes will neither afford so much sug-ar^ nor so 
 good of its kind^ as if obtained from canes which 
 were never infected." 
 
 I may here allude to the circumstance^ that in 
 the island of Cuba, the destructive mildew is com- 
 monly called, la pesta. 
 
 It were needless to multiply instances of other 
 endemic and epidemic diseases of vegetables ; they 
 are well known by practical observers to be -very 
 numerous, and I believe, in most instances, depend- 
 ing- upon fung-oid gTowths. The destruction of 
 veg*etables by insects, is of a very different nature 
 to that produced by the fiingi ; it would be as 
 unreasonable to consider the consumption of corn 
 and herbag-e by locusts, as a disease of veg-etation, 
 as the massacre and devouring- of human being's by 
 cannibals, a disease of the human body. 
 
 It is true that insects are exceeding-ly destruc- 
 tive to plants, but as far as I am able to obtain 
 information, they appear to be so chiefly by their 
 voracious propensities ) they consume the structure 
 of the plant in its entity, and do not primarily inter- 
 fere with its vitality. The instance of the vibriones, 
 before-mentioned, seems at first to be an exception 
 
154 
 
 to the rule, but this is rather apparent^ than real ; 
 and it may be made to apply more as a confirmation^ 
 than an obstacle to the vegetable theory : for if we 
 may fairly compare the diseases of animals with 
 those of plants^ the existence of entozoa in the lat- 
 ter^ would be considered an essential point to be 
 substantiated. 
 
 Having- now considered the question as to the 
 infeasibility of supposing* that chemical fermentation 
 is the basis upon which a theory of diseases can be 
 sustained; and having' shewn that life is inseparable 
 from infection^ and miasmatic g-eneration -, —having* 
 explained the phenomena of the dispersion of 
 diseases by comparison with the dispersion of plants^ 
 and finally^ having* demonstrated that the physiolog*y 
 and pathology of plants bear so close a relation to 
 each other^ and that their epidemic affections 
 depend upon minute org*anic g*ermS; I submit to the 
 judgement of my readers^ whether there is not much 
 reasonableness in the application of the facts to the 
 inference— that living germs are the cause of epi- 
 demic disease in man and animals. 
 
CHAPTER IV. 
 
 RESULTS IN PROOF OF THE TENABLENESS OF THE 
 PROPOSITION. 
 
 SECTION I. 
 
 OBSERVATIONS ON SOME OF THE LAWS OF EPIDEMIC 
 DISEASES. 
 
 The results obtained by comparmg" certain facts 
 connected with Epidemic Affections of animals^ 
 with analog'ous affections in plants^ afford^ from the 
 few instances I shall here notice^ a very strong- 
 presumption^ that analogous causes operate in the 
 production of these affections. I have already 
 quoted from Hecker^ to shew that previously to^ 
 and during the Epidemics of the Middle Ages^ 
 the minuter forms of animal and vegetable life 
 appeared to be called into existence^ much more 
 abundantly than usual ; that famines prevailed in 
 consequence of failure of cereal crops^ no doubt 
 depending then^ as now^ upon the various forms of 
 ftingiferous gi'owth. I cannot refrain quoting here^ 
 a passage or two from our old friend Virgil • for he 
 confirms not only the fact of peculiar showers in 
 
156 
 
 connexion with diseases^ but he also refers to the 
 rust of corn^ thus : 
 
 150. "Mox et frumentis labor additus; ut mala culmos 
 
 Esset rubigo , . • • 
 
 Intereunt segetes." 
 
 Georg, 1. 
 
 Then : 
 
 311. " Quid tempestates autumni et sidera dicam? 
 
 322. '^ Saepe etiam* immensum coelo venit agmen aquarum 
 Et foedam glomerant tempestatem imbribus atris 
 Collectse ex alto nubes.^' 
 
 Georg, 1. 
 
 The occurrence of black showers in this country 
 has been observed during* the present year^ and I 
 understand that in the fenny countries of the East, 
 the corn has suffered much from the Uredo. I am 
 not mentioning the circumstances as cause and 
 effect, but merely to call attention to the fact, that 
 unusual phenomena of this kind have been generally 
 associated with disease of the animal and vegetable 
 tribes. 
 
 The same causes also predispose plants as well 
 as animals, to epidemic attacks of disease. The 
 repeated observations in the public journals on the 
 subject of ventilation, drainage, and over- crowding, 
 render all notice from me needless, to shew that 
 these, though they do not produce the diseases 
 
 * Vidi understood. 
 
157 
 
 treated of, yet that under the influence of bad air, 
 bad drainage, and over-crowding*, epidemics are 
 fostered and spread. 
 
 Lastly, says the Count Philippo Re, ^^ I would 
 remark that if had cultivation, and especially had 
 drainage, does not produce hunt or smut, it is 
 certain that those Jields, the worst treated ifi these 
 respects, suffer the most from these diseases. ^^ 
 
 It has been remarked by many observers, that a 
 greater fecundity has attended upon Pestilences, 
 and this has been proved by comparison, that the 
 births in proportion have far exceeded the ordinary 
 limit.* In juxtaposition with this observation, I 
 will place the following*, not as a proof, but as a 
 remark made quite independently of the subject of 
 which I am treating*. " From the first the diseased 
 ears are larger than the healthy ones, and are sooner 
 matured. What appears singular, but which I 
 have not, perhaps, sufiiciently verified, is that the 
 seeds are more ahundant than in a sound earP 
 
 * " At the close of the year 1665/' says Dr. Hodges, 
 " even women, before deemed barren, were said to prove 
 prolific.'' 
 
 "After the cessation of the Black Plague, a greater 
 fecundity in women was every where remarkable — a grand 
 phenomenon, which from its occurrence after every de- 
 structive pestilence proves to conviction, if any occurrence 
 can do so, the prevalence of a higher power in the direction 
 of general organic life. Marriages were almost without 
 exception proHfic ; and double and treble births were more 
 frequent than at other times." — Hecker, p. 31. 
 
158 
 
 Now these are facts which require amplification^ 
 and if these two alone should be shewn upon an 
 extensive field of observation^ to apply not only to 
 corn, but to other members of the vegetable king-- 
 dom, as I doubt not will be the case, thoug-h I am 
 not fiilly prepared to prove it, it would be difficult 
 to dissociate the fertility of the two living* king*- 
 doms from the operations of one and the same, or an 
 analog'ous law. 
 
 The epidemic diseases of plants are both infectious 
 and contagious, at times they are observed to be 
 endemic only, and then depending" particularly upon 
 some local causes. This is a law of diseases which 
 applies equally to those of men and animals. In 
 connexion with this law is another, which, as far as I 
 am aware, has not hitherto been noticed in connexion 
 with plants. The potato disease, which excited so 
 much interest and created so much anxiety for the 
 poorer classes of society, led the Government of this 
 country to employ the most learned men to inves- 
 tig-ate the subject, in the hope of propounding- some 
 reasons which should explain the cause of the 
 calamity, and thereby deduce a method of eradi- 
 cating* the evil, or, in other words, discover a cure for 
 the disease. Many were the opinions as to the cause of 
 the distemper, which it were useless here to recount, 
 but a method was sug-g-ested, to which most people, 
 I believe, looked forward with great anticipations, 
 and this was to obtain native seed, and to sow it 
 on virg-in soil. Was the end accomplished ? No. 
 
159 
 
 For thoug-h the seed was sown^ and the plants 
 g-rew^ the disease still appeared among- the newly 
 imported individuals^ to as gi^eat an extent^ as 
 among" the native or domesticated plants. 
 
 As a parallel to this^ it may be stated^ that^ as 
 reg-ards either endemic or epidemic disease^ those 
 persons newly arrived^ either in a district or coun- 
 try where these prevail^ are even more liable to 
 them than the residents.* Ag-ain^ I have learned^ 
 that where the potato disease has been so bad as 
 to render the crop almost valueless^ the best plan to 
 be adopted is^ to allow the plants to remain in the 
 earthy and thus leave such as retain their g-erminating* 
 powers to come up spontaneously the following- 
 year. I certainly saw one larg-e field treated in this 
 way, yield a crop almost without disease. 
 
 * It is stated that on the decline of the Plague, 1665, 
 those who returned early to London, or new comers, were 
 certain to be attacked. In proof of this the 1st week of 
 November, the deaths increased 400, and "physicians 
 reported that above 3000 feU sick that week, mostly new 
 comers.'' 
 
 See also Dr. Copland's Diet. Pract. Med. Epidemic and 
 Endemic Diseases. 
 
 " The hardy mountaineer is a surer victim of paludal 
 fever, whether he visits the low countries of the tropics, or 
 the marshes of a more temperate cUmate, than the feebler 
 native of those countries." — Dr, R. Williams on Morbid 
 Poisons. 
 
IGO 
 
 The seasoning"^ in this instance^ seems to hear 
 a comparison with the seasoning- of animals and 
 man^ under a variety of diseases^ which for a time 
 renders them insusceptible of another attack. It 
 therefore does not appear so improbable^ that these 
 affections may be reg-arded^ as Ung-er^ the German 
 botanist supposed^ the Exanthemata^ or Eruptive 
 Fevers of veg-etables. 
 
 Another feature seems to associate the Epidemics 
 of plants and animals^ in a manner sug-g-estive of 
 analog-ous causes operating- in both instances. 
 
 The lung-s of animals and the leaves of vegetables^ 
 are their respiratory org-ans^ by means of which, 
 the blood in the one case and the sap in the other, 
 derive g-as from the air, and impart g-as to it, each 
 taking- what is thrown off by the other. 
 
 Now the epidemics amon^ veg-etables, have a 
 remarkable tendency to exhibit their effects pri- 
 marily on the leaves, and particularly on those 
 parts which are appropriated to the function of 
 respiration. It is from the stomates that many of 
 the fung-i commence to g-erminate, and their fructi- 
 fication may be seen sprouting- from the opening- 
 composed of a chink, surrounded by a peculiar ar- 
 rang-ement of cells, which constitute the breathing- 
 apparatus of their victim. 
 
 In the earlier epidemics, of which we read, one of 
 the most remarkable circumstances, was the extra- 
 ordinary influence the poisonous matter appeared to 
 
101 
 
 exercise over the lung's^*' and the}' again^ were the 
 means of propag-ating* the disease^ and spreading- 
 the conta^ous particles throug-h the atmosphere, 
 for we read : " Thus did the plag'ue rag-e in Avig*- 
 non for six or eig-ht weeks, and the pestilential 
 breath of the sick, who expectorated blood, caused 
 a terrible contagion far and near, for even the 
 vicinity of those who had fallen ill of plag'ue was 
 certain death y so that parents abandoned their in- 
 fected children, and all the ties of kindred were 
 dissolved."! "The like was seen in Eg-ypt. Here 
 also inflammation of the lung-s was predominant." 
 " Here too the breath of the sick spread a deadly 
 contagion." 
 
 It is more than probable that all infectious matter 
 obtains an entrance to the system throug-h the lung-s. 
 Inspiring- the air containing- the pestilential semina 
 is, indeed, the only plausible explanation of infection ; 
 for thoug-h the skin is indubitably an absorbing- 
 
 * '' Substances presented to the gastro-intestinal sur- 
 faces, are mixed up with various secretions, mucus, saliva, 
 gastric juice, bile, pancreatic liquor, and special exudations 
 from the peculiar glands of each successive section, while 
 aerial poisons, unmixed and unfettered, are apphed at once 
 to a surface on which, behind scarcely a shadow of a film, 
 circulates the blood prepared, by the habitual action of 
 the respiratory function, to absorb almost every vapour, 
 and every odour, which may not be too irritating to pass 
 the gates of the glottis," — Mitchell on Fevers. 
 
 t Hecker on the '' Black Death." 
 
 M 
 
162 
 
 surface^ and capable of taking- up and conveying to 
 the blood any noxious matter applied to it^ yet it is 
 far more probable that the lung-s would effect this 
 process with g-reater rapidity. Then the stomachy 
 the only other absorbing- surface to which extraneous 
 matter can be applied^ is not likely to be the part 
 where the elements of disease would obtain an 
 entrance to the sj^stem^ for many facts prove^ that 
 infectious matter may be swallowed without any 
 injurious consequences^ unless in a very concentrated 
 state. Instances are not easily found of diseased 
 matter having- been swallowed^ except where diseased 
 veg-etables have formed under some combination 
 of circumstances^ a portion of diet.* 
 
 Many facts are on record which prove the power- 
 ful effect of diseased g-rain when made into bread^ 
 and taken for any leng-th time as a principal 
 article of food. The history of Erg-ot of Rye is too 
 fresh in the memor}^ of most people to require more 
 than an allusion here. The stomach had no power 
 over the secale^ its poisonous properties were retained^ 
 after having- been submitted to the dig-estive process^ 
 as was evidenced by the abortions and g-ang-renes it 
 occasioned. 
 
 But diseased wheat is also capable of inducing- 
 
 * The stomach in some cases is no doubt the medium 
 by which some diseases are contracted. It is well known, 
 that in many places the water induces diarrhoea, tlie per- 
 manent residents, however, may not suffer, but all new 
 comers are more or less affected by drinking it. 
 
163 
 
 gangrene^ and it is more than probable^ that many 
 diseases mig-ht be traced to the use of infected grain 
 of various kinds. An interesting- account of a 
 family who lived at Wattisham^ near Stowmarket, 
 in Suffolk, and all of whom suffered more or less 
 from living- on bread made of smutty wheat, may be 
 found in the Philosophical Transactions. The 
 mother of this family and five of the children, con- 
 sisting- of three g-irls and two bo^s, all suffered from 
 g-ang-rene of the extremities ; the father lost the 
 nails from his hands, and had ulceration of two of 
 his fing-ers.* Dr. WooUaston wrote thus in a letter 
 on this case : '^' The corn with which they made 
 their bread was certainly very bad : it Avas wheat 
 that had been cut in a rainy season, and had lain 
 on the g'round till many of the g-rains were black 
 and totally decayed, but many other poor families 
 in the same villag^e made use of the same corn 
 without receiving- any injury from it. One man lost 
 the use of his arm for some time, and still imagines 
 himself that he was afflicted with the same disorder 
 as Downing-'s family." It is not unlikely this 
 was the case, for numbness and loss of power was 
 one of the well marked characters of the disease. 
 
 What other afflictions may be due to diseased 
 vegetation and adulterated articles of food, and what 
 loss of life may accrue from cheap and adulterated 
 
 * " Similar effects have been experienced from the use 
 of mouldy provisions." — Dr» Lindleys Vegetable Kingdom, 
 
 M 2 
 
164 
 
 drug^ and chemicals is hardly yet dreamt of.*" The 
 systematic practice of adulteration of almost every 
 article of diet which comes to table has become a 
 serious question for the leg-islature to consider. 
 Take only the article of milk^ upon which the young- 
 children of larg-e towns and cities^ make their chief 
 meals^ with the addition of bread. How much milk 
 comes into London from the country^ how much 
 is obtained from stall and grain-fed cows in the 
 metropolis^ and how much is said to be consumed^ 
 would be an interesting" calculation. It is pretty 
 well known that a mixture is sold by which a retailer 
 q{ milk may increase his supply by one-third or one- 
 half. It was discovered in Paris that the brains of 
 animals^ when prepared in a particular manner, 
 formed, when mixed with a certain proportion of 
 milk and water, a very fine and deceptive cream ; 
 in that city this system was carried on to a con- 
 siderable extent. I could not help alluding* to these 
 facts while speaking* of diseased g-rain, for who shall 
 say to what extent a miller in a larg-e wslj of busi- 
 ness, may be able to '^ work in," as it is called, a 
 considerable amount of smutty corn in the manu- 
 facture of flour ? Now, as diseased grain is known 
 
 * "Untold numbers die of the diseases produced by 
 scanty and unwholesome food.'' — Sonthey, 
 
 A large^ nay, a most extensive adulteration of flour with 
 plaster of Paris was detected not many years since The 
 flour was supplied by a contractor for the manufacture of 
 biscuits for the navy. 
 
165 
 
 to induce abortion^ it is impossible to tell how small 
 a portion may in some cases produce the effect ^ we 
 may therefore say with Thomas of Malmesbury, 
 " There is no action of man in this life which is not 
 the beginning* of so long" a chain of consequences^ 
 as that no human providence is high enoug'h to g^ive 
 us a prospect to the end."* 
 
 To return, — associated with these observations 
 are other facts of considerable weig-ht. Before and 
 during" pestilences, abortions are more frequent than 
 in ordinary times ; infectious and contag*ious diseases 
 induce abortion ; besides this, and independently of 
 disease, conditions of the atmosphere have been 
 known to exist when abortion has been an epidemic 
 affection ; of this Dr. Copland says, ^^ to certain 
 states of the atmosphere only can be attributed those 
 frequent abortions sometimes observed which have 
 even assumed an epidemic? form, and of which 
 Hippocrates, Fischer, Tessier, Desormeaux, and 
 others have made mention.'^ With this reference I 
 will close the subject of comparison between the 
 affections of the breathing apparatus in animals and 
 plants, merely alluding- to the probability that under 
 some conditions of atmosphere, independently of 
 heat, &c. vegetables without any other assignable 
 cause will become abortive. 
 
 * See Southey's Doctor, vol. ii. interchapter vi. p. 115, 
 for an illustration of this subject. 
 
1G6 
 
 SECTION II. 
 
 WHAT IS THE NATURE OF THOSE POISONS WHICH MOST 
 RESEMBLE THE MORBID POISONS IN THEIR EFFECTS ON 
 THE BODY? 
 
 In the early part of this book^ I considered the 
 nature of poisons generally, and had occasion to 
 remark upon the characters which separated poisons 
 into two distinct classes. Ist^ Those which have 
 the power of self multiplication ; and 2nd^ Those 
 destitute of this property. 
 
 Of the first we have seen that the poisons of 
 epidemic diseases multiply both in and out of the 
 body. 
 
 The poisons of infectious diseases, not usually 
 epidemic, do the same. Those of endemic affections, 
 such as ague and some fevers, usually become mul- 
 tiplied out of the body only, but under some circum- 
 stances, and peculiar atmospheric conditions, they 
 may be also multiplied within the body. The 
 amount of these poisons necessary to produce their 
 specific effects, may be inappreciable. Of the second 
 class, there are two kinds, those derived from the 
 organic kingdom and those derived from the inor- 
 ganic kingdom. Of these, the amount necessary to 
 produce their specific effects is appreciable and pretty 
 well known. 
 
 But among* those poisons, consisting of organic 
 
107 
 
 products^ there is one which seems to hold an inter- 
 mediate place. This is derived from one of the 
 Fung"als^ and as it takes this remarkable position as 
 a link of connexion between the two classes of 
 poisons^ I may be excused quoting* a passage of 
 some leng*th upon this ag-ent^ from Dr. Lindley's 
 Veg-etable Kingdom. " One of the most poisonous 
 of our fung-i^ is the Amanita muscaria^ so called 
 from its power of kilKng- flies^ w hen steeped in milk. 
 Even this is eaten in Kamchatka^ with no other 
 than intoxicating- effects^ according" to the following- 
 account by Lang'sdorf, as translated by Greville. 
 This variety of Amanita muscaria^ is used by the 
 inhabitants of the north-eastern parts of Asia in the 
 same manner as wine^ brandy^ arrack^ opium^ &c. 
 is by other nations." — " The most sing-ular effect of 
 the amanita is the influence it possesses over the 
 urine. It is said^ that from time immemorial^ the 
 inhabitants have known that the fung-us imparts an 
 intoxicating- quality to that secretion^ which con- 
 tinues for a considerable time after taking it. For 
 instance^ a man moderately intoxicated to-day _, will 
 by the next morning- have slept himself sober^ but 
 (as is the custom) by taking- a teacup of his urine, 
 he will be 7nore powerfully intoxicated than he was 
 the preceding- day. It is, therefore, not uncommon 
 for confirmed drunkards to preserve their urine, as 
 a precious liquor against a scarcity of the fungus. 
 The intoxicating property of the urine is capable of 
 
168 
 
 being propagated ; for every one who partakes of it 
 has his urine similarly affected. Thus with a very 
 few amanitae^ a party of drunkards may keep up 
 their debauch for a week/^ 
 
 This property of the amanita^ at once places it in 
 a separate category from all other organic poisons^ 
 it has yet to be shewn upon what this intoxicating- 
 fungus depends for its activity. Whether some 
 secretion is formed in the tissue of the plant^ or 
 whether some new arrangement of the particles of 
 matter or modification of the sporules^ is brought 
 about by entering the system^ it is impossible to 
 say. Langsdorf states that the small deep-coloured 
 specimens of amanita^ and thickly covered with warts, 
 are said to be more powerful than those of a larger 
 size and paler colour. As the effect is not produced 
 until fi-om one to two hours after swallowing the 
 bolus, and as a pleasant intoxication may be ob- 
 tained by this agent for a whole day, and from one 
 dose only, there is a defined line between this and 
 the ordinary narcotics and stimulants in common 
 use. That the digestive powers of the stomach have 
 no influence over the intoxicating properties of the 
 plant, is manifested in the fact, that the active 
 principle passes into the urine, not only not deterio- 
 rated but apparently increased, for, as we have seen, 
 a teacup of the urine from a man, intoxicated by 
 taking the amanita into his stomach, will cause him 
 to be more powerfully intoxicated than by the 
 
169 
 
 orig-inal dose. We have^ therefore, but two con- 
 jectures left for consideration, either the original 
 intoxicating principle is excreted from the system 
 in a condensed form, in which case its indestructi- 
 bility by dig-estion, makes it approach the ordinary 
 org-anic poisons, or there must be an increase of the 
 toxic agent, in which case we must suppose a 
 reproductive process having taken place in the 
 system. " There is," says Dr. Mitchell, " in the 
 wild regions of our western country, a disease called 
 the inilk sickness^ the trembles^ the tires^ the slows, 
 the stiffs-Joints, the pulling fever, ^cP The animals 
 affected with this disease, " stray irregularly, appa- 
 rently without motive 5'' they lose their power of 
 attention, and finally tremble, stagger, and die. 
 '^ When other animals — men, dogs, cats, poultry, 
 crows, buzzards, and hogs, drink the milk or eat the 
 flesh of a diseased cow, they suffer in a somewhat 
 similar manner." This disease is attributed by Dr. 
 Mitchell to the animals having grazed on pasture 
 contaminated with mildew, and the resemblance to 
 the effects of the amanita, together with the per- 
 sistence of the specific principle within the fluids 
 and tissues of the body, render it more than pro- 
 bable that to some fungoid growth, is due the 
 peculiar toxic effects here noticed. Further : '' The 
 animals made sick by the beef of the first one, have 
 been in their turn the cause of a like affection in 
 others ; so that three or four have thus fallen vic- 
 tims successively." De Graaf states, that butter 
 
170 
 
 made from the milk of diseased cows^ tlioug-h heated 
 until it caug-ht fire^ did not lose its deleterious pro- 
 perties. The urine of diseased animals^ collected 
 and reduced by evaporation^ produced the charac- 
 teristic s^^mptoms. All these facts point to some 
 peculiarity in the properties of matter not yet 
 investigated or at least not explained. If we may 
 assume that reproduction is here an element of the 
 persistence and apparent multiplication of active 
 matter^ I know only of one instance to compare 
 with it. A gentleman about to deliver a lecture on 
 the properties of arsenic^ and its history g-enerally, 
 made two solutions of a given quantity of arsenious 
 acid^ in the following manner. He took a certain 
 amount of distilled water^ and the same of filtered 
 Thames water^ and made his solutions of arsenic 
 by separate boiling-s^ he then as soon as possible 
 placed the liquids in identical bottles, carefully pre- 
 pared for their reception. In the one which con- 
 tained the arsenic boiled in river water^ the 
 hyg-rocrocis is now g'rowing*^ while that boiled in 
 distilled water remains perfectly limpid and free 
 from any veg-etable production. There can scarcely 
 be a doubt^ that the filtration of river water was 
 not sufficiently purif3dng- to remove the minute 
 spores of some lower forms of veg-etation^ which not 
 only live in arsenic but have resisted the temperature 
 employed in boiling- an arsenical solution to satu- 
 ration. 
 
 As to the first class^ or truly reproductive and 
 
171 
 
 morbid poisons, the most heterog'enous ideas have 
 from all time existed. I have introduced the notice 
 of the above poisons^ viz. the Amanita^ and that 
 which engenders the milk sickness, to compare the 
 results of the morbid poisons on the human body 
 with them^ and also to associate them with the 
 effects of diseased grain. From the Amanita and 
 that other fung-oid matter which is said to produce 
 the milk sickness, there appears to be a purely toxic 
 action on the system, but in the instance of diseased 
 grain, a blood disease, ending in gangrene, or a 
 specific and peculiar action of the generative organs 
 is the consequence, and w^here the latter occurs, the 
 poison usually expends itself on these parts, either 
 by inducing abortion, or augmenting the catamenial 
 secretion. 
 
 Now, the morbid poisons, if studied only in their 
 results^ shew that there is a combination of these two 
 actions. There is usually, in the first place, a toxic 
 or poisonous action, and secondly, a deteriorating* or 
 decomposing action on the blood, by which there is 
 a tendency to low or asthenic inflammation and gan- 
 grene. It matters not what form of fever we take 
 as an illustration, whether intermittent, pestilential, 
 or exanthematous, either will serve the purpose of 
 shewing how completely the effects of vegetable 
 organic poisons resemble those which for the sake 
 of distinction (I suppose) have been denominated 
 Morbid Poisons. 
 
 Take an attack from the paludal poison. It is 
 
172 
 
 usually ushered in with head-ache^ weariness^ pains 
 in the limbs^ and thirsty with other symptoms ; all 
 these are indicative of a poisonous agent in the 
 blood : then come the full phenomena of the disease 
 at a long-er or shorter interval^ and tending* ulti- 
 mately to destroy some organ of the body. The 
 mind suffers dming* the course of the attack^ and 
 delirium occasionally happens. In severe cases of 
 this disease^ which were more frequent formerly 
 than now^ coma^ delirium^ and frenzy were observed 
 at the commencement of the attack^ and a tendency 
 to rapid disorg*anization of one or several of the 
 viscera. 
 
 If we take the effects of poison of Erysipelas^ of 
 Scarlet Fever^ or Plag'ue^ in each we find at the on- 
 set more or less g*eneral derang-ement of the system^ 
 usually with cerebral disturbance and disordered 
 action of all the dynamic forces of the body^ which 
 clearly indicate the action of a poison j then^ unless 
 some favourable symptoms arise^ the blood exhibits 
 a steady advance towards disorg'anization^ and spha- 
 celation of one or more tissues or parts of the body 
 ensues. In Erysipelas the force of the diseased 
 action is expended on the skin^ and subcutaneous 
 cellular tissue ^ in Scarlet Fever the fauces ulcerate, 
 and slough and the parotids suppurate ', in the 
 Plague there is a general tendency to putrefaction^ 
 and the formation of glandular abscesses with 
 sphacelas. Without going any further into this 
 mattery for my present intention is merely to draw 
 
173 
 
 notice to certain facts^ let me now ask, whether or 
 not, do the poisons of the Ergot, the Uredo, and 
 the Amanita, exhibit more analog-y in their action 
 on the nervous system, the blood and the tissues, 
 than any other poisonous agents with which we are 
 acquainted ? If the whole range of the lower fungi 
 could be examined in reference to their operation on 
 the blood, as decomposers of organic compounds, — if 
 experiments could be made, by which the properties 
 of fungoid matter could be detected, I would ven- 
 ture to say the whole of the phenomena of these 
 diseases could be readily comprehended and their 
 intricacies unravelled. 
 
 We know that the fungi are poisonous, that at 
 times and seasons, and under variations of climate, 
 they vary in their effects, and perhaps lose alto- 
 gether these properties. We know that the fungi 
 produce gangrene of the tissues, and disorganization 
 of the blood ; we know that their spores pervade 
 the atmosphere, and are ready, under favouring- 
 conditions, to increase and multiply • we know that 
 they are ubiquitous, and that those conditions 
 most favourable to their development, are exactly 
 such as are proved to foster and engender disease, 
 and above all, they have been proved to be the ele- 
 ments of some diseases in man, in animals, and in 
 plants. Can as much be said of any other known 
 agents, animate or inanimate, comprised in our cate- 
 gory ? 
 
 It has been said, we do not see after death, —the 
 
174 
 
 interlacing* mycilium^ or the sprouting* pileus; 
 therefore the fung-i are not the ag-ents of disease— it 
 has been said that carbonic acid and alcohol are 
 not found as products of diseased action— conse- 
 quently disease is not a fermentative process. '^ In 
 all cases/' says Liebig*^ '' where the strictest investi- 
 g-ation has failed to demonstrate the presence of 
 org-anic being's in the contagion of a miasm^ or 
 contag-ious disease^ the hypothesis that such being-s 
 have cooperated^ or do cooperate in the morbid 
 process^ must be rejected as totally void of founda- 
 tion and support." Much as I admire the genius 
 of this g'reat man^ it is difficult to refrain from 
 remarking"^ that I doubt if any of his g'reat 
 discoveries would have been made^ if^ in the first 
 instance^ hypotheses had not formed the basis of 
 all his researches. It has been said^ " that casual 
 conjunctions in chemistry^ gave us most of our 
 valuable discoveries :" and it is from casual con- 
 junctions that hypotheses are usually formed^ the 
 working- out proves either their fallacy or their 
 truth^ but to say that an hypothesis has no founda- 
 tion^ until demonstrated to be true^ is rather 
 knocking- down arg-ument. And who^ let me ask^ 
 has been more prolific of hypotheses than our 
 continental neig-hbour ? Yet he^ according- to his 
 mode of reasoning-^ would sweep away all such 
 words from the vocabularies of philosophers. What 
 foundation has the chemical hypothesis of disease^ 
 when it fails to explain the most important element 
 
175 
 
 of contag-iou^ and infectious diseases : viz. the 
 reproductive property of their g-erms ? 
 
 It is perhaps necessary to say something- in ex- 
 planation of the sudden deaths arising- from morbid 
 poisons. They may occur from two causes. One 
 being- the result of a concentrated amount of poison 
 g-erms being- inhaled into the lungs^ and acting- as 
 an ordinary toxic ag-ent ; and the other^ which I 
 put only hypothetically^ the consequence of the 
 rapid evolution of g-as in the vessels arising- from a 
 sudden decomposition of bloody as it passes through 
 the lung-s. The only authority I have for this 
 supposition, is the fact that the blood after death, 
 from pestilential affections, is found to be far 
 advanced towards decomposition ; that in Paris 
 last year, two patients were bled while suffering- 
 fl'om Cholera, and with the small quantity of blood 
 which floAved, bubbles of air also escaped :* and be- 
 sides this, it was demonstrated by Mr. Herapath, that 
 ammonia was ^ven off from Cholera patients, both 
 by the lung-s and skin. These facts, though they 
 are not conclusive, nevertheless render it probable 
 that such an explanation is not entirely out of 
 reason— especially too, when we know how fatal 
 are the effects of uncombined air, when it enters the 
 vessels near to the heart. 
 
 * Both these patients died. 
 
176 
 
 SECTION III. 
 
 WHAT RESULTS DO WE OBTAIN FROM THE EFFECTS OF RE- 
 MEDIAL AGENTS, IN PROOF OF THE HYPOTHESIS ? 
 
 I HAVE here used the word hypothesis^ because^ 
 having- so far advanced in the enquiry^ I trust suf- 
 ficient has been said to render the term apphcable. 
 
 Under the term remedial agents^ I shall include 
 all those causes, whether natural or artificial, which 
 tend to neutralize or destroy the germs of infection, 
 or miasmatic poison, whether this be effected out of 
 or within the body. 
 
 First, then, let us consider the results of drainag-e 
 and cultivation in removing* the causes of endemic 
 disease. One well authenticated case is as g-ood as 
 a thousand. I will take one, which, fi'om its source, 
 will be received as unexceptionable ; and from its 
 association with a very learned and amusing- book, 
 will be accepted as an ag-reeable reminder of the 
 many pleasant hours spent in the perusal of the 
 poet Southey's ^^ Doctor .'' 
 
 '' Doncaster is built upon a peninsula, or ridg-e 
 of land, about a mile across, having- a gentle slope 
 from east to west, and bounded on the west by the 
 river ; this ridg-e is composed of three strata ', to wit, 
 of the alluvial soil deposited by the river in former 
 
177 
 
 ag'es^ and of limestone on the north and west ; and 
 of sandstone to the south and east. To the south of 
 this neck of land, lies a tract called Potteric Carr^ 
 which is much below the level of the river, and was 
 a morass^ or rang*e of fens when our Doctor first 
 took up his abode in Doncaster. This tract extends 
 about four miles in leng*th^ and nearly three in 
 breadth^ and the security which it afforded ag-ainst 
 an attack on that side^ while the river protected the 
 peninsula by its semicircular bend on the other, 
 was evidently one reason why the Romans fixed 
 upon the site of Doncaster for a station. In 
 Brockett's Glossary of North Country words, Carr 
 is interpreted to mean ' flat marshy land/ ' a pool 
 or lake / but the etymolog-y of the word is yet to be 
 discovered. 
 
 '' These fens were drained and enclosed pursuant 
 to an Act of Parliament, which was obtained for that 
 purpose in the year 17 06. Three principal drains 
 were then cut, fourteen feet wide, and about four 
 miles long", into which the water was conducted 
 from every part of the Carr southward, to the little 
 river Torne, at Rossing'ton Bridg^e, whence it flows 
 into the Trent. Before these draining-s, the g^round 
 was liable to frequent inundations j and about the 
 centre there was a decoy for wild ducks ^ there is 
 still a deep water there of considerable extent, in 
 which very larg-e pike and eels are found. The soil, 
 which was so bog'gy at first that horses were lost in 
 attempting- to drink at the drains, has been brought 
 
 N 
 
178 
 
 into good cultivation^ (as all such g-round may be) 
 to the g'reat improvement of the district; for till 
 this improvement was effected^ intermittent fevers 
 and sore throats were j^revalent there, and they have 
 ceased from the time the land was drained. The 
 most unhealthy season now^ is the spring*^ when 
 cold winds^ from the north and north-east^ usually 
 prevail during- some six weeks 5 at other times Don- 
 caster is considered to he a healthy place. It has 
 been observed that when endemic (?) diseases arrive 
 there^ they uniformly come from the south; and 
 that the state of the weather may be foretold from a 
 knowledg"e of what it has been at a g'iven time in 
 London^ making* an allowance of about three days^ 
 for the chance of winds. Here^ as in all places 
 which lie upon a g'reat and frequented road^ the 
 transmission of disease has been greatly facilitated 
 by the increase of travelling".^^ 
 
 I feel certain of being* excused for transcribing* 
 this long* passag-e from Southey. It would have 
 been impossible to convey its whole meaning* with- 
 out giving* it entire. The continuation of the 
 chapter is no less instructive and applicable to our 
 subject^ though more particularly so to an extension 
 of the enquiry. The sore throats and intermittents^ 
 from which Doncaster has been freed^ by the drainage 
 of Potteric Carr^ informs us at once that decom- 
 posing matter is the material by which the poison 
 of fever is vivified and sustained^ the wet and boggy 
 state of the soil is just the condition^ when no 
 drainage exists^ to bring into activity the germs of 
 
179 
 
 disease^ which otherwise would lie latent. So satis- 
 fied and acquainted are we with the elements 
 necessary for the production of fever^ that we mig-ht 
 as certainly brin^ about an endemic intermittent 
 by forming- an artificial bog-^ as we could be sure of 
 g-rowing* mushrooms by making' a bed in the manner 
 laid down by g-ardeners for this purpose. Dr. 
 Lindley also says^ ^' the Polyporus fomentarius has 
 been artificially produced in Germany^ but merely 
 by placing' w^ood in a favourable situation, and keep- 
 ing- it well moistened. Five or six crops were 
 obtained in the year.'' 
 
 Let warmth, moisture, darkness, and decaying 
 matter be given, and inanimate disintegrated par- 
 ticles will soon be converted into definite forms and 
 combinations instinct ^vdth life. It is by the unseen 
 forms of living- being-s, that the atmosphere is pre- 
 served from becoming- charg-ed with deadly g-ases ; 
 they take the first rank in the great scheme of 
 animated being's, the plant first, and then the animal. 
 ^^ Let the earth bring- forth grass/' ^^ Let there be 
 lights in the firmament." ^^ Let the waters bring forth 
 the moving creature, and fowl that may fly," and 
 ^^Let the earth bring forth the cattle, the creeping 
 thing, and the beast." This is the order of crea- 
 tion, of living things, and the earth was prepared by 
 vegetation for the animal world. The work of conver- 
 sion is accomplished by vegetation ; and this is con- 
 sumed for the construction of higher organizations. 
 
 The laws which govern and control the universe; 
 
 N 2 
 
180 
 
 are as definite and as wonderful among- invisible 
 atoms^ as those which regulate the enormous masses 
 floating* in space 3 and the time will come when the 
 advancing" intellect of man will measure and weig-h 
 the morbid poisons^ as he measures and weighs the 
 stars. Why should the laws of Epidemics be less 
 understood; than the laws which govern the course 
 of comets ? The aspirations of man have led him to 
 penetrate the heavens^ which charm and inspire 
 him y he studies rather the more violent disturbing 
 elements of nature^ the thunder-cloud and the fire 
 of heaven^ than the silent pestilence which steals 
 over the earth. I cannot conceive it possible that 
 the Intellects^ which are occupied in procuring means 
 for the Majesty of this empire to issue her mandates 
 with the velocity of a spirit to the nethermost parts 
 of the earth; should be incapable of solving so deeply 
 interesting a mystery as the causes and nature of 
 pestilential diseases. It would seem that man pre- 
 fers to issue a mandate of destruction many thousand 
 miles distant; than to disarm the pestilence at his 
 door. It is barely a century since Galvani observed 
 the twitchings in the muscles of a frog^s leg; and the 
 batter}^; still named after hini; has already become 
 an agent of instantaneous communication between 
 places many miles distant. But how many centuries 
 have passed away; each one succeeding the other; 
 with its millions of victims to epidemics? And 
 where are the remedies for the evils ? Drainage and 
 cleanliness; with all their advantages; were better 
 understood and more fully carried out by the ancient 
 
181 
 
 Homans than by ourselves ^ there are monuments^ 
 thoug-h crumbling- to decay^ to tell us of the vast en- 
 terprise of these people and of the value they set upon 
 a healthy and vig-orous constitution^ and how well 
 they understood the means of Avarding* oft' disease. 
 
 Cultivation and drainag-e are now fully understood 
 to be the basis by which a healthy condition of air 
 is to be obtained^ next to that^ cleanliness and venti- 
 lation ; if either be neglected a sickly^ mouldy^ and 
 unwholesome contamination of atmosphere ensues ; 
 the odour of a bog* is proverbially mouldy^ and so is 
 that of an ill-ventilated house or cellar ^ dryness^ or 
 the fresh pleasant scent of clean water^ are the 
 antag-onists of these , the aromatic odours of vegfeta- 
 tion are opponents of putrefaction^ and consequently 
 of the development of the lower forms of life. All 
 empyreumatic matters prevent mouldiness and de- 
 composition; and odours arrest and prevent the 
 g-rowth of mouldiness. The oil of birch^ with which 
 the Russia leather is impreg-nated^ and which g-ives 
 it so pleasant an odour^ effectually prevents mouldi- 
 ness^ and consequently decay. 
 
 Lindley says^ ^^ It is a most remarkable circum- 
 stance^ and one which deserves particular enquiry , 
 that the g-rowth of the minute fungi^ which con- 
 stitute what is called mouldiness^ is effectually 
 prevented by any kind of perfume."* Cedar has 
 
 * " A good part of the clove trees which grew so plen- 
 tiftdly in the island of Ternate, being feUed at the sohcita- 
 tion of the Dutch, in order to heighten the price of that 
 
182 
 
 been used^ from time immemorial^ for a like purpose 5 
 and I doubt not the recommendation of Virgil^ 
 before quoted^ in reference to the burning* of cedar, 
 was founded on some practical utility of this kind, 
 though its modus operandi was unknown to him. 
 Allied to these is a curious circumstance, and worthy 
 attention. I copy the following* from an old work 
 on Pestilences. '' It is remarkable that when the 
 Plague raged in London, Bucklersbury, which stood 
 in the very heart of the city, was free from that dis- 
 temper 5 the reason given for it is, that it was chiefly 
 inhabited by diniggists and apothecaries, the scent 
 of whose drugs kept away the infection, which were 
 so unnatural to the pestilential insects, that they 
 were killed or driven away by the strong smell of 
 some sorts of them.'^ " The smell of rue^ and the 
 smoke of tobacco, were prescribed as remedies 
 against the infection ^ but especially tar and pitch 
 barrels, which it was imagined preserved Limehouse, 
 and some of the dock-yards from infection.''* 
 
 Pitch and tar dealers are everywhere spoken of 
 as being remarkably exempt from infectious diseases. 
 
 Cold infusion of tar was used in our colonies as 
 9* prophylactic against the Small Pox. Bishop 
 
 fruit, such a change ensned in the air, as shewed the salw 
 tary effect of the effluvia of clove trees and their blossoms ; 
 the whole island, soon after they were cut down, hecoming 
 exceeding sichly.*^ 
 
 * The observation is originally taken from the City 
 Remembrancer, 133. \ 
 
183 
 
 Berkeley was induced to try it when this disease 
 rag-ed in his neig-hbourhood. The trial fully 
 answered expectation— for all those who took tar- 
 water^ either escaped the disease^ or had it very 
 slig'htly. 
 
 Tan yards and places in the immediate vicinity^ 
 are said to be free from pestilences. The tanners 
 of Bermondsey are said to have escaped the Plag-ue 
 of London^ and one person only died in Gutter 
 Lane^ where was a tan yard. The tanners of Rome 
 are also stated to have been free from Plag-ue. 
 Dr. McLean refers to the exemption of tanners at 
 Cairo. Tannin is prejudicial to most vegetables^ — 
 but Dr. Lindley says it is not always so to ftmgi. 
 ^^ A species of Rhizomorpha is often developed in 
 tan pits." I should imagine that neither plants 
 nor insects would be found very abundantly^ where 
 tannin prevails ; yet we find that the g-all-nut is 
 formed for the protection of an insect from injury 
 by weather^ and as a temporary means of sus- 
 tenance. 
 
 The custom of fiimig-ating with odoriferous sub- 
 stanceS; does not therefore appear upon this view of 
 the matter to be destitute of importance ; indeed^ 
 the universal practice stamps it at once, as an effi- 
 cacious remedy for the purposes of disinfection. 
 The introduction of chlorine fumig-ation, seems to 
 have superseded, in a great measure, the use of 
 frag-rant herbs and woods y and it is questionable 
 whether the substitution be altogether desirable or 
 
184 
 
 advantageous. Many scents may be agreeably 
 and usefully employed, with much less chance of 
 anno3^ance to the patient, and considerably less 
 injury to articles of furniture, &c. 
 
 The fumigations of sulphurous acid and chlorine 
 are, perhaps, more adapted as disinfectants in 
 uninhabited apartments^— their power to destroy 
 vegetation, is well known. They have been used, 
 chiefly, with the idea of neutralizing gaseous exha- 
 lations, particularly chlorine, as it tends to combine 
 with hydrogen, to form hydrochloric acid, and then 
 to unite with ammoniacal matters, forming hydro- 
 chlorate of ammonia. This, supposing noxious or 
 pestilential effluvia consisted of the ammoniacal 
 exudations variously combined, was an exceedingly 
 eflicacious method of rendering them inert; but 
 as we feel convinced that no ammoniacal compound 
 could possibly be the cause of infection, we must 
 look to the influence these gases possess over other 
 forms of matter, and as they are so destructive, 
 even in minute quantities, to vegetable existence, it 
 is possible that their beneficial effects may be due 
 to this property. The immediate neighbourhood of 
 gas works is prejudicial to vegetation, I imagine, 
 from the amount of sulphurous vapours, and to this 
 has been attributed the exemption of persons 
 employed in these works. Many other instances 
 might be cited of a similar nature. 
 
 I have now to speak of medicinal agents, and 
 here comes a considerable diflicultv. 
 
185 
 
 If we mig-ht believe all that has been written on 
 the sure and certain remedies for the ^^ ills that man 
 is heir to/' we should be led to acknowledg-e that 
 both nature and art were prodig-al in antidotes and 
 specifics. The all-bountiful hand of nature^ I do not 
 doubt^ has at the same time scattered the seeds of 
 good and of evil. The fertilizing- showers fall to 
 irrig-ate the soil^ and produce food and nourishment 
 to man; here and there is the reeking* morass 
 " feeding" unnatural veg-etation/' and if man takes 
 up his abode in its vicinity^ the rains which made it 
 unhealthy, have also made it highly fertile ; by 
 labour and cultivation he may convert the mephitic 
 bog* into a waving corn-field, and the seeds of life 
 and sustenance be made to supplant the seeds of 
 death and corruption. 
 
 It is generally believed, that where there are 
 particular and specific diseases, there also may be 
 found appropriate and specific remedies; the 
 discoveries of chemistry, it is not improbable, may in 
 some respects have retarded the progress of natural 
 medicine. In the early ages of the world, the 
 ^^ healing plant'' must have formed the staple of 
 medical commerce, for though Tubal Cain* has been 
 considered as the first surgical instrument maker, 
 because he was the first artificer in brass and iron, 
 we have not discovered that chemical compounds 
 entered hito the composition of physic, till very 
 
 * See Hamiltou's History of MedicinCj vol. i. p. 4. 
 
186 
 
 many years after his time. To the alchemists we 
 owe the science of chemistry^ and much of the 
 physic of the present day may be traced to them. 
 The multiphcity of ingredients which at one time 
 entered into the composition of one dose of physic 
 could only be spoken of under the title of '' legion." 
 Who shall specify the active and curative ingredient 
 (if there be one)^ when from five to a hundred may 
 have been exhibited at the same time ? It has been 
 the pride of our physicians^ that the pharmacopoeia 
 has been simplified ) it has not reached its most 
 simple form yet. That many simple plants have 
 specific and wonderful power over disease^ is an 
 indubitable fact^ but I firmly believe that the 
 laudable^ though mistaken efforts of physicians to 
 improve their effect by various combinations^ have 
 been the means of throwing many valuable medicines 
 into oblivion ; I must also add^ that cheap physic 
 and adulterations have had no small share too in 
 the banishment of much valuable physic from 
 ordinary practice. It has been beheved^ and I think 
 with much reason^ that a thorough search into the 
 qualities of plants^ would shew that ^^they are capable 
 of affording not only great relief, but also effectual 
 and specific remedies." '' That they are not already 
 found^ is rather an argument that we have not been 
 sufficiently inquisitive, than that there are no such 
 plants endued with these virtues." 
 
 Of the result obtained by medical treatment^ in 
 cases of epidemic or infectious disease^ it is most 
 
187 
 
 difficult to speak^ but as my province here is only 
 to shew that living g-erms are the morbific agents^ 
 I have but to refer to such remedies as have been most 
 extolled in controlling- these affections. The disin- 
 fectants have already been mentioned in a cursory 
 manner. An enumeration only of simple medicines 
 used during" the late Epidemic^ shall conclude this 
 work^ as the treatment in former times could not by 
 any possibility furnish satisfactory information. 
 Aromatics and frag-rant stimulants have in all 
 times taken the foremost rank with acids^ such as 
 vineg-ar^ lime and lemon juice. Mr. Guthrie's adop- 
 tion of lemon juice in preference to bark^ which he 
 said made him worse while suffering- from an attack 
 of fever^ during- the Peninsular campaig-n^ and his 
 speedy recovery from the disease^ thoug'h not from 
 its effects^ shews^ when many others can bear equal 
 testimony to its value^ that such a remedy thoug'h 
 simple is not to be despised. 
 
 But to the late Epidemic. Dr. Stevens' saline 
 treatment^ appears^ on the whole^ to have been the 
 most successful. Common salt was used both 
 medically and dietetically^ and formed the gTeatest 
 bulk of the medicine employed. Chlorate of potash 
 and carbonate of soda were added to the medicine. 
 
 The nitro-hydrochloric acid was used with success 
 at St. Thomas's Hospital. 
 
 Dr. Copland used chlorate of potash^ bicarb, soda, 
 hydrochloric, ether, and camphor water. 
 
 Dr. Ayre's calomel treatment had as many, if 
 
188 
 
 not more^ opponents than advocates. Phosphorus 
 had several advocates. 
 
 Creasote and camphor were lauded by some. 
 The beneficial operation of all these remedies mig-ht 
 be explained on the theory here supposed^ that 
 living" g-erms are the cause of Epidemic disease^ but 
 the specific action of any one remedy has not yet 
 had sufiicient attention or trial to enable me to 
 make any deductions of a satisfactory or conclusive 
 nature. 
 
 In the uncertainty which g-enerally prevailed as 
 to the best method of treating* Cholera patients, 
 I was induced (for reasons stated in a pamphlet 
 published last year) to try the efficacy of sulphur, 
 which had been extolled as a specific. In its effects 
 I was not disappointed , but as the results are al« 
 ready before the public, I need not do more than 
 refer to it among- other remedies. 
 
 I did not contemplate even alluding* to this sub- 
 ject, as it would extend far beyond my intended 
 limits. This portion of the enquiry would be more 
 properly carried out by keeping* records of cases, 
 treated in accordance with the view attempted to be 
 established, and I have not the slig-htest hesitation 
 in sa^dng*, that the most ample success would ulti- 
 mately attend a well directed practice, based upon 
 the principles inculcated in these pag*es. 
 
189 
 
 CONCLUSION. 
 
 In making- the foreg-oing* sketchy I have attempted 
 to put tog-ether some ideas on a subject^ which has 
 for the last few years been a theme for meditation 
 in ^leisure hours, viz. What are the causes of Epi- 
 demic, Endemic, and Infectious Diseases? The 
 occurrence of Epidemic Cholera last year in this 
 country, awakened a spirit of enquiry. Where 
 there is unrest, whatever may be the cause, there 
 also is disquiet and discontent. When the oracles 
 of the ag*e were consulted in the emerg-ency, the 
 discordant answers perplexed and confused the 
 anxious searcher after truth. In the spring" of last 
 year, when the enemy was approaching*, unseen 
 and unheard, and the thousands of unconscious 
 victims, who are now lying* in their graves, were 
 faithfully trusting* and fully relying* on the heads 
 of our profession, and the resources of our art, what 
 was the state of our defences, and what the 
 nature or character of our resistance ? One con- 
 siderable body of men would discharg*e from a 
 little tube of g'lass, a host of almost invisible g*lo- 
 bular atoms of sug*ar, said to be as potent and 
 inscrutably operative as the unseen enemy. These 
 infinitesimal practitioners assured the people that 
 they " had powerful means of subduing the disease,^ 
 
190 
 
 but even they differed among' themselves^ though 
 they carried out to the fullest extent the doctrine of 
 their leader^ similia similibus^ which, we may suppose 
 to refer in this case to the minuteness of the opposing- 
 armamenta. Without^ however^ ag-reeing* with this 
 school, I may quote a passage from Dr. Curie, 
 which is, alas ! too true : ^^ We have shewn, as 
 they must (allopathists), and many of them do 
 acknowledge, that they have no fixed basis, no 
 natural law upon which their treatment rests/' 
 
 Who can deny the force of this observation? 
 Sheltered by a principle, it matters not how falla- 
 cious, a man is placed as behind a barrier. If 
 with any reason it could be shewn that the in- 
 finitesimal doses, could by no possibility effect a 
 cure in Cholera , if it could be demonstrated by any 
 line of argument, that a poison, a living poison, 
 circulates with the blood, or lodges in the tissues, 
 the homseopathist must fall ; his " electricity and 
 mineral magnetism,'' and ^^ powerful concentration 
 of life porcer towards the digestive canal^^ will stand 
 for what they are worth. That minute doses of 
 medicine can exert an active influence over the 
 body is not to be denied, but these must consist of 
 powerful drugs, as arnica, aconite, and nux vomica, 
 with others, and it is more than probable, that of 
 such medicines, an inconceivably small amount may 
 produce a specific effect upon some portion of the 
 organic nervous system. 
 
 How is it that a dose of nitre or digitalis, '' can 
 
191 
 
 convert cheerfulness into low spirits/' or a grain of 
 red suliDliuret of antimonj^^ " excite warmth and 
 lively spirits ?''* 
 
 Why should indigo dyers become melancholy, 
 and scarlet dyers choleric ?t We do not know. 
 But there is one thing* we most certainly do know, 
 that a poison may be disarmed by an antidote, and 
 the amount of the latter must be in proportion to 
 that of the former, and as epidemic and contagious 
 diseases do most unquestionably depend upon poi^ 
 sons of a specific nature, and of great amount and 
 activity, an infinitesimal remedy, however it may 
 claim to direct and control the organic forces, 
 under slight and ordinary disturbances, can be no 
 more effectual in destroying the poison of fever, or 
 small pox, than in neutralizing arsenic or prussic 
 acid. 
 
 The uncertainty which generally prevails as to 
 the treatment of Epidemic diseases. Fevers, &c. in- 
 duced me to put together the notions which are 
 contained in these pages, in the hope of leading to 
 some definite ideas of the causes of these affections, 
 and consequently to a more uniform and scientific 
 mode of treating them. 
 
 I have endeavoured to shew that reproduction is 
 a phenomenon inseparable from morbific matter, 
 and that in all probability the vegetable kingdom is 
 the source of the germs. 
 
 * Feucbtersleben's Medical Psychology, p. 176, 177- 
 t Ibid. p. 321. 
 
192 
 
 The train of argument adopted is such as ap- 
 peared to me most natural for such an enquiry^ and 
 it rests now only with those who are capable of de- 
 ciding* whether such a course^ though (I am sensibly 
 aware) not without many faults in conception and 
 execution^ is calculated to advance the science of 
 medicine and the interests of mankind. 
 
 The real tree of knowledg'e_, possesses in the 
 spong-ioles of its roots^ an elective property^ by 
 which truth alone can enter ; nourished and sus- 
 tained by this^ it sends a fragrant incense and 
 breathing odour on high_, and dispels the mists 
 of ignorance and superstition. In natural causes 
 and reasonable deductions we must seek for instruc- 
 tion and solid information^ for in over-straining 
 either nature or art^ deformity and error must 
 inevitably be the result. 
 
 THE END. 
 
 NORMAN AND SKEEN, PRINTEnS, MAIDEN LANE, COVENT GARDEN. 
 
 /