LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Class BIOLOGY 
 
 LIBRARY 
 G 
 
WORKS BY T. MITCHELL PRUDDEN., M.D. 
 
 DIRECTOR OF THE PHYSIOLOGICAL AND PATHOLOGICAL LABORATORY 
 
 OF THE ALUMNI ASSOCIATION OF THE COLI-EGB OF 
 
 PHYSICIANS AND SURGEONS, NEW YORK 
 
 A Manual of Practical Normal Histology. i6mo, 
 cloth $i 25 
 
 u A handy book for students. Very practical and very intelligible." 
 The American Specialist, 
 
 41 We are happy to find that a really valuable addition has been made to 
 literature. The author is evidently a master of his craft, and 
 ft-lly understands the practical details. We are surprised at the amount 
 of information put in such small compass." Boston Medical and Surgicai 
 Journal. 
 
 The Story of the Bacteria. i6mo, cloth . 75 cents 
 
 " It is written in clear, concise sentences, without any effort at display, 
 and can be read with profit and enjoyed by any intelligent reader as welJ 
 as by the most scientific physician." Chicago Interocean. 
 
 Dust and Its Dangers. Uniform with " The Story of 
 the Bacteria." Illustrated .... 75 cents 
 
 " It is in one sense an alarmist book, but it alarms in a proper direction, 
 and performs a service that cannot be overvalued. . . . The 
 book is to be warmly commended, and should attract general attention." 
 Boston Gazette. 
 
 Drinking-Water and Ice Supplies, and Their Rela- 
 tions to Health and Disease. i6mo, cloth, illustrated, 
 
 75 cents. 
 
 ** Dr. Prudden's little book is crammed with information practical 
 information which to thousands of families would be worth, if duly 
 read and heeded, far more than money " Hartford Times. 
 
 G. P. PUTNAM'S SONS, PUBLISHERS, 
 
 NEW YORK AND LONDON. 
 
EXPLANATION OF THE PLATE. 
 
 FIG. I. A large mass of bacteria growing in a tube on a trans- 
 parent culture medium. This species is called Micrococcus luteus, 
 (page 40) and is a " pure culture " (page 35). 
 
 FIG. II. A gelatin plate culture (pages 36, 37, and 38), showing 
 several colonies of different species of bacteria growing in the thin 
 layer of solidified gelatin. Each colony is composed of thousands of 
 individual bacteria. (See Fig. v.) 
 
 The yellow colonies are those from which a small portion was 
 taken on the end of a sterilized needle and planted in the tube 
 shown after a few days growth in Fig. I. 
 
 The tube and plate in Figs I. and II. are represented of about one 
 third the natural size. 
 
 Fig. III. Several different forms of bacteria represented as they 
 look when stained with one of the anilin dyes and magnified about 
 i, CKDO times (see pages 15, 39, and 40). 
 
 Nos. i and 2 : Micrococci, single and in pairs. No. 3 : Micro- 
 cocci in chains, called streptococci. No. 4 : Tetrads of micrococci. 
 Nos. 5, 6, 7, and 8 : bacilli, showing different sizes and groupings 
 in No. 5, cilia are seen at the ends of some of the bacilli (page 16). 
 Nos. 9 and 10 : spiral bacteria ; those in No. 9 with cilia. Nos. 
 II and 12 : bacilli with spores (page 19). 
 
 FIG. IV. A cell in which are seen seven long slender bacilli 
 magnified about 3,000 times. 
 
 FIG. V. A single colony as seen under a low power of the 
 microscope on the plate culture, Fig. II. This is magnified about 
 20 times. 
 
THE 
 
 STORY OF THE BACTERIA 
 
 AND THEIR 
 
 RELATIONS TO HEALTH AND DISEASE 
 
 BY 
 
 T. MITCHELL PRUDDEN, M.D. 
 
 or THI 
 { UNIVERSITY J 
 
 NEW YORK & LONDON 
 
 G. P. PUTNAM'S SONS 
 
BIOLOGY 
 
 LIBRARY 
 
 6 
 
 / 
 
 COPYRIGHT BY 
 
 T. MITCHELL PRUDDEN 
 
 tEbc 
 
PREFACE. 
 
 THE Bacteria are so often nowadays the 
 subject of discussion and discourse ; so much 
 which is at once disquieting and untrue is said 
 about them, and they are withal of such prac- 
 tical importance to the health and well-being 
 of everybody, that it has seemed to the writer 
 worth while to bring together in some simple 
 fashion a little of our knowledge about them. 
 
 The aim then of this book is to present 
 some facts from a small corner of the domain 
 of Science in such form as will be plain to the 
 unscientific, and with these some extracts from 
 the lore of the physician which will, it is 
 hoped, be both interesting and useful to the 
 lay reader. 
 
 T. M. P. 
 
 iii 
 
 144339 
 
CONTENTS 
 
 CHAPTER PAGB 
 
 I. THE CELLS WHICH COMPOSE THE HUMAN BODY 
 
 WHAT THEY ARE, AND WHAT THEY Do . . i 
 
 II. WHAT THE BACTERIA ARE, AND SOME OF THE THINGS 
 
 WHICH THEY Do . . . . . . .14 
 
 III. How THE BACTERIA ARE STUDIED . . . .25 
 
 IV. SOME BACTERIAL CURIOSITIES . . . . .41 
 
 V. THE BACTERIA AS MAN'S INVISIBLE FOES . , .52 
 VI. THE BACTERIA OF SURGICAL DISEASES - . . .59 
 VII. THE BACTERIA WHICH CAUSE CONSUMPTION, OR 
 
 TUBERCULOSIS . . . .... . .70 
 
 VIII. BACTERIA AND TYPHOID FEVER 84 
 
 IX. THE RELATIONS OF BACTERIA TO ASIATIC CHOLERA . 90 
 X. THE RELATION OF BACTERIA TO DIPHTHERIA, PNEU- 
 MONIA, SCARLET-FEVER, ETC. . . . . .96 
 
 XI. IMPURE FOOD AND AIR AS SOURCES OF BACTERIAL 
 
 INFECTION ,..'.' . . . . . . 103 
 
 XII. IMPURE WATER AND ICE AS A SOURCE OF BACTERIAL 
 
 DISEASE 116 
 
 XIII. THE END OF THE STORY OF THE BACTERIA . . 134 
 INDEX I 3g 
 
or 
 
 VNIVER8ITY 
 
 THE STORY OF THE BACTERIA. 
 
 CHAPTER I. 
 
 THE CELLS WHICH COMPOSE THE HUMAN BODY 
 WHAT THEY ARE, AND WHAT THEY DO. 
 
 T3EFORE beginning to study those low- 
 U liest and smallest forms of life, the 
 bacteria, I wish to ask my reader to look with 
 me in this chapter at some of the higher and 
 more complex forms of living things. In do- 
 ing this we shall be following the course which 
 scientific research has taken, and from the 
 vantage-ground which we shall gain we shall 
 be able the more easily to spell out the simple 
 but significant story of the bacteria, which it is 
 the purpose of this little book to tell. 
 
 In general anatomy we learn that the body 
 consists of a bony framework, around which 
 
THE STORY OF THE BACTERIA. 
 
 various tissues and organs are securely and 
 compactly grouped. When we have learned 
 the size, shape, number, relations, and names 
 of all these parts, our study of macroscopic or 
 general anatomy is done. If, however, enter- 
 ing that department of anatomy known as 
 histology, or minute anatomy, we trace the 
 manner in which these parts are made beyond 
 the point where the naked eye can avail us, 
 we find that they are all composed of certain 
 tiny organisms called cells, and that these 
 cells are held together and associated by cer- 
 tain materials which lie between them. 
 
 Just as the chemist has his atoms and 
 molecules, to which in the last analysis he 
 refers the properties which all known sub- 
 stances possess, and explains by differences in 
 their nature and movements the various chemi- 
 cal phenomena which matter exhibits, so we 
 may refer both the structural features and all 
 the activities of the animal body back to the 
 structure and activities of our elements the 
 cells. While the chemist, however, must infer 
 the existence of his atoms from their deeds, 
 armed with the microscope we can see our 
 
THE STORY OF THE BACTERIA. 3 
 
 cells, observe the things they do, and definitely 
 trace out their life-history. 
 
 Cells are little masses of matter of peculiar 
 chemical constitution, and of varied shape and 
 consistence, which at some time exhibit that 
 complex of phenomena which we call life : and 
 the life of one of the higher animals is simply 
 the sum of the more or less independent but 
 co-ordinated lives of the cells which compose 
 it, all acting in harmony. 
 
 Living things differ from the non-living in 
 that they have certain activities through which 
 their life is expressed. In the first place, they 
 are capable, in spite of various opposing forces, 
 of maintaining their individuality, and by 
 holding a balance between waste on the one 
 hand and assimilation on the other, a series of 
 capacities arise which we call nutrition, growth, 
 and development. Living things, in the sec- 
 ond place, possess certain activities by means 
 of which they are capable of producing new 
 individuals like themselves in other words, 
 they are endowed with the power of reproduc- 
 tion. Lastly, living bodies, in response to 
 varied influences, are capable of doing certain 
 
THE STORY OF THE BACTERIA. 
 
 things in the way of movements or of elabora- 
 tion of peculiar chemical products, etc., and 
 these are called their functions. 
 
 It will be observed that in enumerating 
 these activities I have spoken of them not as 
 characteristic of man, or of any special animal 
 or plant, but of living things in general. All 
 life finds expression in these ways. The means 
 by which the living being does these things 
 may be in one case exceedingly primitive, and 
 in another very complicated, but this does not 
 alter the essential character of the ends which 
 it achieves. 
 
 If you tie a bit of muslin over a water faucet 
 and allow the water to trickle slowly through 
 it for a few hours, you will find on removing 
 it that a more or less abundant greenish scum 
 has collected on the cloth. Wash this care- 
 fully into an open dish, and let it remain for a 
 few days in a light warm place, and then 
 examine the sediment under a microscope, 
 and you will find a very celebrated creature. 
 It is called an amoeba. It looks like a little 
 lump of transparent or slightly granular jelly. 
 You will see it thrusting out portions of itself 
 
THE STORY OF THE BACTERIA. 5 
 
 in the form of longer or shorter arms, and 
 then withdrawing them and sending out 
 others in another place, apparently in the 
 most aimless way ; or you may see it rolling 
 itself over and over, or, if I may so say, flow- 
 ing along so that it travels with considerable 
 speed. Perhaps some microscopic vegetable 
 may lie in its way, and it will flow over and 
 enclose this, and, after digesting portions of it, 
 expel the residue from whichever side or sur- 
 face of its body may be most convenient. If, 
 in a quiescent condition, it be touched by an 
 external object, you may see it move in direct 
 response to the irritation. If you are fortu- 
 nate in your observation, you may see a con- 
 striction appear around some part of the lump, 
 which grows gradually deeper until a portion 
 of the mass separates from the rest and crawls 
 off on its own hook as a new and independent 
 amoeba. It has no lungs and yet it breathes ; 
 no mouth, still eats ; no definite shape, yet 
 grows ; no nerves, yet is sensitive ; no sex, 
 yet may give birth to endless progeny. 
 
 Now this amoeba is one of the lowest and 
 simplest of creatures, and is the type of a 
 
THE STORY OF THE BACTERIA. 
 
 cell a creature which is composed of a single 
 cell and all the activities which I have men- 
 tioned as characteristic of living things are 
 exhibited in it. It is a perfectly independent 
 being, doing every thing for itself, and doing 
 nothing particularly well, except, perhaps, 
 performing the function of reproduction, 
 which it does with such ease and nonchalance 
 as leaves little to be desired. The young 
 which it produces are just like the parent, 
 single cells, and their very first post-natal act 
 may be to give birth to other amcebas. 
 
 Now let us advance a step in the scale of 
 being, to an animal composed of several cells. 
 There is a little creature, one of the group of 
 sponges, called olynthus. Let us start with 
 the ovum of the animal, which is a single cell, 
 not very unlike the amceba in appearance. 
 Under suitable conditions, this cell divides as 
 the amoeba does, and two cells are produced, 
 just exactly alike. They do not separate, 
 however, as do the amcebas, to become inde- 
 pendent individuals, but remain fastened 
 together ; then each cell divides again, and 
 these still further, until we have a little mass 
 
THE STORY OF THE BACTERIA. J 
 
 of cells all looking alike, and the whole some- 
 what resembling a mulberry in shape. But 
 now a change comes ; the cells on the outside 
 become longer than the rest, and little hair- 
 like processes, called cilia, grow out from them 
 and begin to vibrate to and fro, and, acting 
 like tiny oars, propel the little creature through 
 the sea. Presently the rest of the cells arrange 
 themselves so as to form a central cavity, with 
 an opening at one side, the whole looking like 
 a tiny cup. The animal now attaches itself to 
 a sea-weed or a rock, and no longer needing 
 the locomotive cilia, they disappear ; but as it 
 can no longer travel, it can no longer seek its 
 food, which must be brought to it. Accordingly, 
 we presently find that through the sides of its 
 body little holes appear, and the cells lining 
 the central cavity lengthen and develop cilia, 
 whose vibrations maintain a current of water 
 through the body, which brings with it oxygen 
 and food. This is the adult olynthus. 
 
 Now observe, if you please, what has hap- 
 pened in the development of this little creature. 
 A single cell divided into several cells, at first 
 all just alike, and all doing the same thing. 
 
8 THE STORY OF THE BACTERIA. 
 
 But soon, as if in response to the growing 
 needs of the animal, certain of the cells devel- 
 oped a special apparatus, and a special capacity 
 for performing rapid movements, and this ca- 
 pacity was associated with changes in the form 
 of the cells, a specialization which signalized 
 its advance to a higher type of existence. 
 
 Just here we come upon the great principle, 
 in a very simple form, upon which the enor- 
 mous differences between higher and lower 
 animals rest, the principle of the physiological 
 division of labor in cells. The more perfect 
 the individual is, the more elaborate do we 
 find the expression of this principle. 
 
 The difference between the amceba and the 
 olynthus from our present point of view that 
 which makes of the latter a higher animal than 
 the former is that it has a certain group of 
 cells set apart to do a special thing, to move 
 rapidly ; Amceba moves, but not so rapidly 
 nor with such directness. If another group of 
 cells were set apart in olynthus to do the 
 digesting, no new cell powers would be devel- 
 oped which the amceba does not possess, the 
 primitive assimilating power would simply be 
 

 { UNIVERSITY j 
 
 THE STORY OF THE 9i&Q&&W\**S 9 
 
 specialized and intensified, and the animal 
 would have risen to a higher grade of being. 
 
 It would not be difficult, did time permit, to 
 trace the manner in which, as we pass upward 
 in the animal series, certain groups of cells be- 
 come more and more elaborate in structure as 
 they assume higher and more specialized ca- 
 pacities. We cannot tarry for this, but will 
 glance for a moment at the exhibition of this 
 principle in the development of man. In man, 
 too, life commences in a single cell called the 
 ovum ; a cell which, though harboring poten- 
 tialities of the highest order, in many respects 
 greatly resembles our little denizens of the 
 water. This cell, under suitable conditions, 
 divides and subdivides, forming a little cluster 
 of cells all looking alike. Then these cells 
 arrange themselves in layers ; some of them 
 assume special forms as they increase in num- 
 ber, and develop special capacities, and group 
 themselves to form the various tissues and 
 organs of the mature body, which finally is 
 formed of a grand community of co-ordinated 
 groups of cells, some of which have acquired 
 the power to do special things in the most 
 
10 THE STORY OF THE BACTERIA. 
 
 perfect way, while others have remained in a 
 condition of comparatively low organization. 
 
 Let us look at two examples of these two 
 types of cells from the adult body first at 
 certain muscle cells. These in the very young 
 animal look just like many other cells ; they 
 are individuals, they are alive and their life 
 finds expression, just as the amoeba's does, in 
 certain activities nutrition, growth, function, 
 and reproduction. Presently they become 
 longer than their neighbors, little striations 
 appear along their sides, they grow long and 
 narrow until at last they are little thread-like 
 bodies with a very complicated internal struct- 
 ure, anJ are grouped in bundles to form the 
 muscles as we see them with the naked eye. 
 The peculiarities of structure of these muscle 
 fibres are necessary for the performance of the 
 work which they have specially to do namely, 
 the accomplishment of rapid and powerful 
 movements. Now the capacity of the muscle 
 cells for doing this work has been acquired, if 
 I may say so, at the expense of some of the 
 other capacities which they originally possessed 
 in common with other cells. Thus the power 
 
THE STORY OF THE BACTERIA. II 
 
 of reproduction is in them almost if not quite 
 completely absent. They can also no longer 
 seek out and take up crude food, but it has to 
 be prepared for and brought to them, and in 
 order that this may be done certain other cells 
 in the body develop the power of elaborat- 
 ing a peculiar fluid gastric juice, which helps 
 to change the crude food so that it finally 
 becomes fitted for the nourishment, among 
 others, of the special workers, the muscle 
 cells ; other cells the red blood cells de- 
 velop the capacity of bringing them oxygen, 
 and in doing so have lost many capacities 
 which are possessed by lower forms. Other 
 cells develop in a peculiar way to form the 
 nerves by which all the various parts of the 
 body are brought into harmonious action, and 
 so on Thus we see in the higher animals 
 each highly developed cell working for the 
 others as well as for itself and for the organ- 
 ism as a whole, only its chief endeavor is con- 
 centrated in some one special thing, and as a 
 result of this concentration some of the more 
 general cell powers are lost or diminished. 
 Did time permit, I should like to picture for 
 
12 THE STORY OF THE BACTERIA. 
 
 you the character and destiny of some of the 
 lower forms of cells, which we find in the hu- 
 man body, those which have not undergone 
 that differentiation in structure and function 
 which belongs to higher types ; to speak of 
 the marvellous potentialities which are dor- 
 mant in them ; to show you how their very 
 simplicity of existence, the absence of special 
 powers, and their boundless capacity for re- 
 production particularly fit them to become the 
 conservators of the individual ; to indicate 
 what an important role some of them play 
 in the healing of wounds and in the formation 
 
 o 
 
 of new tissues. So we are not to think of the 
 lower forms of cells in the body as insignifi- 
 cant, because under ordinary circumstances 
 their being and performances are humble 
 and inconspicuous, for they seem to be ever 
 ready, either resting quietly in their tiny nooks 
 within the solid tissues, or driven restlessly in 
 the rushing torrent of the blood, to assume 
 again the lowly but active powers of embry- 
 onic cells, and begin when necessary the work 
 of reproduction and repair. 
 
 These cells have, too, a most important role. 
 
THE STORY OF THE BACTERIA. 13 
 
 as we shall see by and by, in combating the 
 incursion of certain forms of bacteria which 
 now and then obtrude themselves into this 
 happy family of cells which makes up the 
 human body. 
 
 We have thus seen that all the varied struct- 
 ures and functions of the human body are but 
 the combined expression of the structure and 
 lives of the cells which compose it, all co-ordi- 
 nated and working in harmony by means of 
 self-built, cellular mechanism ; that, starting 
 with the type of the most simple of living 
 things, a single cell, the finished organism is 
 an aggregate of the progeny of the original 
 cell, some groups of which have developed 
 special forms and powers, in accordance with 
 a universal principle in nature ; that the doc- 
 trine of evolution, even should the record of 
 the rocks be incomplete and perfect continuity 
 in the grouping of living species fail, still finds 
 epitomized in every animal and plant which 
 has escaped from the primitive simplicity of 
 the lowest forms, a most pertinent illustration 
 and convincing proof. 
 
CHAPTER II. 
 
 WHAT THE BACTERIA ARE, AND SOME OF THE 
 THINGS WHICH THEY DO. 
 
 " I "HERE are many very good reasons for 
 A believing that when life first appeared 
 upon the earth it showed itself in a very sim- 
 ple and primitive form, in some such form 
 perhaps as we have seen in the amoeba or 
 other simple cells. But as the ages passed, in 
 accordance with the principles of the physio- 
 logical division of labor, which we have glanced 
 at in the last chapter, many of the living 
 beings gradually assumed more and more 
 complex forms and capacities. 
 
 Not all living things, however, shared in 
 these evolutionary changes. There is, in fact, 
 a great group of lowly plants, so small as to 
 be quite invisible to the naked eye, and which 
 until within a few years have been entirely 
 unknown to man, which still linger in the 
 
 14 
 
THE STORY OF THE BACTERIA. 15 
 
 primitive simplicity which we imagine to have 
 belonged to the earth's earliest denizens. 
 These are the bacteria. 
 
 So small are the bacteria, and so simple in 
 their structure and activities, that it has not 
 been an easy task for scientific men to decide 
 whether they belonged among animals or 
 plants. It is now definitely settled, however, 
 that they are plants, and are closely related 
 to the algae. 
 
 The bacteria vary a good deal in shape, but 
 in general they are either spheroidal or ovoidal, 
 like a billiard-ball or an egg ; or rod-shaped, 
 like a lead-pencil ; or spiral-shaped, like a cork- 
 screw. 
 
 They are in general so very small that we 
 can hardly form a conception of them except 
 by comparison with some well known objects. 
 One of the most common of the bacteria is a 
 little rod, so small that if you were to put fif- 
 teen hundred of them end to end, the line 
 would scarcely reach across the head of an 
 ordinary pin. If you look at them with a 
 magnifying power so great that, if it could be 
 applied to him, it would make a man look 
 
1 6 THE STORY OF THE BACTERIA. 
 
 about four times as big as Mount Washington, 
 they do not look larger than this. We can 
 make out, however that they are made up of a 
 slightly granular material surrounded by a 
 somewhat denser envelope. 
 
 The bacteria appear under the microscope 
 as pale translucent bodies, and the student 
 usually finds it necessary, in order to see their 
 outlines distinctly, to stain them with some 
 one of the aniline dyes red, or blue, or violet, 
 when they become very distinct. 
 
 When they are alive and suspended in fluids 
 many of the rod-like and spiral bacteria can 
 perform the most elaborate and astonishing 
 series of movements. They swim slowly, they 
 turn about, they roll over, they wriggle, dart 
 forward, retreat, bang against one another, 
 rest awhile, sway to and fro, plunge off again, 
 and so on through varying phases of move- 
 ment until the head swims and the eye tires in 
 following them. This movement, in some of 
 the bacteria at least, is induced by a little hair- 
 like projection from the end of the organism, 
 which vibrates rapidly to and fro. It is very 
 difficult to see these little projections or cilia, 
 
THE STORY OF THE BACTERIA. I/ 
 
 even with the most powerful microscopes, but 
 notwithstanding this, they have actually been 
 photographed, and in some cases the image 
 of the cilia, which failed to make an impres- 
 sion on the retina, has been caught and made 
 permanent by the sensitive plate in the camera. 
 
 Warmth, moisture, oxygen, and a certain 
 amount of organic matter are the simple con- 
 ditions which are required for their activities. 
 
 When the conditions are favorable they may 
 increase in number to a degree which is limited 
 only by their surroundings. A little constric- 
 tion appears around one of the bacteria ; it 
 grows a little longer, a partition forms across 
 the middle, and in the place of one there are 
 two full-fledged bacteria. These may at once 
 fall apart and each new individual go on di- 
 viding as before, or they may cling together, 
 forming threads or chains of varying length, 
 or clumps or masses. 
 
 So rapid is this process of reproduction that 
 a single germ by this process of growth and 
 subdivision may give rise to more than sixteen 
 and a half millions of similar organisms within 
 twenty-four hours. It has been calculated by 
 
1 8 THE STORY OF THE BACTERIA. 
 
 an eminent biologist that, if the proper condi- 
 tions could be maintained, a little rod-like 
 bacterium, which would measure only about a 
 thousandth of an inch in length, multiplying 
 in this way, would in less than five days make 
 a mass which would completely fill as much 
 space as is occupied by all the oceans on the 
 earth's surface, supposing them to have an 
 average depth of one mile. 
 
 Let not the timid soul tremble, however, for 
 the principles of the survival of the fittest and 
 the influences of environment have kept our 
 prolific organisms so well in check that the 
 world had grown very old and its favored 
 nursling, man, pretty well along in experience 
 and skill before ever he recognized the exist- 
 ence of these his microscopic contemporaries 
 and possible ancestors. 
 
 The struggle for existence goes on where 
 varying forms of bacteria are growing' as fierce- 
 ly as ever it did among more highly organized 
 beings. One race succeeds another, one spe- 
 cies adapts itself to the conditions which 
 brought about the extinction of its predeces- 
 sors. Hardy individuals struggle with their 
 
THE STORY OF THE BACTERIA. 
 
 weaker neighbors as the food grows scanty in 
 their microscopic seas, and the weaker goes to 
 the wall. 
 
 Many forms possess the power of living and 
 multiplying in the manner described above so 
 long as the proper conditions prevail, but when 
 life, owing to some change in the environment 
 becomes no longer possible, the vital powers 
 collect themselves in a little shining mass in 
 one end of the bacterium, which surrounds 
 itself by a dense membrane, and in this form, 
 which is called a spore, the individual can sur- 
 vive adverse conditions which in the ordinary 
 form would have destroyed its life. Restore 
 it to the needed conditions and the spore 
 swells into a bacterium again, and the roots of 
 a new ancestral tree begin to sprout. 
 
 These bacteria are really very simple forms 
 of cells, and like the cells which we have looked 
 at in the last chapter, their life expresses itself 
 in certain activities ; they move, they nourish 
 themselves and grow, they reproduce their 
 kind. They have the power in carrying on 
 the processes of their own nutrition, when 
 moisture and air are present, of tearing to 
 
20 THE STORY OF THE BACTERIA. 
 
 pieces, in the chemical sense, dead organic 
 material, using up such parts of it as they need 
 for their own purposes, and setting free the 
 rest in such form as to be available for the use 
 of other living things. 
 
 Everybody knows who thinks about it, that 
 the supply of such material as makes up the 
 bulk of the tissues of man, animals, and plants, 
 on this earth, is limited. So that if things were 
 not so arranged that living beings should have 
 the use of the material which goes to make up 
 their bodies for only a comparatively short 
 time, the supply would run short and new be- 
 ings could not continue to appear. 
 
 When that mysterious group of activities 
 which we call life ceases to be manifested, in 
 animals and plants alike, if moisture and oxy- 
 gen and sufficient warmth are present, that 
 process which we know as putrefaction or de- 
 cay begins, by which the old combinations of 
 matter are broken up and the material set free 
 for the use of other beings. Now just here 
 enter the bacteria. It is they who tear these 
 old organic compounds asunder, use a little of 
 them as may suit their own needs, and turn 
 
THE STORY OF THE BACTERIA. 21 
 
 over the rest to their earth neighbors, who 
 have got higher up the scale of being, but not 
 yet so far as not to need absolutely and hourly 
 oxygen, hydrogen, nitrogen, and carbon, to 
 keep their life's furnaces a-going. 
 
 Milk is a most excellent food for many forms 
 of bacteria, and among those which are com- 
 monly present in milk is one which causes it to 
 become sour when left to itself. Other forms 
 of bacteria develop those peculiar chemical 
 compounds which give to cheese its special 
 and varying flavors. It is, in fact, a very motley 
 group of chemical substances which these bac- 
 teria set free in feeding themselves on nature's 
 waste organic materials. Sometimes they are 
 very bad smelling gases, sometimes aromatic 
 substances, sometimes they are sweet, some- 
 times they are sour. But sooner or later they 
 are used by some animal or plant, and so again 
 enter the domain of life. Thus ever in cease- 
 less alternations between life and death these 
 elemental combinations come and go. And 
 ever since life emerged from its primal simple 
 forms on the earth, the bacteria have silently 
 gone on tearing the worn-out and useless to 
 
22 THE STORY OF THE BACTERIA. 
 
 pieces and turning it over in new combination 
 to other forms of life. 
 
 It was formerly believed that such lowly 
 organisms as the bacteria could spring at once 
 into being wherever in nature the conditions 
 were favorable, but this notion of spontaneous 
 generation has long since been given up, be- 
 cause it was shown to have depended upon in- 
 sufficient and crude observation. We now be- 
 lieve that every living thing comes from some 
 pre-existing living thing, be it man, beast, 
 plant, or cell, and this principle holds true as 
 well among the bacteria as among more highly 
 organized beings. 
 
 There is an enormous number of different 
 species of bacteria, each one of which appears 
 to preserve its individual characters under all 
 the varying conditions and vicissitudes to which 
 it is subject. They are to be found every- 
 where in nature. Where putrefaction and de- 
 cay are going on they are most abundant, but 
 where any form of life can exist they are pres- 
 ent, either dry and inactive, or where moisture 
 and food are present, growing and multiplying 
 in such degree as their surroundings will per- 
 
THE STORY OF THE BACTERIA. 23 
 
 mit. In all natural surface waters, in the soil, 
 on all fruits, vegetables, and plants, in the 
 mouths and digestive canals of men and ani- 
 mals, on the skin, wherever dust can go or 
 collect, there are bacteria of various forms in 
 greater or smaller numbers. 
 
 So common and abundant are the bacteria 
 that we are constantly taking enormous num- 
 bers of them into the system with all of our 
 uncooked food. We should not, however, 
 think of these little organisms which we thus 
 unwittingly consume as things necessarily un- 
 clean or unwholesome, for they are only little 
 cells after all, and nearly all the food which we 
 consume, whether animal or vegetable, is made 
 up of masses of cells which are either fit to eat 
 in their natural condition, as in the pulp of 
 fruits, or become so by simple cooking or other 
 manipulation. 
 
 There is really very little difference so far as 
 wholesomeness is concerned between, the few 
 thousand vegetable cells which we call bacte- 
 ria which may be clinging to the surface of a 
 grape, and a few hundred vegetable cells of 
 larger size of which the grape itself is com- 
 
24 THE STORY OF THE BACTERIA. 
 
 posed. Both are alike worked over by the 
 digestive organs, under ordinary conditions, 
 into nutritive material for the uses of the 
 body. 
 
 There are poisonous vegetables, and there 
 are, more 's the pity, as we shall see by and 
 by, poisonous bacteria, but we do not shudder 
 as we swallow a mushroom to think what 
 might have happened to us if we had swal- 
 lowed a poisonous toadstool instead ; we sim- 
 ply trust to the gardener, or if he is dishonest 
 or ignorant, see to it ourselves that the poison- 
 ous are not liable to get in with the other 
 plants, and then go on enjoying our delicacies 
 like sensible people. 
 
 It will thus be seen that the role of the 
 bacteria in nature, though humble and silent, 
 is an exceedingly important one. They are 
 indispensable to the continuance of the higher 
 forms of life upon the earth. They may well 
 be called man's invisible friends. 
 
CHAPTER III. 
 
 HOW THE BACTERIA ARE STUDIED. 
 
 IF you take a small whisp of hay, put it in 
 an open jar, and covering it with water, 
 set it in a warm place for a day or two, you 
 will presently see that the water which was at 
 first perfectly clear, begins to get turbid, and, 
 after a while, a grayish scum collects on the 
 top. Now the water begins to give off a dis- 
 agreeable odor of decay. This is what has 
 happened. The bacteria of various forms 
 which, in the dried condition were clinging to 
 the hay, or which were in the water, have mul- 
 tiplied to such an extent that they made the 
 water turbid, and many of the mobile forms 
 have sought the surface, where the oxygen 
 was most abundant. The solution of organic 
 material from the hay has furnished an 
 abundance of food, and as the bacteria 
 have torn this into simpler forms to get the 
 
 25 
 
26 THE STORY OF THE BACTERIA. 
 
 particular elements which they needed for 
 their own use, the freed material, in part in 
 the form of bad-smelling gases, has either been 
 set free into the air or remains absorbed in the 
 water. 
 
 If you examine a tiny droplet of the water 
 from time to time with the microscope, you 
 will find that it is swarming with various forms 
 of bacteria, rods, balls, and perhaps spirals, 
 many of them in active motion. But you will 
 notice that from day to day the prevailing 
 forms change. One day the little rods will be 
 most abundant, the next these may have 
 largely disappeared, and perhaps the little 
 balls are the most common forms. Then 
 perhaps a new set of rods or balls will appear 
 of a different size from the first. After a 
 while you will find that the bottom of the jar 
 has become covered with a light-colored sedi- 
 ment, and the water has become clearer. 
 
 The bacteria of one form or another have 
 gone on dividing and subdividing, breaking up 
 the dissolved organic matter in the water until 
 either they had used up the special form of 
 material which was best suited to their needs, 
 
THE STORY OF THE BACTERIA. 
 
 or until the material which they had set free 
 had so far accumulated as to prevent their fur- 
 ther growth, and then they died, self-poisoned, 
 just as a man might who should be shut up in 
 a tight room until the accumulation of the 
 products of his respiration and excretion had 
 made further life impossible. Or they may 
 die because other species of bacteria growing 
 in the same fluid furnish material which poi- 
 sons their neighbors. So the procession of 
 life goes on, until the bottom of the jar be- 
 comes a veritable graveyard of races. 
 
 Some forms of the bacteria, however, which 
 seem dead, and fall with the rest to the bot- 
 tom of the jar, are really only in a resting 
 stage ; they have formed spores within them- 
 selves in the manner described above, and may 
 lie dormant until the proper conditions come 
 again, when they may spring into renewed 
 activities. But new species may from time to 
 time fall into the jar from the air and find in 
 the water, which was rank poison for the dead 
 species at the bottom, just the food they need, 
 and so will the drama of life and death be 
 enacted anew for long periods. 
 
28 THE STORY OF THE BACTERIA. 
 
 In such a confusing mixture as this the stu- 
 dent finds it no easy task to make out much 
 except differences in form and movement, 
 in the jumble of tiny plants. What he needs 
 to do is to get each species by itself, so that 
 he can cultivate it alone, and find out what it 
 is and does under more simple conditions. 
 
 The device which was formerly in vogue, 
 and which was called the fractional method of 
 separation, was to make some beef-tea which 
 is pretty good food for most bacteria, and 
 putting a little of this in a great many separate 
 little tubes, carefully heat them so as to kill all 
 the bacteria which might by chance have been 
 in the flasks or in the materials from which the 
 beef-tea was made. The investigator also 
 takes a large flask of water and kills by heat- 
 ing all the bacteria which it may contain. Now 
 he dips the end of a fine needle, which has 
 just been heated red-hot to kill the omnipres- 
 ent germs, into the putrefying mixture. He 
 rinses off the invisible amount of material 
 which clung to the needle into the pure water 
 in the large flask, and thoroughly shakes it so 
 that the bacteria which he has put into it may 
 become equally distributed through it. 
 
THE STORY OF THE BACTERIA. 2Q 
 
 He calculates that the bacteria which he has 
 thus put into the large flask of water will have 
 been so much diluted and separated that, if he 
 now dips a needle into this water, or takes out 
 a small drop, and rinses it off into one of the 
 tubes of beef-tea, and does this for each one 
 of the several beef-tea tubes which he has pre- 
 pared, into some of them he will have intro- 
 duced, small as they are, only one single indi- 
 vidual bacterium. 
 
 He now sets his beef-tea tubes away in a 
 warm place where no accidental contamination 
 can occur, and lets them stand until the fluid 
 begins to get turbid. Now, by a careful mi- 
 croscopical examination he can tell whether 
 one or several forms of bacteria are growing 
 in his tubes, and if in any of them only one 
 form is present he has succeeded, and has what 
 he calls a culture of some particular bacterial 
 species. This he can study at his leisure, plant 
 and replant it in fresh beef-tea tubes, and find 
 out to a certain extent what its habits are, what 
 new chemical substances it produces as it feeds 
 itself from the beef-tea, etc. 
 
 But this is a long and wearisome process 
 and somewhat uncertain^ in its results too, 
 
3O THE STORY OF THE BACTERIA. 
 
 because one can never be quite certain from a 
 microscopical examination of small portions of 
 a beef-tea culture, but that in some other part, 
 for he cannot examine it all, other forms of 
 bacteria may be present. 
 
 Nowadays, although we find beef-tea very 
 useful on many occasions in cultivating the 
 bacteria, we most frequently make use of solid 
 foods. 
 
 Boiled potatoes, which have been carefully 
 cleansed and sterilized that is, free from any 
 bacteria from the soil or air by steaming, are 
 usually first prepared. These are cut in halves, 
 with knives sterilized by heat, being held in 
 the fingers which have been freed from living 
 germs by washing with corrosive sublimate, 
 and placed under sterilized bell-jars or in tubes, 
 so that they may not be contaminated by the 
 accidental falling upon them of bacteria from 
 the air. Now, by means of a platinum wire 
 set in a glass handle, which has been sterilized 
 by heating to redness, a tiny bit of the bacteria- 
 containing material is conveyed to the cut 
 surface of the potato, and the latter is covered 
 again and set away for a day or two in a warm 
 
THE STORY OF THE BACTERIA. 31 
 
 place. Usually at the end of this time, if all 
 goes well, there will be a growth of the bac- 
 teria on the potato so large as to be quite 
 visible to the naked eye. This growth, or 
 "colony," as it is called, which is made up of 
 myriads of individual bacteria, the offspring 
 of those planted, in many cases presents very 
 characteristic ways of growing or special 
 colors, etc., characters often by which particu- 
 lar species of bacteria may be distinguished 
 from all others, even without the aid of the 
 microscope. This gross appearance of the 
 growing colonies is useful in the recognition 
 of species which under the microscope look 
 very much alike. Just as in agriculture, if 
 one were in doubt as to two specimens of seed 
 which closely resembled one another say tur- 
 nip and rape, for example by sowing them in 
 the ground and observing the resulting plants, 
 all doubt would be removed. 
 
 In thus planting the invisible and minute 
 bacteria, and allowing them to grow until such 
 large masses of colonies are formed that we 
 can readily see and study them with the naked 
 eye, we are realizing in another field a project 
 
32 THE STORY OF THE BACTERIA. 
 
 which was urged with a good deal of persist- 
 ency some years ago for finding out if there 
 were inhabitants in the moon, and for com- 
 municating with them. 
 
 It was proposed to build in outline on some 
 great plain on the earth's surface, like that of 
 Siberia, a gigantic structure so large that even 
 assuming that the lunar inhabitants had no 
 telescopes, it would be visible to them. This 
 structure was to have some simple suggestive 
 mathematical form like a circle or triangle. 
 Seeing such a thing appear on the earth's sur- 
 face, it was thought that the lunar inhabitants 
 would probably " catch on " this phrase was 
 not known in those primitive times and erect 
 a similar structure, and thus communication 
 would be established. The moon project fell 
 through, but as we have seen by a somewhat 
 similar device, we actually make the inhabit- 
 ants of an unseen world communicate to us 
 to-day some of the secrets of their hidden life. 
 
 But the knowledge derived from the mode 
 of growth of bacteria on potatoes is limited, 
 because as the potato is opaque we can see 
 only the surface of the colony ; and, further- 
 
THE STORY OF THE BACTERIA. 33 
 
 more, not all the bacteria grow well on pota- 
 toes, and some do not grow upon them at all. 
 So the next step is to make some transparent 
 solid substance which shall be a suitable soil for 
 bacterial growth. One of the most common and 
 useful substances for this end is a 10 per cent, 
 solution of gelatin which is mixed with beef- 
 tea, pepton, and a little common salt, and then 
 made neutral or slightly alkaline by carbonate 
 of soda. This mixture, carefully heated so as 
 to destroy all bacteria which might be present 
 in its ingredients, is filled into ordinary glass 
 test-tubes which have been sterilized by a high 
 temperature. These are filled about one third 
 full of the gelatin mixture, and the opening 
 is stopped by a plug of cotton batting. Through 
 a long plug of cotton, bacteria cannot pass ; 
 the air can enter and leave the tube, but all 
 bacteria are caught by the fibres of the cotton. 
 After the gelatin has become cool and solid, 
 by means of a sterilized platinum wire, some 
 of the bacteria are introduced into the gelatin, 
 the cotton plug being removed for an instant 
 for this purpose. Being transparent, the gela- 
 tin permits us to see from the sides as well as 
 
34 THE STORY OF THE BACTERIA. 
 
 from the surface the exact mode of growth of 
 the particular form of bacteria introduced into 
 the tube, and thus we learn a new set of char- 
 acteristics for the different species. 
 
 But if we need to keep our bacteria at a 
 higher temperature than that of an ordinary 
 room, say at the temperature of the body, at 
 which alone some forms will grow, the gelatin 
 would melt and the bacteria would be scat- 
 tered through it, and the characteristic mode 
 of growth of the masses or colonies would be 
 lost. So, for this purpose we use, instead of 
 gelatin, Agar-Agar, a material derived from a 
 sea-weed, which in one per cent, solution forms 
 a gelatinous solid transparent mass, which 
 may be heated to above the temperature of 
 the body without fluidifying. To this are 
 added, as to the gelatin, beef-tea, pepton, etc. 
 
 By the use of these various soils, or "cult- 
 ure-media," as they are called, we can arrive 
 at a series of characteristics in the mode of 
 growth of various bacteria by which, together 
 with their form when seen under the micro- 
 scope, we can distinguish them one from the 
 other, just as the naturalist distinguishes from 
 each other nearly related animals and plants. 
 
THE STORY OF THE BACTERIA. 35 
 
 It is obviously of the greatest importance, 
 as we have seen above, that we should be able 
 to separate different species of bacteria from 
 one another in the living condition, so that we 
 may have growths or colonies which shall con- 
 tain one species alone without admixture with 
 any other. These are called " pure cultures." 
 This is by no means an easy task, as will be 
 appreciated when we consider how exceedingly 
 minute the organisms are, and how much dan- 
 ger there is that the bacteria floating every- 
 where invisibly in the air, may become mixed 
 with those forms which we are studying. By 
 a very simple device elaborated by Dr. Koch, 
 of Berlin, we are, nevertheless, able at any 
 time to separate one species from another with 
 the utmost certainty, or from a mixture of 
 many species to get into separate tubes pure 
 cultures of each species by itself. This is 
 accomplished by what is called the "plate 
 culture," the details of which are as follows : 
 Suppose we have a mixture, say a sample of 
 impure drinking water, which contains 
 four different species of bacteria, which we 
 wish to get into pure cultures in separate 
 tubes. 
 
36 THE STORY OF THE BACTERIA. 
 
 We mix thoroughly a small amount of the 
 bacteria-containing water with a much larger 
 amount of the above-described nutrient gela- 
 tin, rendered just fluid by heat. Then we 
 pour this mixture out onto a glass plate which 
 has been carefully sterilized by heat, so as to 
 form a thin layer, which soon cools and be- 
 comes solid. The glass plate is now covered 
 with a bell-jar to prevent the access to it of any 
 bacteria which may be floating in the air, and 
 to prevent its drying, and set it away at the 
 proper temperature. The individual bacteria 
 which were scattered through the gelatin layer 
 will presently commence to grow. 
 
 After a few hours or days, as the case may 
 be, if we look at the gelatin-film we see, some- 
 times with the naked eye, sometimes only un- 
 der the microscope, little points or masses 
 scattered through the gelatin, which are colo- 
 nies of bacteria, each one consisting of hun- 
 dreds or thousands of the organisms which 
 have grown from the single organism which 
 was fixed at that point as by a solid wall when 
 the gelatin cooled. 
 
 Of course, it sometimes happens that two or 
 
THE STORY OF THE BACTERIA. 37 
 
 more of the original germs either of the same 
 or different species were solidified in the gela- 
 tin when it cooled at the same place, and then 
 the resulting colony will consist of all the 
 organisms which have grown at this point, 
 mixed together or growing closely side by 
 side. In most cases, however, the little colo- 
 nies are composed of the descendants of a 
 single germ, and if we put the gelatin plate 
 under the microscope we can see the different 
 forms of the colonies which have grown from 
 the different species. The differences in the 
 mode of growth of the bacteria when planted 
 and studied in this way are manifold ; some 
 are colored, red, green, yellow, orange, violet, 
 brown, etc. ; some are colorless, some have 
 sharply defined smooth edges, some are jagged 
 or fringed, some are beaded, or send out little 
 spines ; some cause the gelatin in their imme- 
 diate vicinity to liquefy, so that they come to 
 lie in a little pool of fluid in a pit or depression 
 in the solid gelatin. 
 
 Now, by examining the plate microscopically 
 we cannot only see how many different forms 
 of colonies there are and each different form 
 
38 THE STORY OF THE BACTERIA. 
 
 of colony indicates a difference in the species 
 of bacteria composing it, but nothing is 
 simpler than, directly under the microscope, to 
 take out on the tip of a sterilized platinum 
 wire little bits from each one of the different 
 forms of colonies, and transfer them to separate 
 tubes of gelatin. Thus we secure "pure cult- 
 ures " of all the different forms of bacteria 
 which were contained in the original mixture. 
 Thus, minute as the individual bacteria are, 
 lying far below the power of unaided vision, 
 we are able to manipulate them with as much 
 certainty as the agriculturist does his larger 
 plants. 
 
 When we have thus got different species of 
 bacteria separated from one another in the 
 form of pure cultures we can experiment on 
 them in many ways, and learn their varying 
 characteristics. We can plant them under 
 such conditions that their oxygen supply is 
 limited, and learn whether they do or do not 
 thrive ; we can see whether they grow best at 
 high or low temperatures, and what degrees 
 of heat or cold will kill them ; we can grow 
 them in large quantities, and study the chemi- 
 
THE STORY OF THE BACTERIA. 39 
 
 cal compounds which result from their life 
 processes. We can apply to them various 
 chemical substances which are called germi- 
 cides, or disinfectants, and find out to which 
 of these and in what strength they most readily 
 succumb. 
 
 In this way a large number of different 
 species of bacteria have been studied, and 
 these have been arranged in groups which 
 have some characters in common. So that 
 already, although the study of the bacteria by 
 the new methods is of very recent date, we 
 have the outline of analysis tables, something 
 like those made for the identification of the 
 higher plants in Gray's " Botany," for instance, 
 by the use of which the student can identify 
 certain of the better known forms which he 
 may come across in his studies. 
 
 The nomenclature in bacteriology is still in 
 a rather chaotic condition, but a beginning has 
 been made. The term bacteria (singular, bac- 
 terium) applies to the whole class of organisms 
 of whatever shape. They are also sometimes 
 called " germs." Micrococcus is the generic 
 name of the most common forms of the spher- 
 
40 THE STORY OF THE BACTERIA 
 
 oidal bacteria. Thus there is a species of mi- 
 crococcus which produces a yellow color when 
 it is growing in masses. This species is called 
 Micrococcus luteus. There is another species 
 of micrococcus which when growing has the 
 peculiarity of a grouping of the micrococci, or 
 cocci, as they are sometimes called, in fours ; 
 this species is called Micrococcus tetragenus. 
 
 Another genus among the spheroidal bac- 
 teria is called Streptococcus, because the little 
 balls tend to cling together and form longer 
 and shorter chains as they grow. Then among 
 the rod-shaped bacteria the most common ge- 
 nus is called Bacillus (plural, bacilli), and some 
 of the species of this genus are among the 
 most common and abundant forms. 
 
 Thus with a temporary and provisional sys- 
 tem of classification, the work of studying 
 and describing the bacteria is steadily going 
 on. And if to see and describe living beings 
 on which no human eye has ever rested before 
 be satisfying, it will be long before the sighs 
 of bacteriological Alexanders are heard in this 
 unseen world, whose very shores have been 
 barely touched by the new explorers. 
 
CHAPTER IV. 
 
 SOME BACTERIAL CURIOSITIES. 
 
 MOST travellers, and some people who 
 stay at home, too, have now and then 
 been mystified and delighted, when not fright- 
 ened, to see in the night-time that wavering, 
 cold, uncanny, but beautiful light, sometimes 
 tinged with the most exquisite green or blue, 
 which is commonly called phosphorescence. 
 Sometimes it is seen in decaying plants or 
 wood ; sometimes bays or inlets of the sea are 
 fairly luminous with it. The surface of dead 
 fish and of meat and various kinds of vegeta- 
 bles often become so bright as to illuminate 
 the storage rooms in which they lie. 
 
 Some time since there was brought to the 
 laboratory for examination a cluster of sausages 
 which had been destined to grace a boarding- 
 house breakfast-table. To the consternation 
 of the maid who went into the dark cellar 
 
 41 
 
42 THE STORY OF THE BACTERIA. 
 
 for them in the early morning, there hung in 
 the place of the sausages a fiery effigy which 
 seemed to her more like the quondam spirits 
 of their mysterious ingredients than the unc- 
 tuous homely friend of the homeless boarder. 
 The explanation of this is now simple 
 enough without recourse to the supernatural ; 
 for it has been recently shown that this curious 
 light which various organic substances emit is 
 due, in many cases at least, to the enormous 
 numbers of certain kinds of bacteria which are 
 present on their surfaces, hard at work feeding 
 on the organic compounds which are present 
 and undergoing decay. Pure cultures of these 
 singular bacteria have been made and culti- 
 vated in considerable quantities. These bac- 
 terial masses, together with the tubes in which 
 they were growing, have been placed in a dark 
 room with an open watch beside them, and 
 bacterial masses, tubes, and all actually photo- 
 graphed by their own light, the pointers of the 
 watch showing distinctly the time of day. So 
 it would seem that this cousin of the will-o'-the- 
 wisp no doubt often mistaken for him is no 
 malevolent genius after all, but a quiet little 
 
THE STORY OF THE BACTERIA. 43 
 
 citizen working- away as diligently as he can 
 to make the world more comfortable for his 
 betters. 
 
 It has long been known by the makers of 
 beverages that alcohol is formed in certain 
 sugary mixtures by a process called fermenta- 
 tion, and that this tearing to pieces of the 
 sugar into other compounds, one of which is 
 alcohol, is accomplished by a little living or- 
 ganism called yeast, closely related to the 
 bacteria. In the earlier days of beer- and wine- 
 making it was often found that the beer did 
 not work or ferment properly, and that wine 
 would get sour or bitter. We now know that 
 these irregularities are due to the fact that 
 certain kinds of bacteria are apt to get into 
 the wine or beer during the manufacture, and 
 when they do a bitter struggle for food goes 
 on between the yeasts and the bacteria ; or 
 the latter may bide their time, and later in the 
 process begin to grow and produce very unde- 
 sirable compounds in the fluids. So the man- 
 ufacturer has to be on the alert, and at the 
 right moment come to the rescue of his army 
 of servitors, the yeast plants, and introduce 
 
 
 ^ r r 
 
 
44 THE STORY OF THE BACTERIA. 
 
 into his beer some chemical substance which 
 is innocuous to them but deadly to the intrud- 
 ing bacteria. Or he may raise his wine at a 
 certain period to such a temperature as will 
 suffice to kill the bacteria but not injure the 
 flavor of the already fermented juice. Here 
 for the first time we see the bacteria coming 
 in conflict with the purposes of their earth- 
 neighbor man. 
 
 Some of the bacteria are great lovers of 
 oxygen, and if they are shut up in a little cell 
 containing a few drops of water in which a bub- 
 ble of air has been enclosed, after a while it will 
 be found that those forms which are caoable 
 of locomotion have made their way from 
 all parts of the fluid, which is a veritable ocean 
 to them, and are closely clustered around the 
 air bubble, jostling and bumping against one 
 another in the most reckless way. It seems 
 almost as if this rush towards the oxygen were 
 an evidence of volition in its simplest form 
 way down on the lowest border-line of life. 
 
 Some forms of bacteria are exceedingly in- 
 vulnerable to the action of cold, and can not 
 only move actively about in very cold water, 
 
THE STORY OF THE BACTERIA. 45 
 
 but can remain alive for long periods fast 
 frozen in a mass of ice. Now a very curious 
 thing has been noticed in the ice which is 
 gathered in these regions and which we use 
 for domestic purposes, and that is, that the so- 
 called bubbly streaks which we usually see in 
 our ice blocks contain, as a rule, many more 
 bacteria than does the transparent ice close by. 
 It has been found, on cultivating the bac- 
 teria from the bubbly streaks, that the species 
 which was most abundant here is an oxygen 
 lover, and is also very mobile. Now the bub- 
 bles which collect in streaks or layers in the 
 ice collect during the daytime, or when the ice 
 is not freezing very fast below, and there is 
 time for the a$r-seeking bacteria to gather 
 around them in great numbers. But now, 
 when a clear night or a cold snap comes on, 
 the ice closes around both bubbles and bacte- 
 ria, and we have formed, to use the language 
 of the geologist, an air and fossil-bearing 
 stratum. Only our bacterial fossils are not 
 dead, and all we have to do in order to find 
 out what forms of life were present in our suc- 
 cessive geological periods, limited perhaps 
 
46 THE STORY OF THE BACTERIA. 
 
 only by a night, is to melt a bit of the ice, mix 
 it with our culture gelatin, and in a day or two 
 we shall have a whole garden of growing 
 plants, which we can study at our leisure. 
 
 Among the most curious things which the 
 bacteriologist has to exhibit in his bacterial 
 conservatory is the color-forming species. It 
 is only when they are growing in masses, of 
 course, that enough color is formed to be visi- 
 ble ; but then one may see in the little slimy 
 masses which cover the surface of the food or 
 culture media in the tubes, every color of the 
 rainbow and many variations in hue. Some- 
 times not only is the bacterial mass itself 
 brilliantly colored, but some of the chemical 
 substances which they form as they grow 
 permeate the gelatin and give it a beautiful 
 fluorescence, green or red. 
 
 The writer was not long ago standing be- 
 side a supper-table, whose sole floral decora- 
 tion was a bunch of large, exquisitely tinted 
 chrysanthemums, when a friend remarked upon 
 the patience and skill which had been required 
 to develop this magnificent flower by artificial 
 selection from its simple and homely ancestor, 
 
THE STORY OF THE BACTERIA. 47 
 
 and queried in a quizzing way how long it 
 would be before somebody would be trying to 
 modify the colors of some of the bacteria by 
 the well-known horticultural methods. His 
 idea was a clever one, but he was behind the 
 times, for already a German bacteriologist 
 had, starting with a deep purple-forming spe- 
 cies of bacteria, and selecting and replanting 
 the lighter-colored colonies, at last obtained 
 cultures which were nearly white, but were in 
 other respects essentially the same. Thus the 
 great and far-reaching principles of natural 
 selection, in accordance with which life, slowly 
 emerging from its primeval simplicity, at last 
 came to be manifested in that grand scale of 
 living beings at the top of which man stands 
 supreme, are still to be traced way down among 
 the invisible organisms which typify the earliest 
 and simplest expression of life. 
 
 But certain of these color-forming bacteria 
 are sometimes very disagreeable intruders 
 upon domestic life. Occasionally, without 
 warning, the milk of a particular dairy sud- 
 denly develops a very uncanny deep-blue 
 color, which, like an epidemic, spreads to all 
 
48 THE STORY OF THE BACTERIA. 
 
 the milk which is stored in special rooms. 
 This occurrence, for a long time a disagreeable 
 and costly mystery, is now known to be due to 
 a tiny bacterium of the genus Bacillus, which, 
 floating about in the air with the dust, from 
 time to time infects rooms, and, falling into 
 the milk, grows there, producing the blue 
 coloring matter. 
 
 Sometimes milk gets red instead of blue, 
 and then the change is due to another form of 
 bacteria floating with the dust. Bread, too, 
 may become infected in the same way, and the 
 dough set aside in bake-shops overnight to 
 rise has not infrequently been found in the 
 morning resplendent with colors which fairly 
 rivalled those of the rising sun. 
 
 There is a species of bacteria in every good 
 collection, and a veritable Nestor among the 
 forms known to man, which has a curious 
 ecclesiastical history. Among all the innu- 
 merable natural phenomena which, by their 
 striking character, infrequent occurrence, and 
 lack of apparent cause, were in early times 
 relegated to the domain of the supernatural, 
 none perhaps was more strange and uncanny 
 
THE STORY OF THE BACTERIA. 49 
 
 than the sudden appearance on the moist sur- 
 faces of articles of food of little bright-red 
 shiny droplets, which, gradually spreading, at 
 length formed large shiny, deep, rich-red 
 masses, looking very like drops, or masses, or 
 clots of blood. The story is long and tragic 
 of the dire calamities, unmentionable crimes, 
 and swift retributions which these strange ap- 
 pearances of blood were supposed to fore- 
 shadow. 
 
 This miracle of the bleeding Host has 
 appeared again and again in the hands of the 
 priestly defenders of the faith as a most potent 
 evidence of divine intervention with the affairs 
 of men. The consecrated wafer placed over- 
 night in the moist and bacteria-laden air of 
 the church edifice, would in the morning be 
 found besprinkled with bright-red drops. 
 What could it be but blood ? No human 
 hand could have come near the place, and so 
 what else could be believed but that it was 
 from the hand of God? It was one of those 
 early miracles in which both priest and layman 
 could alike share in believing with perfect 
 honesty. The divine finger pointed, but to 
 
50 THE STORY OF THE BACTERIA. 
 
 what, it was the office of the priest to say. 
 How many lives were sacrificed and homes 
 destroyed through that most honest of eccle- 
 siastical delusions, the miracle of the bleeding 
 Host, it were useless now even to conjecture. 
 
 To-day we cultivate in our tubes the tiny 
 bacteria which, growing in masses, made the 
 drops of blood, and the last elements of 
 romance and tragedy seem to disappear from 
 the story as we name them Bacillus prodigi- 
 osus. 
 
 There are some species of bacteria which 
 are mortal enemies and cannot live together, 
 one species killing out the other almost as 
 soon as they come in contact. The details of 
 this invisible mimic warfare we do not yet 
 understand, nor do we know what are the 
 weapons with which it is carried on. It is 
 probable that it is in virtue of some poison 
 which they form as they live and grow that the 
 victors gain possession of the field. 
 
 On the other hand, there are two or three 
 instances of a sort of one-sided Damon-and- 
 Pythias story among these creatures ; for in 
 the attempts to isolate the species by culture it 
 
THE STORY OF THE BACTERIA. 5! 
 
 has been found that sometimes two species can 
 be isolated and grow together, but if the at- 
 tempt be made to separate them, one of them 
 always dies. The exact nature of this friendly 
 tie is still unknown. Perhaps in this case the 
 material which is set free by one species as it 
 feeds and grows is the only thing which its 
 associate can live and thrive upon. 
 
CHAPTER V. 
 
 THE BACTERIA AS MAN'S INVISIBLE FOES. 
 
 WE have seen that the bacteria in general 
 are not only curious and interesting 
 as objects of study, but in the work which they 
 are ceaselessly and silently doing they are ab- 
 solutely indispensable to the continuance of 
 the higher forms of life upon the earth. But 
 unfortunately there is another darker side to 
 the picture. Among the myriads of useful as 
 well as harmless bacteria, we have lately 
 learned that there are a few forms which find 
 the most favorable conditions for their life and 
 growth in the bodies of men and some of the 
 higher animals. 
 
 They do not grow well in nature as other 
 bacteria do, nor do they thrive on ordinary 
 decomposing organic matter. They look very 
 much like the more common harmless bacteria, 
 some being little balls, some rods, and some 
 
 52 
 
THE STORY OF THE BACTERIA. 53 
 
 spirals. Like other bacteria, they grow at the 
 expense of the materials with which, under 
 favorable conditions, they come in contact, and 
 like them they produce new chemical com- 
 pounds as the result of their life processes. 
 When they get into the human body, the dif- 
 ferent forms grow in different ways, and pro- 
 duce different kinds of chemical compounds, 
 and this growth or the poisonous chemical 
 compounds which are produced cause disease. 
 
 Bacteria which can grow in the body and 
 produce deleterious effects there are called 
 pathogenic or disease-producing bacteria. The 
 poisonous chemical compounds which they set 
 free as they grow, are called ptomaines. 
 
 Now, before we try to comprehend how 
 disease can be produced by bacteria, we ought 
 to understand what disease is. 
 
 We have seen in the first chapter that the 
 human body is made up of several communi 
 ties of cells, each community having acquired 
 the power of doing some special thing for the 
 good of the body as a whole, and that these 
 cell communities are all co-ordinated so as to 
 act in harmony. We have seen that these 
 
54 THE STORY OF THE BACTERIA. 
 
 cell communities which make up this wonder- 
 ful mechanism are all originally derived from 
 a single living cell, the ovum. 
 
 What this mysterious thing is which we call 
 life, which from the original cell, the ovum, is 
 imparted to all the myriad specialized cells 
 which spring from it as the body grows ; what 
 it is which determines that from one of two 
 cells which under the most powerful of micro- 
 scopes look exactly alike there shall develop a 
 man, and from the other an animal, we simply 
 do not know. We theorize, we speculate, we 
 draw analogies, we give names, but at the 
 end we conclude that we must wait still for 
 more light. We do know, however, that this 
 self-built cellular mechanism, the body, which 
 is alive, has in it the power of self-renewal : 
 the power, when once started, to go on doing 
 the various things for which it is fitted for a 
 certain time, provided that the proper external 
 conditions are maintained. But sooner or 
 later the machinery begins to creak and trem- 
 ble, sometimes in one part, sometimes in 
 another, sometimes everywhere, and gradually 
 or suddenly that combination of activities 
 
THE STORY OF THE BACTERIA. 55 
 
 which we call life disappears, and the worn-out 
 mechanism for the first time since it came into 
 being is still. This is death. There is no 
 disease, but, as we are apt to say not because 
 it means much, but because we think we must 
 say something, an exhaustion of the vital 
 forces. The mechanism is worn out, and so 
 can no longer develop out of food and air the 
 self-renewed impelling force. It is death from 
 old age. But this is comparatively infrequent. 
 If the proper food, air, and surroundings are 
 maintained, the various co-ordinated cell com- 
 munities which we call liver, brain, kidneys, 
 lungs, integument, and so forth, provided they 
 are properly set going in the first place, have 
 not only the power to go on doing their work, 
 but they have a well marked capacity for over- 
 coming and resisting deleterious agencies of 
 one kind and another, a sort of health inertia. 
 The muscle cells do make shift to contract 
 even though their food supply be temporarily 
 scanty ; the blood cells will carry a certain 
 amount of oxygen in their ceaseless rounds of 
 visits to the tissues, though the air from which 
 they get it through the lungs be as foul and 
 
56 THE STORY OF THE BACTERIA. 
 
 meagre as it is in some of our fashionable 
 theatres and churches and school-rooms. And 
 if certain cells or groups of cells should be 
 forced to work awry, they always tend to get 
 back to their proper work and conditions even 
 against great obstacles, just as soon as they 
 can. 
 
 Even when large numbers of cells or cell 
 groups are entirely removed from the commu- 
 nity, as by an injury, new cells can form out 
 of those which are left, or the duties of the 
 lost cells are assumed and may be permanently 
 maintained by their fellows. Patriotism and 
 esprit du corps are very markedly typified in 
 the cell communities of which our bodies are 
 made up. 
 
 When important cell communities are seri- 
 ously injured or changed in structure so that 
 they cannot do well the things which they 
 ought to do, or when they fail to act in har- 
 mony, through some fault of their own or some 
 disorder in the co-ordinating mechanism, the 
 failure in what we may term the rhythm of the 
 body's activities constitutes what we call disease. 
 
 The part which may be the seat of the dis- 
 
THE STORY OF THE BACTERIA. 57 
 
 ease is as varied as are the organs and tissues 
 of which the body is composed. 
 
 The disturbances in the activities of the 
 body which result from these changes in the 
 structure and action of the various parts have 
 been so long studied that the educated physi- 
 cian is usually able to tell from certain irregu- 
 larities of the body's activities what part or 
 parts it is which are affected. In many cases 
 the physician does, in some he does not, know 
 what the exact cause is of the disturbance. In 
 some cases, when the cause of the disturbance 
 is known, he can remove it either by directing 
 a change in the habits or by the administration 
 of drugs, and then the tendency of the cell 
 communities of the body to get back into their 
 proper condition of themselves alone will 
 restore health. Sometimes this inherent ten- 
 dency is aided by the use of medicines. Some 
 of the body's disturbances tend to pass away 
 of themselves after a longer or shorter period, 
 if they are not so severe as to destroy life. 
 Under these conditions the duty of the physi- 
 cian may be only to aid the body by food and 
 stimulants in the work which it is doing itself. 
 
58 THE STORY OF THE BACTERIA. 
 
 And so through the long list of ills which come 
 upon the human frame, from known or un- 
 known causes the wise physician guides and 
 aids the natural recuperative tendencies of the 
 body cells. 
 
 Among all the varied changes in structure 
 and disturbance in activities of the body which 
 thus constitute disease there are, as we have 
 seen, several, and these most important ones, 
 which have recently been proven to be caused 
 by bacteria. To some of these we must now 
 turn our attention so as to learn how the dis- 
 turbances are brought about, and what we 
 may do for ourselves to avoid them. 
 
CHAPTER VI. 
 
 THE BACTERIA OF SURGICAL DISEASES. 
 
 ONE of the greatest dangers associated 
 with injuries and wounds of the body, 
 whether inflicted by accident or made by the 
 knife of the surgeon in necessary operations, 
 is the liability to what is known as blood 
 poisoning. 
 
 So great is this danger, that it has long been 
 known that in war a great many more lives 
 are lost from blood poisoning than by bullets 
 or cannon-balls. The cause of this form of 
 disease, which is so apt to complicate wounds, 
 was for a long time entirely unknown. Then, 
 as these wounds were apt, in blood poisoning, 
 to be foul and bad-smelling, it was concluded 
 that the trouble might be that dirt or filth of 
 some sort got into them and so set up the dis- 
 ease. 
 
 What the particular thing was, whether 
 
 59 
 
60 THE STORY OF THE BACTERIA. 
 
 bacteria or something else, which so gained 
 entrance to the body, no one knew. But the 
 surgeons did not wait until they should know 
 all about the cause of the trouble, but began 
 to apply to the wounds such materials as would 
 actually kill germs, or, at any rate, keep the 
 wounds free from putrefactive changes. Car- 
 bolic acid, dissolved in water, was found to be 
 efficient in this way in washing the wounds. 
 
 Then, as it seemed more and more as if the 
 trouble were due to living germs falling upon 
 the wounds from the air with the dust, it be- 
 came the practice, when surgical operations 
 were being done or wounds dressed, to spray 
 carbolic in the air about the operator's hands 
 and over his instruments and upon the wounds, 
 and when the bandages were put on to seal 
 them in tightly, so that no germs could gain 
 access to the wound while the healing went 
 on. All this time the particular species of 
 bacteria which produced the trouble remained 
 entirely unknown ; indeed, it was only an 
 hypothesis that the disease was due to germs 
 at all. 
 
 A great deal of careful laboratory work has, 
 
THE STORY OF THE BACTERIA. 6 1 
 
 however, been done recently on this subject, 
 and a great many animal experiments made, 
 until now we know not only that blood poison- 
 ing but abscesses, erysipelas, and many other 
 less serious inflammations are caused by bac- 
 teria. We have found out, furthermore, that 
 there are two particular species which cause 
 the trouble in the great majority of cases. 
 
 Both of these bacteria are little balls or 
 micrococci. One of them, as it grows, tends 
 io form chains, and so is called Streptococcus ; 
 the other tends to group itself in clusters a 
 little like a bunch of grapes, and so is called 
 Staphylococcus. 
 
 Now, it has been further found that these 
 two forms of bacteria are quite abundant 
 where people are gathered, mostly in dirty 
 places ; sometimes where the healthy, but espe- 
 cially where sick people are crowded together, 
 as in hospitals, They are found in small num- 
 bers floating with the dust in the air, where 
 dust lodges, and often in the mouths and on 
 the clothing of the people themselves. 
 
 It is thus evident how the wound diseases, 
 such as blood poisoning, can come about, for 
 
62 THE STORY OF THE BACTERIA. 
 
 wherever the dust falls on the open surfaces of 
 the. wounds or on any thing which comes in 
 contact with them, and the living bacteria 
 lodge, they may, if not destroyed, commence 
 to grow, and not only by the poisonous mate- 
 rials which they form as they grow, interfere 
 with the healing of the wounds, but they may 
 get into the blood and be carried to various 
 parts of the body, there growing and produ- 
 cing sometimes fatal results. 
 
 It is one of the greatest practical triumphs 
 of science in modern times that the surgeon 
 can now so carefully plan out his operations 
 and treatment of wounds, that not only is 
 blood poisoning, as it used to prevail but a 
 few years ago, the greatest rarity among edu- 
 cated and skilful surgeons, but the most ex- 
 tensive operations, such as opening the great 
 cavities of the body, may now be done, when 
 they are necessary to save life or make it 
 endurable, with very little risk of the frightful 
 dangers which formerly attended such pro- 
 cedures. 
 
 Childbed fever, which in former times 
 claimed so many victims under especially lam- 
 
THE STORY OF THE BACTERIA. 63 
 
 entable circumstances, and which used some- 
 times to spread with frightful rapidity among 
 women whose confinement took place in hos- 
 pitals, is now of comparatively rare occur- 
 rence, because the educated physician knows 
 what the particular element of danger is and 
 how to avoid and combat it. For it has been 
 found that childbed fever is really a form of 
 blood poisoning, due to the same germs as 
 induce the disease in ordinary wounds. 
 
 Dr. Oliver Wendell Holmes, early in his 
 career, became convinced that the poison caus- 
 ing childbed fever could be carried on the 
 clothes of the physician from one patient to 
 another. What the poison was he could not 
 even fairly conjecture, but of the fact he was 
 certain. In spite of much opposition and ridi- 
 cule he urged his views, and many lives were 
 ultimately saved and epidemics stayed because 
 of his persistency in making known his facts. 
 To-day we not only know that all that he 
 urged was true, but the poison which he as- 
 sumed but could not see has been proved to 
 be bacteria, and we can now cultivate them 
 in tubes and know exactly what will most 
 
64 THE STORY OF THE BACTERIA. 
 
 surely destroy them. While literature owes 
 much to the wit and cleverness of the genius 
 of the breakfast-table, science and humanity 
 are not less debtors to the zeal and pertinacity 
 of the young doctor, who still declared for his 
 beliefs, though his more aged and then more 
 renowned confreres applied to him many terms 
 of opprobrium and disrespect. 
 
 Now let us look a little more closely at the 
 way in which these tiny organisms cause in- 
 flammation, suppuration, or the formation of 
 pus and blood poisoning. We have seen in 
 the first chapter that although most of the 
 cells of the body have assumed special forms 
 and powers as the body develops out of its 
 embryonic stage, there are some cells which 
 scarcely seem to have got beyond the stage in 
 which the simplest of the unicellular organ- 
 isms, such as the amoeba, belong. The most 
 prominent of these lowly organized cells in 
 the body are the white blood-cells or, leucocytes 
 as they are called. Under ordinary conditions 
 they go circling round the blood-vessels along 
 with the red blood-cells, or, crawling out of the 
 blood-vessels, slowly make their way around 
 
THE STORY OF THE BACTERIA. 65 
 
 in the smaller spaces in the tissues. Exactly 
 what they do under these circumstances we do 
 not know. There is some reason for think- 
 ing that they act to some extent as scaven- 
 gers, and when they come across a particle of 
 worn-out or foreign material in the tissues, take 
 it into themselves, just as amceba does its food 
 in water, and either digest it or carry it back 
 to those parts of the body in which waste ma- 
 terial is systematically disposed of. 
 
 But let an injury such as an open wound 
 occur, and the whole attitude of these leuco- 
 cytes changes. They get out of the blood- 
 vessels with all speed, in greater or less num- 
 bers as the occasion may demand, and gather 
 about the edges of the wound, and after a 
 time they, together with some other cells of 
 the injured tissue, change their shape and 
 character, and actually form, with the aid of 
 the blood-vessels near-by, a mass of new tis- 
 sues, which replaces that which was lost by 
 the injury, and so permanently binds the edges 
 of the wound together. Sometimes these white 
 blood-cells gather in much greater quantities 
 about the wound than is necessary, and then 
 
66 THE STORY OF THE BACTERIA. 
 
 they are thrown off in the form of a material 
 which we call pus. 
 
 Now to come back to the bacteria which we 
 are studying. When these bacteria get into the 
 tissues, they may begin to grow, and as they 
 do so they produce a small amount of a poison 
 which we call a ptomaine, and this poison act- 
 ing injuriously on the tissues where it is 
 formed, the white blood-cells gather about it 
 just as they would about a wound. If the 
 bacteria continue to grow and multiply, the 
 white blood-cells may accumulate more and 
 more and die, the tissues may break down, 
 and so an abscess may be formed. Some- 
 times the germs get into the blood and are 
 carried to various parts of the body, and 
 wherever they lodge abscesses may be formed, 
 and this constitutes one of the most dreaded 
 forms of blood poisoning. 
 
 Now what do the white blood-cells accom- 
 plish under these circumstances ? Many be- 
 lieve, although the matter has not been quite 
 settled yet, that when these bacteria get into 
 the tissues and begin to grow, the arrival of the 
 white blood-cells upon the scene signalizes the 
 
THE STORY OF THE BACTERIA. 67 
 
 commencement of a life-ancl-death struggle be- 
 tween the bacteria and the cells. The cells 
 attempt either to swallow and thus kill and 
 digest the bacteria, or to so closely surround 
 them as to cut off their oxygen and food sup- 
 ply and so destroy them. The bacteria, on 
 the other hand, so long as they can grow and 
 proliferate, produce a poison which may kill 
 the white blood-cells and break up the other 
 tissues round about. 
 
 There is much reason for believing that this 
 is what actually occurs : that the resisting ca- 
 pacity of the body to the incursions of these 
 invisible organisms is largely resident in these 
 lowly organized cells, which in carrying on 
 their simple cellular activities assume the role 
 of defenders of the body against the bacterial 
 invaders. If the conditions are favorable for 
 them the white blood- and other cells may get 
 the upper hand of the bacteria and stop their 
 growth or kill them all off and thus avert the 
 danger. If, on the other hand, the cells are 
 not vigorous enough to resist the poison elimi- 
 nated by the bacteria and themselves succumb 
 to its influence, the way is opened to the spread 
 of the infecting germs. 
 
68 THE STORY OF THE BACTERIA. 
 
 It sometimes happens that so extensive a 
 growth of the bacteria occurs in some local 
 region of the body and so much of the soluble 
 poison is produced that although the bacteria 
 may not themselves get generally distributed 
 the poison which they furnish may enter the 
 circulation, and so produce in distant parts of 
 the body most serious disturbance or even 
 cause death. These bacteria apparently do no 
 harm when they lodge upon the uninjured sur- 
 face of the body, but only when they get into 
 the tissues through an injury or lodge upon sur- 
 faces of the respiratory or digestive tract which 
 are already the seat of disease. 
 
 This is in brief the story of the bacteria 
 which most commonly produce the common 
 inflammations of the tissues, the complications 
 in the healing of wounds, and the varying 
 phases of blood poisoning. As pus in greater 
 or less quantity is apt to be produced under 
 these circumstances, these bacteria are called 
 the pus-forming or pyogenic bacteria. Some 
 other bacteria may occasionally produce simi- 
 lar effects, but those which have been described 
 are the most common and important. 
 
THE STORY OF THE BACTERIA. 69 
 
 The effects which these as well as other dis- 
 ease-producing bacteria may produce in the 
 body vary considerably under different condi- 
 tions. Sometimes the general condition of the 
 body is such that it seems to furnish very 
 favorable soil for their proliferation or is espe- 
 cially vulnerable to their action. Sometimes 
 the particular germs which gain access seem to 
 be especially virulent, perhaps from their inhe- 
 rent vigor or from conditions which we know 
 nothing about. We are in these diseases deal- 
 ing with poisons of the human body, but with 
 self-propagating poisons which from an almost 
 infinitesimal amount may grow to such quanti- 
 ties as will fairly overwhelm the body. 
 
CHAPTER VII. 
 
 THE BACTERIA WHICH CAUSE CONSUMPTION, OR 
 TUBERCULOSIS. 
 
 MORE than one seventh of all the people 
 who die are carried off prematurely by 
 consumption, or tuberculosis. But it is only 
 within the present decade that we have had 
 any definite knowledge as to the cause of the 
 disease. For a great while physicians have 
 known a great deal about it. They have be- 
 come very expert in detecting its advent and 
 in tracing its course, and came long ago to 
 know but too well whither it tended. The 
 disease was usually regarded as hopeless, and 
 its treatment was entered into rather for hu- 
 manity's sake than in the expectation of in- 
 ducing a cure. To-day the aspect of affairs 
 has greatly altered. We know that tubercu- 
 losis is caused, and caused alone, by exceed- 
 ingly minute, rod-shaped bacteria, which, in 
 
 79 
 
THE STORY OF THE BACTERIA. 
 
 one way or another, gain access to the body. 
 When there, if the conditions are favorable, 
 they tend to grow, and as they do so there 
 form about them little masses of new tissue, 
 which are called tubercles. The most common 
 seat of the disease is the lungs, but it may oc- 
 cur in any part of the body. 
 
 It is not necessary for our purposes to enter 
 further into the details of the progress of the 
 disease. It is but too well known to nearly 
 every one who has seen one and another pass 
 away from sight under its insidious progress. 
 It is our purpose here only to show how the 
 disease is commonly acquired. 
 
 Not all persons are equally liable to be at- 
 tacked by tuberculosis. There seems to be a 
 certain condition of the body cells which pre- 
 disposes to the disease, and this predisposition 
 is in the most marked degree hereditary. We 
 do not know yet in what this predisposition 
 consists. We believe that when the tubercle 
 bacillus gets into the healthy body the cells of 
 the part in which it lodges in some way tend 
 to resist its growth, or afford unfavorable con- 
 ditions for its development. The temporary 
 
72 THE STORY OF THE BACTERIA. 
 
 hypothesis around which we try to crystallize 
 our accumulating knowledge is that in heredi- 
 tary predisposition to tuberculosis this in- 
 herent resisting capacity of the cells to the 
 incursions of the germs is in some way dimin- 
 ished. This is very indefinite, it is true, but 
 it is the best we can do at present. We know 
 that tuberculosis is never caused by any other 
 thing than the tubercle bacillus, and that even 
 in persons predisposed by inheritance or other- 
 wise to the disease it cannot occur unless this 
 particular germ gets into the body from out- 
 side. The germ itself has rarely, if ever, been 
 shown to be directly inherited. If, therefore, 
 we could keep this particular germ away from 
 human beings, there would be no more tuber- 
 culosis, no matter what the inherent tendencies 
 of the individual might be. 
 
 Let us now see what our knowledge teaches 
 us as to the sources of infection with the 
 tubercle bacillus. In the first place, we should 
 not forget that as the early stages of the dis- 
 ease are often very insidious in their progress, 
 and as an individual may actually have a 
 moderate degree of tubercular disease for a 
 
THE STORY OF THE BACTERIA. 73 
 
 long time without the slightest disturbance of 
 the general health, and, furthermore, as the 
 germs in greater or less number are widely 
 distributed in densely inhabited regions, it is 
 usually quite impossible to say in any particular 
 case what the source of the infection was. 
 
 Cattle, in this as in many other countries, 
 are very frequently the victims of tuberculosis, 
 which is caused by the same germ as is the 
 disease in man. As the living tubercle bacilli 
 may be contained in the milk from diseased 
 cows, and in the flesh of affected cattle, it 
 appears that here is an important source of 
 danger. 
 
 It is almost inconceivable that any man not 
 wholly given over to the spirit of the Devil 
 should be capable of sending into the market 
 meat from tubercular cattle, if he is aware of 
 it. Yet there is reason for believing that a 
 very considerable amount of such diseased 
 meat is actually sent into our large towns 
 every year, with the full knowledge of some 
 of the unscrupulous dealers, and probably 
 consumed, usually by the poorer and more 
 ignorant classes. Thorough cooking of such 
 
74 THE STORY OF THE BACTERIA. 
 
 diseased meat would kill the bacilli, but a large 
 amount of meat is everywhere commonly con- 
 sumed uncooked, or but partially cooked, in 
 the form of sausages or other minced messes. 
 
 Infection with the tubercle bacillus in the 
 intestinal canal is not so liable to occur as in 
 some other parts of the body, even among 
 persons predisposed to the disease. But, 
 nevertheless, the danger from tubercular milk 
 and meat is a very real and a growing one. 
 
 The most frequent seat of affection with the 
 tubercle bacillus is the lungs, and the most 
 common way in which the germs gain access 
 to the respiratory passages is by being 
 breathed in with the dust which is floating in 
 the air in rooms or regions where tubercular 
 persons have been. In other words, tubercu- 
 losis is most commonly acquired by indirect 
 transmission of the tubercle bacilli from man 
 to man through the dust of the air. 
 
 Now the most common way in which the 
 tubercle bacilli get into the air from consump- 
 tive people is this : the little masses of new 
 tissue which form in the lungs where the tu- 
 bercle bacilli are, are not well supplied with 
 
THE STORY OF THE BACTERIA. 75 
 
 blood, and for this and other reasons they are 
 apt to become friable and break down, and 
 then little particles of them are apt to be 
 coughed up and discharged in the sputum. 
 But this broken-down material frequently con- 
 tains large numbers of living tubercle bacilli. 
 Now, if the material which consumptive per- 
 sons cough up and spit out were always de- 
 stroyed at once by being burned or received 
 into a dish of carbolic acid or some other effi- 
 cient disinfectant or germicide, one of the 
 greatest dangers of the spread of the disease 
 would be removed. But unfortunately this is 
 in fact very rarely done. Thousands of con- 
 sumptives are walking about the streets of our 
 large towns or visiting places of assembly, who 
 discharge the infectious material coughed up 
 from the lungs upon the pavements or floors. 
 This dries, and shortly is ground up, and takes 
 its place among the rest of the floating du^t of 
 the air. 
 
 Essentially the same thing takes place in 
 rooms in which consumptives are confined if 
 intelligent precautions are not taken to destroy 
 or convey away the discharged material. It 
 
76 THE STORY OF THE BACTERIA. 
 
 has been found by actual experiment that a 
 considerable number of living tubercle bacilli 
 may be lodged, together with other dust par- 
 ticles, high up on the walls of hospital wards 
 in which consumptives are unintelligently 
 cared for, in situations to which they could 
 have been conveyed only through the air as 
 ordinary dust is. The same material allowed 
 to dry on handkerchiefs may in a similar way 
 become a source of danger, not only to others, 
 but may cause a fresh infection of the patient 
 himself. 
 
 It is very important to remember that it is 
 only when this discharged material is allowed 
 to dry that it, under ordinary circumstances, 
 becomes a source of infection through the air. 
 Bacteria never rise from thoroughly moist 
 surfaces. One might spread a thick layer of 
 living bacteria of any kind, no matter how in- 
 fectious, over an exposed surface, and, pro- 
 vided it was kept thoroughly moist, might 
 breathe with impunity the air sweeping in 
 strong currents over it, because the germs 
 always cling most tenaciously to such surfaces. 
 Of course a current of air strong enough to 
 
THE STORY OF THE BACTERIA. 
 
 sweep the particles of fluid bodily off from 
 their position would be efficient in spreading 
 the infection. The important point which this 
 statement emphasizes is that the breath of tu- 
 bercular persons is not infectious ; the air itself 
 passing over the moist surfaces of the respira- 
 tory passages and the mouth carries no germs, 
 The act of kissing, however, might lend itself 
 most efficiently to the transmission of the 
 infection. 
 
 Now all these facts are extremely disagree- 
 able both to hear about and to tell, and they 
 can only be infinitely distressing to the victims 
 of tuberculosis and to their friends and associ- 
 ates ; but all the same they are facts, stubborn, 
 abiding, and significant. The sooner we rec- 
 ognize the truth that every consumptive person 
 may, if proper precautions are not taken, be an 
 actual and active source of infection, not only to 
 those who immediately come in contact with 
 him, but to those who, either where he is, or 
 where he has been, are forced to breathe dust- 
 laden air, the better will it be for all concerned. 
 
 Now of course no intelligent person would 
 infer from this statement of facts regard- 
 
78 THE STORY OF THE BACTERIA. 
 
 ing the sources of infection with tubercle 
 bacilli through the air, that everybody who 
 goes upon the street or enters a hospital or 
 a theatre is going, or is even liable, to ac- 
 quire tuberculosis. For, in the first place, the 
 infecting material, even under the worst con- 
 ditions, is enormously diluted by the circu- 
 lating air, so that the individual chances of 
 coming in contact with the dangerous material 
 are slight. In the second place, the average 
 healthy individual is not predisposed to the 
 disease at all, and could be affected only under 
 especially favorable conditions. Third, the 
 amount of infecting material is apt, in trans- 
 mission by the air, to be small, and this is a 
 condition which diminishes the chances of 
 danger from such exposure. Finally, every indi- 
 vidual has in his respiratory tubes an arrange- 
 ment of tiny cells whose free surfaces are cov- 
 ered with little hair-like processes called cilia. 
 These are ceaselessly waving to and fro, and 
 tend to sweep up and away from the lungs for- 
 eign particles which may be breathed in with 
 the air. But notwithstanding all these condi- 
 tions which serve to guard the exposed indi- 
 
THE STORY OF THE BACTERIA. 79 
 
 vidual against the disease-producing bacteria, 
 it still remains true that no man can acquire 
 tuberculosis without getting into his body this 
 particular bacillus from some infected individ- 
 ual or animal. 
 
 The Bacillus tuberculosis can be cultivated 
 artificially in the laboratory on potatoes or 
 other solid media, provided the surfaces are 
 kept always moist and the temperature kept 
 approximately at that of the human body. It 
 does not grow in nature outside of the human 
 or animal body, but it may remain alive for a 
 long time, even in the thoroughly dry condi- 
 tion, and ready to grow again when it gets into 
 the body under favorable conditions. 
 
 The conclusions which almost thrust them- 
 selves upon us from what we have thus learned 
 about tuberculosis are very plain. Tubercu- 
 lar cattle ought to be killed at once and 
 their carcases burned or otherwise rendered 
 innocuous just as soon as the disease is 
 discovered, and never allowed to get into the 
 markets. Pecuniary losses which individuals 
 might thus suffer are not worthy of a moment's 
 consideration as weighing against such obvi- 
 
8O THE STORY OF THE BACTERIA. 
 
 ously necessary preventive measures. These 
 ends ought to be secured first by a more rigid 
 inspection of cattle and of meat on the part of 
 authorized persons, and second by the enact- 
 ment of such laws as would secure for persons 
 who knowingly sell tuberculous meat or milk 
 for food such penalties as they would incur 
 from any other form of purposed or care- 
 less poisoning of their fellow-men. 
 
 It would be very difficult to stop by any sort 
 of legal enactment the spread of the tubercle 
 bacilli by means of the air from man to man. 
 But a thorough acquaintance of all persons 
 with the fact that a consumptive patient may 
 be a source of actual danger to all about him, 
 unless the proper precautions are adopted, 
 would do much to lessen the evil. 
 
 Steamship and railroad companies should be 
 obliged to furnish separate accommodations for 
 persons thus affected, so that no well person 
 should ever be forced in the exigencies of 
 travel to expose himself to the liability of 
 infection. 
 
 Such regulations and discriminations as are 
 here suggested would of course often be 
 
THE STORY OF THE BACTERIA. 8 1 
 
 extremely annoying to the victims of the 
 disease and their friends as well as to all 
 immediately concerned. But some such under- 
 standing must be come to, unless people are to 
 go on needlessly dying from this most im- 
 portant disease. 
 
 The best way of disposing of the sputum oi 
 consumptive persons, which, if allowed to dry, 
 may, as we have seen, become the source of 
 active danger to himself as well as to others, is 
 by burning. 
 
 It may be received into small cheap wooden 
 or pasteboard boxes, which are now made and 
 sold very cheaply by the druggists, and which 
 at frequent intervals, together with their con- 
 tents, should be burned in the stove, furnace, 
 or fireplace. When handkerchiefs or cloths 
 are used to receive the material coughed up, 
 these should be either burned as early as 
 possible, or soaked for several hours in a five per 
 cent, solution of carbolic acid and then boiled 
 and washed. But the use of handkerchiefs and 
 cloths is to be avoided for this purpose as 
 much as possible, because they afford most 
 favorable conditions for the drying and distribu- 
 tion of the infectious material. 
 
82 THE STORY OF THE BACTERIA. 
 
 But while we are thus led by the knowledge 
 which has been gained of the tubercle bacillus 
 to a more precise notion as to what should be 
 done to prevent the spread of the disease, 
 what has the accumulated lore to offer of hope 
 or comfort to those already stricken. In the 
 first place, the physician can now say positively 
 by finding the bacilli in the material discharged 
 from the lungs, in many cases even in very 
 early stages, that the lung is diseased : and we 
 now know that consumption is by no means a 
 hopeless disease, especially if it be detected in 
 its early stages. We know that the cells of the 
 body, if they are in a properly active and vig- 
 orous condition, have a tendency to destroy the 
 germs. And in a great many cases the wise 
 physician may, by recommending changes of 
 climate, improved conditions of hygiene, 
 proper exercise and food, as well as by the 
 giving of sustaining and strengthening medi- 
 cines, hold out to his patient a good hope of 
 ultimate recovery or of prolonged and com- 
 fortable life. 
 
 We battle to-day at any rate with a known 
 and comprehensible foe, and no longer grope 
 
THE STORY OF THE BACTERIA. 83 
 
 in the dark after a mysterious and unknown 
 enemy. The hope of the enlightened physi- 
 cian looks out towards a time when we may 
 have learned some direct and efficient means 
 of destroying the invading germs in the body, 
 but, in the meantime, by aiding the body's 
 inherent means of cure, he feels himself no 
 longer helpless, and is grateful for so much aid 
 as scientific research, as yet, has furnished him 
 in dealing with this dread disease. 
 
CHAPTER VIII. 
 
 BACTERIA AND TYPHOID FEVER. 
 
 TYPHOID fever is one of the serious and 
 common diseases, occurring among all 
 classes of people, which is definitely known to 
 be caused by bacteria. The germs causing 
 this disease are little rods or bacilli considera- 
 bly larger than those which cause tuberculosis. 
 
 There are several forms of low fever, and 
 some other diseases due to various causes, 
 which considerably resemble typhoid fever, and 
 are not infrequently mistaken for it. But genu- 
 ine typhoid fever is caused by this particular 
 germ, and no other, and is never caused in 
 any other way. 
 
 This typhoid bacillus is not known to grow 
 outside the body, to any considerable extent 
 at least, except when artificially cultivated by 
 the biologist for purposes of study. But it 
 may remain alive for a good while outside the 
 body in water or under other conditions. 
 
 84 
 
THE STORY OF THE BACTERIA. 85 
 
 The typhoid germ, in the large majority of 
 cases, attacks the body through the intestinal 
 canal. When it gets into the intestines, if in 
 sufficient quantity and the conditions are favor- 
 able, it multiplies, and enormous numbers 
 of the germs are thus produced. Some of 
 these gain access to certain of the other inter- 
 nal organs, but most of them either complete 
 their existence in the intestinal canal, or are 
 cast out in the living condition with the diar- 
 rhceal discharges which so constantly accom- 
 pany this disease. 
 
 It seems most probable, from what we know 
 at present about the action of the typhoid 
 bacilli in this disease, that, as they grow and 
 multiply in the bowels, they produce a soluble 
 poison ptomaine, which is absorbed, just as 
 some kinds of food might be, and carried to 
 various parts of the body, producing effects 
 which we recognize as symptoms of the disease. 
 The bacteria themselves remain, as it would 
 seem, for the most part, in the intestinal canal, 
 to pass off in the discharges. 
 
 The great and important source of infection 
 the means by which the disease is usually 
 
86 THE STORY OF THE BACTERIA. 
 
 spread is these discharges from the bowels, 
 containing the living, virulent typhoid bacilli. 
 
 Here, we have an essentially similar con- 
 dition of affairs to that in tuberculosis, namely, 
 bacteria of a particular species causing a dis- 
 ease which, without them, could not or does 
 not, so far as we know, exist, and after in- 
 ducing the disease in an individual, being 
 discharged alive and virulent from the body. 
 Here, as in tuberculosis, although the mode of 
 infection is somewhat different, if all the dis- 
 charges from persons suffering from the dis- 
 ease could be immediately destroyed by car- 
 bolic acid or corrosive sublimate, all danger of 
 infection, so far as we know, would be removed. 
 Typhoid fever is thus a preventable disease. 
 
 So far as we know, typhoid fever affects 
 man alone, and he alone forms the source of 
 infection. But, unfortunately, the bacteria are 
 not generally destroyed, and the house-mates 
 of the patient, or those who use the same water 
 supply, or are dependent upon the same food 
 sources, or subject to a connecting and defec- 
 tive sewage system, now and then are liable, 
 through food, or water, or air, to take into the 
 
THE STORY OF THE BACTERIA. 87 
 
 intestinal canal some of the tiny germs, not 
 larger than the motes in the sunbeam, but 
 bearing in them the seeds of disease, or even 
 death. 
 
 Altogether the probabilities are that in the 
 majority of cases the typhoid-fever germs are 
 most frequently carried and consumed in water 
 which has in some way been polluted by 
 human waste containing the typhoid germ. 
 
 It seems quite incredible, when put down in 
 black and white on paper, that responsible and 
 sane persons of ordinary intelligence, knowing 
 that typhoid fever is caused by a living germ, 
 knowing that this is thrown off from the body 
 in the living condition and without being 
 destroyed, is allowed to run through the 
 sewer pipes into the nearest stream or lake, 
 should for an instant consent to have the 
 water of this stream or lake taken from 
 within a short distance of the sewer opening, 
 and often in line of direct current, and 
 distributed in their houses unpurified, and 
 used upon their tables. And yet it would be 
 but the telling of old stories for the writer to 
 cite case after case in which this offence against 
 
88 THE STORY OF THE BACTERIA. 
 
 common decency, to say nothing of good 
 taste, is practised under conditions much more 
 flagrant than these. And then Providence or 
 Fate is shouldered with the responsibility 
 when the careless or ignorant persons them- 
 selves, or the innocent victims of their criminal 
 neglect, are stricken with typhoid fever. 
 
 There is little doubt that the typhoid-fever 
 bacilli sometimes enter houses from sewer 
 pipes containing them, owing to defective 
 traps or leaks in the pipes. Sewer gas is in 
 itself a very bad thing to have pouring into 
 houses, and is capable of inducing a great 
 variety of disturbances of health, some of 
 which are very serious indeed, but sewer gas 
 alone cannot induce typhoid fever. For that 
 the bacillus itself must be present. It is prob- 
 able that when the traps are allowed to get 
 dry, as no doubt often happens in shut-up city 
 houses during the summer, currents of sewer 
 gas sweeping up through the pipes, on whose 
 walls the typhoid bacilli have collected, may 
 dislodge these, if the sides of the pipes are 
 dry, and carry the germs as floating dust 
 into the rooms, where they may settle, and 
 
THE STORY OF THE BACTERIA. 89 
 
 finally, sooner or later, gain access to the food 
 or drink of the inmates. This mode of con- 
 veyance of the germ of typhoid fever has not 
 yet been proven, but, as a reasonable hypothe- 
 sis, is closely in accord with what we know but 
 too well of the outbreaks of typhoid fever 
 which so often occur on the return of house- 
 holds in the autumn to their city homes. 
 
 It has been abundantly proven by careful 
 experiments that the typhoid bacillus can re- 
 main alive for long periods when frozen solidly 
 in a block of ice. The disease-producing bac- 
 teria which may be conveyed in ice in impure 
 water to the body will be considered in a sub- 
 sequent chapter. 
 
CHAPTER IX. 
 
 THE RELATIONS OF BACTERIA TO ASIATIC 
 CHOLERA. 
 
 HISTORY records many tragic stones of 
 sudden outbreaks of fatal disease which 
 spreading like wildfire among the people have 
 brought untold miseries and countless deaths. 
 
 In early times these frightful whirlwinds of 
 disease were looked upon as penal visitations 
 of the Supreme Powers, and in the utter panic 
 which they so often induced little was done in 
 the way of studying their nature or staying 
 their progress. 
 
 Among the more important of these tragic 
 epidemics which have been experienced and 
 carefully observed since science has withdrawn 
 the veil of superstition from them, stands Asi- 
 atic cholera. 
 
 In some parts of the world this disease is 
 constantly present and claims each year a vary- 
 
 90 
 
THE STORY OF THE BACTERIA. 91 
 
 ing number of victims. But Europe and Amer- 
 ica are in general free from it, save that now 
 and then coming from its home in the far East 
 it sweeps along the seaboard or over the coun- 
 try, bringing in a greater or less degree the old- 
 time panic and misery and death in its train. 
 Occasionally it finds lodgment upon our own 
 shores and has penetrated into the interior. 
 
 Now up to within a few years we have not 
 known what the cause of this disease really 
 was. It seemed to be something which could be 
 brought in ships and wrapped up in clothing, 
 and was evidently communicable from man to 
 man. Such measures of stopping the spread 
 of the disease by isolating the sick, and such 
 general regulation of the diet and habits as 
 seemed from experience best adapted to pro- 
 tect the well, were formulated and practised. 
 But the utter lack of knowledge as to the exact 
 nature of the contagion frequently rendered 
 futile the one and uncertain the others. 
 
 To-day we know that Asiatic cholera is 
 caused by a little curved bacillus, which on 
 getting into the intestinal canal of human 
 beings multiplies with such rapidity that 
 
Q2 THE STORY OF THE BACTERIA. 
 
 within a few days or hours the body may 
 be overwhelmed with the poisonous material 
 which it eliminates as it grows. We know 
 that in certain stages of the disease the liv- 
 ing germs are discharged from the body in 
 vast numbers, and that if moisture be present 
 they may remain alive outside of the body for 
 long periods and may even multiply. They 
 can thus remain alive for some time in water 
 and on the moist surfaces of vegetables and 
 fruits and clothing. 
 
 There is no good reason for believing that 
 any other germ or organism than this particu- 
 lar curved bacillus ever induces Asiatic cholera, 
 or that the disease is ever caused by any thing 
 else. The only known way in which the infec- 
 tion is conveyed from man to man is by the 
 taking into the intestinal canal, either by water 
 or food or in some other way, some of the 
 cholera bacilli which have come directly or indi- 
 rectly from some human victim of the disease. 
 
 The germs may remain alive for a long time 
 if kept moist, and so the disease may be con- 
 veyed for long distances in bundles of infected 
 clothing. A few hours of thorough drying or 
 
THE STORY OF THE BACTERIA. 93 
 
 steaming-, or the application of suitable disin- 
 fectants, such as strong carbolic acid or corro- 
 sive sublimate, readily secures total destruction 
 of the life of the germs. 
 
 In Asiatic cholera, as in all of the other 
 bacterial diseases which we have thus far 
 studied, predisposition of the individual is an 
 important factor in the acquirement of the dis- 
 ease. This simply means that there are cer- 
 tain conditions of the body cells which render 
 them less able to resist the incursions of for- 
 eign organisms like the bacteria, or which fur- 
 nish conditions favorable to their growth and 
 
 o 
 
 proliferation. 
 
 We have seen that in tuberculosis this pre- 
 disposition to the disease, whatever its exact 
 nature is, may be in marked degree hereditary. 
 In Asiatic cholera a disordered condition of 
 the digestion appears to favor the occurrence 
 of an attack of the disease. In typhoid fever, 
 analogous predisposing factors seem to deter- 
 mine that when exposed to the same risk of 
 infection one individual may be attacked with 
 the disease and another not. But alike in all 
 these forms of bacterial disease the particular 
 
94 THE STORY OF THE BACTERIA. 
 
 species of bacteria belonging to each must be 
 present, predisposition or no predisposition, or 
 the disease cannot occur. 
 
 Typhoid fever and cholera are often called 
 filth diseases, and to bad food, foul air, sewer 
 gas, and overcrowding their occurrence has 
 often been attributed. This is in a sense true, 
 since these adverse conditions are apt to induce 
 a state of the body which renders it less resist- 
 ent than it should naturally be to various dele- 
 terious agencies ; but no imaginable degree of 
 unsanitary conditions could ever induce tuber- 
 culosis, or typhoid fever, or Asiatic cholera 
 without the presence of the particular germ 
 which causes each. None of these diseases 
 can spring up among any class or condition of 
 people without the introduction of the germ 
 from outside. 
 
 The recently acquired knowledge of the 
 cause of Asiatic cholera has thus far aided but 
 little in the treatment of persons already its 
 victims. On the other hand, knowing defi- 
 nitely, as we now do, what causes the disease, 
 how and under what conditions it spreads, and 
 what will destroy the germs, we are to-day in 
 
THE STORY OF THE BACTERTA. 95 
 
 a condition, wherever sanitary and proper 
 quarantine regulations are efficiently carried 
 out, to largely prevent the access of the dis- 
 ease to our country, to stay the progress of an 
 epidemic at its very outset, and to promptly 
 allay the panic which the advent of a mysteri- 
 ous and deadly scourge is so prone to incite 
 
CHAPTER X. 
 
 THE RELATION OF BACTERIA TO DIPHTHERIA, 
 PNEUMONIA, SCARLET-FEVER, ETC. 
 
 THERE are several diseases besides those 
 which we have considered in some de- 
 tail which are proven to be caused by the 
 entrance of bacteria into the body. There is 
 a still larger number which we believe, and 
 with the very best of reasons, to be caused by 
 bacteria, but from which the germs have not 
 yet been isolated and carefully studied so that 
 we can speak positively about them. 
 
 Diphtheria. 
 
 Diphtheria is one of the most dreaded of 
 the diseases, especially in childhood, which are 
 known to be caused by bacteria. We are not 
 yet quite certain whether it is always caused 
 by one form of germs, or whether in the differ- 
 ent outbreaks or in different regions sometimes 
 
 
 
1 UNIVERSITY ) 
 
 THE STORY OF THE ^S^Sit^^ 97 
 
 one and sometimes another species induces 
 the disease. 
 
 It has been shown that diphtheria, as it oc- 
 curs in children's asylums in New York, may 
 be caused by a streptococcus, which, when it 
 gets into the mucous membranes of the air 
 passages, especially if these are already in an 
 inflamed condition, can produce those local 
 changes which are so well known to accompany 
 this serious disease. 
 
 It has been furthermore shown that these 
 streptococci may remain alive for long periods, 
 when thoroughly dried, as in the dust, and it 
 has been found in the living and virulent con- 
 dition floating in the dust of the air of rooms 
 in which children suffering from diphtheria 
 were confined. It has been found in the 
 mouths of children who had been exposed to 
 the disease, and very soon after some of these 
 children suffered from serious and fatal attacks 
 of diphtheria. This bacterium has been shown 
 to be readily killed by moderately strong solu- 
 tions of carbolic acid and corrosive sublimate. 
 
 It is very well known that if the membranes 
 which are so apt to stop up the air passages in 
 
98 THE STORY OF THE BACTERIA. 
 
 diphtheria, when in the fresh condition, come 
 in contact with the mouths or air passages of 
 healthy persons, they may set up the disease. 
 This is because the material composing the 
 membranes may contain large numbers of the 
 living, virulent germs. It is furthermore known 
 that the poison of diphtheria may linger for long 
 periods in rooms where the disease has occurred, 
 and may be conveyed on the clothing of per- 
 sons who have come in contact with the sick. 
 
 Now in this, as in the other bacterial dis- 
 eases which we have studied, if all the material 
 which is cast off and discharged from the body 
 were at once received into strong disinfecting 
 solutions or burned, so that the germs might 
 be killed, the disease would have little tendency 
 to spread. But if, as is too often the case, the 
 discharged particles are allowed to collect on 
 handkerchiefs, or bedding, or clothing, or on 
 the floors, they dry and finally become ground 
 up and mingle with the dust, and as the germs 
 are not killed to any great extent by the dry- 
 ing, when the dust is inhaled it may, if the 
 individual be in a favorable condition for its 
 development, grow and induce the disease. 
 
THE STORY OF THE BACTERIA. 
 
 It is not unlikely that the dried diphtheria 
 germ may, from faulty plumbing or dry traps 
 in the pipes, be blown into rooms along with 
 the sewer gas, and that thus the disease is 
 sometimes communicated without direct con- 
 tact with an infected person. 
 
 Pneumonia. 
 
 Pneumonia, in its more common phases, is 
 another of the diseases which we believe to 
 be caused by bacteria. The germ which pro- 
 duces the trouble has been many times sepa- 
 rated and carefully studied. It is called the 
 Pneumococcus. 
 
 So frequently does this disease follow ex- 
 posure to cold or wet, and so often does it 
 begin with symptoms which resemble those of 
 an ordinary cold, that it was long believed to 
 be, and still is popularly regarded, as usually 
 caused by these exposures. But most of those 
 who have carefully studied the disease by the 
 use of the modern scientific methods of re- 
 search are disposed to believe that the expos- 
 ure to cold and wet and other less well-defined 
 conditions which were formerly regarded as 
 
100 THE STORY Of THE BACTERIA. 
 
 actual causes, while exceedingly important, are 
 yet simply predisposing factors. They believe 
 that the reason why pneumonia is so frequently 
 associated with these conditions is that they 
 in some way fit the lungs to be a good grow- 
 ing place for the germs if at the favorable 
 moment they gain access to them through the 
 mouth. 
 
 We do not know much about the bacteria 
 which thus appear to cause pneumonia, so far 
 as their lurking places outside of the body are 
 concerned. But they are not infrequently 
 found in the mouths of healthy persons, and 
 are most likely distributed through the air with 
 the dust. 
 
 The pneumonia which so frequently comes 
 on as a serious complication of diphtheria has 
 been shown to be caused by the germs which 
 cause the diphtheria itself getting down into 
 the lungs and producing their poisonous effects 
 there. 
 
 Scarlet-Fever, Measles, Yellow-Fever, etc. 
 There is a great deal in the nature and mode 
 of communication of scarlet-fever, measles, 
 
THE STORY OF THE BACTERIA. IOI 
 
 whooping-cough, and small-pox which indicates 
 that they too are bacterial diseases ; but the 
 specific organisms causing them have not yet 
 been identified. So that in attempting to 
 guard against their spread we are at present 
 obliged to make what use we can of the facts 
 which we know about the proven bacterial 
 diseases and the experience which has been 
 accumulated by physicians who so long and 
 faithfully have studied them at the bedside. 
 Against small-pox, however, we have a most 
 efficient safeguard in vaccination, although we 
 do not yet know the reason for the marvellous 
 protective effects of the procedure. 
 
 Yellow-Fever. 
 
 Yellow-fever is a disease of the utmost im- 
 portance in some parts of our country, about 
 the cause of which we are almost entirely in 
 the dark. Our knowledge of it is largely con- 
 fined to the characters of the disease as it is 
 seen at the bedside, and to the general con- 
 ditions under which it is liable to occur and 
 spread. In many respects it resembles the 
 known bacterial diseases, in others it differs 
 
102 THE STORY OF THE BACTERIA. 
 
 considerably from them. The attempts which 
 have thus far been made to find bacteria to 
 which it seems likely that it may owe its origin 
 have not been successful, although several 
 claims in this direction have been widely pub- 
 lished. 
 
 Malaria. 
 
 Malaria, in its protean phases, has been 
 thought by many to be caused by bacteria, but 
 the reliable observations thus far made do not 
 appear to support this view. There are pecul- 
 iar minute organisms very constantly found 
 in the blood in certain stages of malarial 
 poisoning which may ultimately prove to be 
 the cause of the attacks. But as this is not 
 yet definitely settled, and as at any rate the 
 suspected organisms are not bacteria, but be- 
 long in that lowly group of animals called 
 protozoa, we need not consider them further 
 here. 
 
CHAPTER XL 
 
 IMPURE FOOD AND AIR AS SOURCES OF BAC- 
 TERIAL INFECTION. 
 
 AS we glance back over the ground which 
 we have traversed together, we see that 
 the most common bacterial diseases which in 
 this country we are apt to come in contact 
 with, so far as they are definitely known to us, 
 are tuberculosis, typhoid fever, diphtheria, 
 pneumonia, and the wound diseases or blood 
 poisoning. 
 
 We have seen that in most of these diseases 
 the poison is liable to spread from one indi- 
 vidual to another, because it is not destroyed 
 by disinfectants, or in some other way, as soon 
 as possible after it is discharged from the dis- 
 eased person. 
 
 We have seen that the most common ways 
 in which the virulent bacteria are spread are 
 by the air we breathe, the food we eat, and 
 
 103 
 
104 THE STORY OF THE BACTERIA. 
 
 the water we drink. If any of these necessi- 
 ties of life contain in them the living germs of 
 these diseases, there is a liability of the infec- 
 tion of healthy or predisposed individuals. 
 
 The liability to acquire these diseases is 
 always increased in direct proportion to the 
 crowding together of the sick and the well 
 under unsanitary conditions in large communi- 
 ties. This is not because filth and dirt are in 
 themselves infectious, but because pathogenic 
 bacteria are liable to become mingled with the 
 rest. In other words, there is a simply filthy 
 filth, and there is a pathogenic filth, and the two 
 are very apt to go together. 
 
 No gas, however foul, no accumulation of 
 dirt, no degree of malnutrition or misery or 
 overcrowding can induce an infectious disease. 
 It is always and everywhere some particular 
 form of disease-producing germ which causes 
 the trouble. The other influences bear largely 
 upon the chances of incurring the disease, and 
 often determine the severity of its course or 
 its fatal ending, but they alone cannot cause it. 
 
 In considering what ought to be and what 
 can be done to prevent the spread of the bac- 
 
THE STORY OF THE BACTERIA. 1 05 
 
 terial diseases, it is evident at once that there 
 are two distinct classes of preventive measures : 
 first, those which must be arranged and en- 
 forced by the public authorities, such as 
 Health Boards and their officers ; and second, 
 those which depend upon the intelligence, 
 knowledge, and faithfulness of private indi- 
 viduals. It does not lie within the scope of 
 this little book to consider, except incidentally, 
 the measures which should be taken by the 
 authorities on the large scale, to ward off epi- 
 demics or to secure proper sanitary conditions 
 among the people. 
 
 It is not, in fact, the great and sweeping 
 epidemics, dramatic and frightful as they are, 
 which carry off prematurely the largest num- 
 ber of people ; but it is the bacterial diseases 
 which we have constantly with us, and to which 
 we have become so accustomed that we do 
 not usually realize their vast importance, and 
 against which systematic and persistent cru- 
 sades on the part of the health authorities are 
 only occasionally and fitfully undertaken. 
 Among the bacterial diseases which are well 
 understood, the most important, in some re- 
 
106 THE STORY OF THE BACTERIA. 
 
 spects, in this country are tuberculosis, typhoid 
 fever, and diphtheria. 
 
 The danger of infection with disease-pro- 
 ducing bacteria which we may encounter in 
 the ordinary paths of life lurk, as we have 
 seen, for the most part, either in food, or air, 
 or water. Let us now look at these sources 
 of danger a little more closely. 
 
 Impure Food as a Source of Bacterial Infection. 
 
 We have seen that the meat of tubercular 
 cattle and the milk of tubercular cows, and 
 the same is true of tubercular fowls, may con- 
 tain the living tubercle bacilli, and that if the 
 meat be not thoroughly cooked and the 
 milk not thoroughly boiled, these germs may 
 get into the intestinal canal, and cause dis- 
 ease. The remedy here lies in part in the 
 hands of the health officers, or, when their 
 efforts fail, in the hands of the consumer him- 
 self. A much more rigid inspection of cattle, 
 with full authority to destroy all infected herds, 
 should be at once established. It should be 
 thoroughly understood by every householder, 
 that if this be not done, uncooked meat, of 
 
THE STORY OF THE BACTERIA. ID? 
 
 whatever kind, should be altogether avoided ; 
 and the same should apply to milk. The boil- 
 ing of milk for from three quarters of an hour 
 to an hour suffices to kill the germs of tuber- 
 culosis. 
 
 Scarlet-fever and diphtheria may also, as 
 has been abundantly proven, be transmitted 
 by milk which has in any way been exposed 
 to the infection ; and hence the thorough 
 boiling of milk, in cities where the source of 
 the supply is not definitely known, would be a 
 wise precautionary measure. 
 
 Milk is such an excellent food medium for 
 the greatest variety of bacteria of nearly all 
 species, that although bacteria-free when it 
 comes from the cow, it may, before it reaches 
 the consumer, contain several millions of liv- 
 ing germs to one teaspoonful. Now it has 
 been found that milk which contains a great 
 many bacteria, although these may not be of 
 a kind which ordinarily produce any well de- 
 fined disease, may in young children produce 
 digestive disturbances and diarrhoea, which is 
 often of a very serious character. Milk from 
 the ordinary unknown sources of supply ought 
 
108 THE STORY OF THE BACTERIA. 
 
 therefore to be thoroughly boiled before it is 
 fed to infants and young children, and very 
 simple and inexpensive forms of apparatus for 
 this purpose have been devised and can be 
 recommended by any well informed physician. 
 
 As the germs of various diseases may be 
 floating in the air, especially in densely popu- 
 lated regions, all fruits, vegetables, and salads 
 ought to be thoroughly washed before they 
 are eaten, unless they are to be cooked. The 
 exposure of such articles of food on the side- 
 walks in cities, as is so often done, is a most 
 reprehensible practice, and this alone should 
 be enough to decide the householder to dis- 
 pense with the supplies of any dealer who per- 
 sists in it. 
 
 There is no doubt that the germs of typhoid 
 fever, and, when it is prevalent, those of Asiatic 
 cholera, are conveyed from one to another by 
 means of food on which in some way the 
 germs from the discharges of sick persons 
 have lodged. This is of course most apt to 
 occur among the poorer classes in large towns 
 whose market-stalls are the gutters, and whose 
 living-rooms, alike for sick and well, may 
 
THE STORY OF THE BACTERIA. 1 09 
 
 serve at once as kitchen, dining-room, garbage 
 reservoirs, and bedchambers. But among 
 those more fortunately circumstanced, the con- 
 veyance of the diphtheria, and probably of 
 typhoid-fever germs, on uncleansed spoons, 
 dishes, etc., is of no infrequent occurrence. 
 
 The Air as a Source of Bacterial Infection. 
 
 We have seen that the only way the air 
 which we breathe can be actually infectious, that 
 is, can be the means of transmitting a bacte- 
 rial disease, is, under ordinary conditions, by 
 carrying as dust the dried but living disease- 
 producing germs from some infected individual 
 or animal along with other and less harmful 
 dust. Thus it is that our recently acquired 
 knowledge of bacteria and other minute or- 
 
 o 
 
 ganisms has brought a new significance into 
 the problems of ventilation. Foul air we still 
 know to be bad and capable of inducing seri- 
 ous forms of disease, but the specific and most 
 significant elements of positive danger reside 
 in the floating dust. 
 
 The possibility of taking the bacteria of 
 tuberculosis and diphtheria into the mouth 
 
110 THE STORY OF TffE BACTERIA. 
 
 and lungs with the air out-of-doors, especially in 
 large cities, is, as we have already seen, imminent 
 and widespread, but ordinarily the dilution of 
 the dangerous elements is so great as to reduce 
 greatly the chances of evil effects from swal- 
 lowing or inhaling them. But still, in large 
 towns, whose streets are not faithfully cared 
 for, the probability of being obliged to pass 
 through clouds of dust whenever one goes 
 upon the streets, especially in the windy sea- 
 sons, is very unpleasantly suggestive of dan- 
 ger, and more than suggestive of filth. 
 
 In New York, even in districts where the 
 streets are measurably frequently attended to, 
 the insufficient watering of the pavements be- 
 fore the street-sweepers pass, the long periods 
 which often elapse before the dirt heaps are 
 carted off, and the reckless way in which the 
 dirt is shovelled into the carts, are all evi- 
 dences of carelessness which greatly increases 
 the risk of street infection, and abuses which 
 ought to be at once corrected. 
 
 But, after all, it is in living-rooms and in 
 places of assembly that we must look for the 
 most frequent sources of danger. While, as 
 
THE STORY OF THE BACTERIA. Ill 
 
 we have seen above, there is a certain heredi- 
 tary predisposition to tuberculosis which is 
 resident in the body cells themselves and of 
 the exact nature of which we are quite igno- 
 rant, there is little doubt that one of the most 
 important reasons why tuberculosis is apt to 
 run in families is that children and relatives of 
 consumptives are more liable than others to 
 come in direct contact with the disease-pro- 
 ducing germs, which have been thrown off 
 from the bodies of their house-mates under 
 conditions which permit of their drying and 
 inhalation as dust. 
 
 Theatres and churches, especially the 
 former, are apt, as is well known, to be alto- 
 gether inadequately ventilated. The headache 
 and malaise which are so prone to follow a 
 visit to many of our theatres, are evidences of 
 the bad air which we are usually forced to 
 breathe there ; but the more subtle dangers 
 here, as elsewhere, lurk in the dust which 
 equally with the bad air is forced upon us. 
 
 No adequate means exist in most theatres 
 for ridding the air of the dust. The best of 
 them indeed are swept and " dusted " system- 
 
112 THE STORY OF THE BACTERIA. 
 
 atically and the larger particles of dirt collected 
 and removed ; but the floating dust is simply 
 stirred up, and after settling is stirred up again 
 by the so called duster, and so partially 
 removed from the seats, but it settles again 
 on the floors, to be again set in motion by the 
 entering and retiring audience. It would be 
 safe to say that the only systematic mode of 
 removal of the floating dust from many of our 
 popular theatres and churches is by its lodg- 
 ment in the throats and lungs or on the 
 clothing of the people who visit them. 
 
 Some of the newer theatres are furnished 
 with improved and sufficient ventilating appa- 
 ratus, but some of them are not, and while we 
 admire the chaste gilding and sumptuous up- 
 holstery of the interior, and complacently 
 reflect that at length the law has forced 
 builders of places of amusement to afford a 
 measurable degree of security against being 
 burned alive, that element of danger in large 
 assemblies, more important and more subtle 
 than all the rest put together, namely, inade- 
 quate ventilation, is rarely commented upon or 
 thought about. There ought to be definite 
 
THE STORY OF THE BACTERIA. 113 
 
 regulations for all public assembly-rooms, 
 which should insure the forcing of a proper 
 amount of fresh air through them, which would 
 not only carry off foul air, but much of the 
 floating and possibly infectious dust with it. 
 
 In dwelling-houses, the problem of ventila- 
 tion is in many respects simpler than in large 
 assembly-rooms, because to a certain extent the 
 householder is aware of the possibilities of 
 dust infection, from the condition of health of 
 the inmates, and can act accordingly. But 
 even here, under ordinary conditions, there 
 seems to be, from what we have learned about 
 the bacteria, more reasons than we have 
 before appreciated for securing adequate ven- 
 tilation such ventilation as shall carry off not 
 only the used-up air but the floating dust. 
 
 The ordinary practice of occasionally stirring 
 up the settled dust with a feather-duster should 
 give place to the use of moist cloths or dry 
 cloths frequently shaken out-of-doors, so that 
 the dust may be removed and not simply 
 redistributed. This becomes the more impor- 
 tant if any inmate of the house is suffering 
 from one of the bacterial diseases. 
 
114 THE STORY OF THE BACTERIA. 
 
 In the interests of health the fitting of houses 
 with simpler furniture or less heavy hangings 
 and fixed carpets is greatly to be desired. 
 
 The regulation of the sick-room, and its 
 communication with the rest of the house, is a 
 matter on which the advice of the physician 
 should be sought. First and foremost should 
 stand the systematic and careful destruction of 
 the infectious material in all discharges of what- 
 ever sort from diseased persons, by burning or 
 by the proper disinfecting solutions such as five 
 per cent, carbolic acid. In this solution the dis- 
 charges should be allowed to soak for several 
 hours before they are thrown into the sewer or 
 otherwise disposed of. As to the cleansing o{ 
 rooms after their occupancy by persons who 
 have suffered from bacterial diseases, direc- 
 tions should be obtained from the physician or 
 from the health authorities. 
 
 The danger of infection with the germ of 
 tuberculosis through the air is very widespread, 
 because consumptive persons are often for long 
 periods not confined to their houses, or rooms, 
 or beds, but may be more or less active centres 
 of infection by mingling with the well in all the 
 
THE STORY OF THE BACTERIA. 
 
 ordinary walks of life. We have seen already 
 by what comparatively simple means a large 
 part of the danger of the spread of tuberculosis 
 and diphtheria might be prevented. The risk 
 of dust infection from diphtheria, and probably 
 from other somewhat similar diseases, such as 
 measles and scarlet-fever, is more apt to be 
 limited to rooms or houses where the disease 
 has occurred, because the victims of these dis- 
 eases are usually sick enough to be confined to 
 the house or bed. But there are, as all physi- 
 cians know, frequently enough cases of these 
 diseases in which the patients go about among 
 their fellows throughout the whole course of 
 
 o 
 
 the illness, or at least for some time after it is 
 fully established. 
 
 The possibility of dust infection with any 
 of the diseases which we have been consider- 
 ing, emphasizes the importance of breathing 
 through the nose and keeping the mouth shut 
 except when it is necessary to have it open. 
 
CHAPTER XII. 
 
 IMPURE WATER AND ICE AS A SOURCE OF 
 BACTERIAL DISEASE. 
 
 Impure Water. 
 
 WE have seen in another part of this 
 book that natural surface waters always 
 contain considerable numbers of living bacteria 
 of various kinds, which are growing and pro- 
 liferating there, and no doubt actually purify- 
 ing the water in a certain way by feeding upon 
 and removing from it organic material which 
 has collected or been dissolved. Now these 
 bacteria in moderate numbers, under ordinary 
 conditions, are not at all harmful to the con- 
 sumer of the water for drinking or culinary 
 purposes. 
 
 But, on the other hand, if the water 
 becomes stagnant and the ordinarily harm- 
 less bacteria collect in very large numbers, it 
 has been abundantly shown by most bitter 
 
 116 
 
THE STORY OF THE BACTERIA. 
 
 experience that the use of the water may give 
 rise to serious or even fatal acute disorders of 
 the digestive system. Cholera morbus and 
 the so-called winter cholera are apparently 
 sometimes caused in this way. Young chil- 
 dren are especially susceptible to the bad 
 influences of such water, and the boiling of it, 
 or the change of supply, has repeatedly been 
 found sufficient to stop attacks of cholera in- 
 fantum or the summer diarrhoea of young 
 children. 
 
 On the whole, however, the bacteria which 
 water naturally contains as it is found in lakes, 
 running streams, and good springs are quite 
 harmless, unless they are allowed by stagna- 
 tion to accumulate to a very considerable 
 degree. We do not yet definitely know to 
 what extent the ordinary harmless bacteria 
 might be allowed to accumulate in drinking- 
 water before it would become harmful. But 
 the limit is usually somewhat arbitrarily placed 
 at present at from three hundred to five hun- 
 dred to the teaspoonful. 
 
 The frequent real and serious dangers from 
 impure drinking-water do not lie in the bacte- 
 
118 THE STORY OF THE BACTERIA. 
 
 ria which naturally occur there at all, but in 
 those which get into it from outside, through 
 pollution by the waste from animals and 
 human beings, and especially from human 
 beings who are the victims of some bacterial 
 disease. 
 
 Polluted water may convey the bacteria 
 which cause Asiatic cholera, and the same is 
 true for diphtheria or the wound diseases, 
 and doubtless many others, but the spread of 
 these latter diseases in this way is no doubt 
 quite infrequent. 
 
 It is typhoid fever, whose germs, of all 
 those which cause disease, are, so far as 
 we now know, most apt to be spread by pol- 
 luted water. The discharges from persons ill 
 of typhoid fever, thrown without disinfection 
 into the vaults of country or village out-houses, 
 which, in an appalling number of cases, are 
 in direct communication, through underground 
 channels, with the wells, or with springs from 
 which the farmer supplies the family or guests, 
 may pass, with but a very moderate dilution, 
 into the digestive tracts of the unsuspecting 
 victim. It is ignorance, not Providence, which, 
 
THE STORY OF THE BACTERIA. I IQ 
 
 under these conditions, determines an epidemic 
 of typhoid fever. 
 
 The water supplies of large towns come, for 
 the most part, either from large rivers, or lakes, 
 or artificial reservoirs along the course of 
 smaller streams, or from artificial wells, which, 
 piercing the upper strata, gain access to the 
 deep underlying collections. Now in the sur- 
 face water supplies, as from rivers or from 
 lakes, man is his own worst enemy, because 
 the most serious dangers from impure waters 
 arise from its contamination with human waste. 
 
 Many great water supplies, which, under 
 ordinary conditions are good, are constantly 
 liable to become sources of danger, because 
 the sewage from dwellings is discharged, if 
 not into them, still, so near to them that it 
 may now and then enter, being washed in by 
 rains or in some other way. This, under 
 ordinary conditions, may, if the sewage be 
 largely diluted in the reservoirs or streams, be 
 simply disgusting and filthy, though not posi- 
 tively dangerous. But if, as is at any time 
 liable to happen, typhoid-fever discharges get 
 into the waste-pipes and so into the water, the 
 
120 THE STORY OF THE BACTERIA. 
 
 danger of the spread of this disease becomes 
 of great importance. 
 
 The great water supply of the city of New 
 York, the Croton, is of this character. The 
 water comes from a large territory known as 
 the Croton water-shed, and is naturally a very 
 good water supply indeed ; but along the 
 streams and reservoirs which collect the water 
 are numerous villages and scattered dwelling- 
 houses. While some attempt is made to keep 
 the banks of the water-ways free from sources 
 of sewage and waste contamination, as they 
 are largely private property this is not ade- 
 quately done, and at any time an epidemic of 
 typhoid fever in houses or villages along the 
 Croton streams and lakes would be liable to 
 cause a dangerous contamination of our city 
 supply. 
 
 There are two ways in which this positive 
 danger can be obviated. One is by the pur- 
 chase, by the State, of a strip of land along all 
 the shores of the Croton water system, and 
 the removal to a safe distance of all possible 
 sources of contamination. 
 
 Another means of security, which, perhaps, 
 
THE STORY OF THE BACTERIA. 121 
 
 in the lono- run would be the most efficient 
 
 o 
 
 and most thoroughly under control of the 
 authorities, would be the construction of large 
 filter-beds, or filtering apparatus, by means of 
 which the water might be freed from all dan- 
 gerous contaminations under all conditions. It 
 will thus be seen that while the Croton water 
 is not at present a source of actual danger it 
 may at any moment become so, unless some 
 efficient means be taken to protect its sources, 
 or purify it before distribution. 
 
 Conditions similar to that of the Croton are 
 very common in the city water supplies every- 
 where, in this, as in other countries. And the 
 more rapidly are the regions from which the 
 water is derived becoming populated, the more 
 serious does the danger grow. 
 
 Another great source of water supply for 
 large cities and towns is the rivers on whose 
 banks they are built. The water is usually 
 taken at a point some distance above the 
 town, so as to avoid the sewage of the town 
 itself, which, as a rule, is allowed to escape 
 directly into it. But in almost all cases, in 
 thickly settled countries, there are other towns 
 
122 THE STORY OF THE BACTERIA. 
 
 on these streams above the points at which the 
 water is taken, polluting it with their sewage. 
 Now so prevalent is typhoid fever all over the 
 civilized world that the sewage of every large 
 town is liable to contain greater or less numbers 
 of living typhoid bacilli. 
 
 The city of Albany, N. Y., which takes its 
 drinking-water from the Hudson River a 
 short distance above the town, just after it 
 has received the sewage of Troy and that of 
 several smaller towns on the banks of both the 
 Hudson and the Mohawk above, is an example 
 of a city which relies upon a water supply 
 always both filthy and dangerous. 
 
 Philadelphia is another great city whose 
 water supply from the Schuylkill River is of 
 the most dangerous and disgusting character, 
 from its large admixture of sewage and human 
 waste. The typhoid-fever statistics of Phila- 
 delphia are abundant witnesses to the almost 
 incredible apathy or carelessness of its authori- 
 ties. 
 
 In older countries where the sanitary dan- 
 gers which always grow with the increase and 
 massing together of the people have been 
 
THE STORY OF THE BACTERIA. 12$ 
 
 longer observed and more definitely recog- 
 nized than in our own, legal enactments have 
 been long in force to prevent the pollution of 
 streams which might be sources of water sup- 
 ply of towns. But still large cities like Lon- 
 don and Berlin have found it necessary to 
 further protect themselves against disease-pro- 
 ducing organisms and against filth, by the 
 maintenance of filtering systems on the large 
 scale, by which the dangerous elements of a 
 contaminated water may be largely or en- 
 tirely removed. 
 
 We should not forget that contaminated 
 water always tends to purify itself in certain 
 ways when exposed to the air in large volumes, 
 as in lakes or running streams. Nor should 
 we lose sight of the fact that a moderate 
 amount of sewage, when poured into a large 
 volume of water, becomes so considerably 
 diluted, that its dangerous elements are much 
 less numerous in any given glass or volume 
 of water than in sewage itself. But such con- 
 siderations can afford but little real consola- 
 tion to those who find themselves forced to 
 drink sewage, even though it be very largely 
 
124 THE STORY OF THE BACTERIA. 
 
 diluted. The sewage may contain one hun- 
 dred thousand typhoid germs to one teacupful, 
 while the diluted mixture has in it not more 
 than one to the same volume. But it should 
 never be forgotten that the one germ is capa- 
 ble of multiplying in the human body to an 
 enormous extent, and for this reason, in the 
 living bacterial poison dilution is of much less 
 significance than in ordinary poisons which are 
 not alive and self-propagating. 
 
 The fact is, that in view of all that we have 
 seen of the nature of bacteria and their dis- 
 ease-producing powers, sewage-polluted water 
 from wells, or springs, or rivers, or lakes, ought 
 not to be used for drinking and culinary pur- 
 poses without some system of purification 
 which is demonstrably efficient. 
 
 The new methods of bacterial analysis of 
 water, which have been described in the earlier 
 pages of this book, now enable us to tell with 
 a great deal of certainty, sometimes with and 
 sometimes without a chemical analysis, whether 
 or not a given water has actually been polluted 
 with sewage, or human or animal waste, and 
 whether the modes of purification to which it 
 
THE STORY OF THE BACTERIA. 12$ 
 
 has been subjected, either naturally or artifi- 
 cially, have actually been efficacious in remov- 
 ing the living germs. 
 
 It is thus evident that upon the intelligence, 
 knowledge, and fidelity, of the authorities 
 largely rests the responsibility of pure water 
 supplies for cities and towns, and the house- 
 holder is to a large degree at the mercy of 
 these officials, so far as his protection against 
 the acquirement of bacterial disease, especially 
 typhoid fever, is concerned. For it has been 
 shown over and over again, by the most care- 
 ful and elaborate experiments and examina- 
 tions, that the small so-called faucet filters, and 
 pretty much all the reservoir domestic filters, 
 do not separate the bacteria from contami- 
 nated water in a reliable way. The water is 
 often strained by them and so freed from its 
 coarser floating particles, and then may appear 
 quite clear and limpid, and some of the bac- 
 teria may be at first removed ; but after a 
 little while not only do these small filters let 
 the invisible bacteria through their pores in 
 large numbers, but they may actually afford 
 breeding- and lurking-places for the living 
 
126 THE STORY OF THE BACTERIA. 
 
 germs, the disease-producing forms among 
 the rest. 
 
 Filtration on the large scale in properly 
 arranged systems appears to be the only reli- 
 able way of freeing contaminated water 
 mechanically from its bacterial ingredients. 
 
 Thorough boiling of water for at least an 
 hour will, however, kill the bacteria, and to 
 this, in the last resort, the householder must 
 have recourse when the water supply is justly 
 suspected to be causing and fostering disease. 
 This purification of water by boiling may be 
 done by the householder himself, or, if he can 
 afford it, he may supply himself with the dis- 
 tilled and aerated water which is now furnished 
 in many towns. 
 
 But, after all, when the facts about the dan- 
 gers of a polluted water supply become gener- 
 ally known, it ought not to be necessary for 
 the householder to adopt any domestic pre- 
 cautions against water infection in towns or 
 cities. If politics, or private or corporate 
 greed, or general ignorance or apathy stand 
 in the way of sanitary reform, the outlook for 
 the water consumer is indeed not encouraging, 
 
THE STORY OF THE BACTERIA. 1 27 
 
 but even these obstacles in the way of com- 
 fortable existence have been and may again be 
 set aside. 
 
 Those who dwell in the country, and those 
 who repair thither in the summer, should be 
 very watchful of the water which comes from 
 the ordinary wells. It is quite true that the 
 water which soaks into the majority of wells 
 in the country and in villages has been filtered, 
 and more or less purified, as it passed through 
 the soil and earth about the well. But in a 
 great many cases the surface water runs direct- 
 ly into the well at the top. Washing is not 
 infrequently done in the immediate vicinity of 
 the well, and the waste and dirty water runs 
 directly, or with but little filtration, back into 
 the common receptacle. The vaults of out- 
 houses, barn-yards, and pigstyes are often in 
 close proximity to the well, on establishments 
 which in circulars and newspapers figure as 
 country health resorts. And this is by no means 
 true alone of those which are inexpensive and 
 primitive, but almost equally so of many of 
 the more fashionable and popular resorts. 
 
 Every person who goes or sends his family 
 
128 THE STORY OF THE BACTERIA. 
 
 into the country in the summer, should per- 
 sonally inspect the drinking-water supply and 
 assure himself that it is good. This is actually 
 of far greater importance than the size of the 
 rooms, the price of board, or the diversity of 
 amusements, or any other of the score of 
 things about which one so scrupulously in- 
 quires before laying out the summer cam- 
 paign. 
 
 Wells ought to be cemented water-tight for 
 from eight to twelve feet below the surface. 
 They should rise several inches above the level 
 of the surface of the ground, which should be 
 cemented and made to slope away in all direc- 
 tions from the opening, so that all drippings 
 and surface water may be carried off to a dis- 
 tance of several feet before it soaks into the 
 ground. 
 
 It should always be borne in mind that the 
 water of ordinary wells is simply surface water, 
 which has filtered down through the soil, and 
 collected in the reservoir which the well ex- 
 cavation makes, and that in closely populated 
 regions the soil, which originally may have 
 been efficient as a filter, may finally become so 
 
THE STORY OF THE BACTERIA. I2Q 
 
 filthy as not only no longer to cleanse the 
 water, but to actually infect or contaminate it 
 as it percolates through. 
 
 It is difficult to lay down rules by which the 
 safety of country and village wells may be 
 judged. But a very moderate acquaintance 
 with sanitary principles will usually guide one 
 to a just opinion. The argument which the 
 enquirer is most apt to encounter favoring the 
 salubrity of a country or village well, is that 
 the owners' fathers and grandfathers drank 
 water from the well all their lives, and they 
 and their families lived to a good old age. 
 But the fact is frequently lost sight of that the 
 slops and sewage of this long-lived race have 
 usually been accumulating in the soil about 
 the house, as the years have sped, and as their 
 towns and villages have grown the stables and 
 hog-pens have neared the ancestral roof-tree. 
 In short, that the sanitary conditions have en- 
 tirely changed. The fact is, that wells, as they 
 exist in most villages, and on many farms in 
 this country, are an abomination and a per- 
 petual menace to the health and lives of those 
 who use them. 
 
130 THE STORY OF THE BACTERIA. 
 
 Impure Ice. 
 
 The use of ice in preserving food and for 
 drinking purposes has become a very impor- 
 tant factor in modern life, and a means of 
 incalculable benefit to all classes of people. 
 
 It was formerly believed that freezing de- 
 stroyed in large measure the impurities of 
 water, and within certain limits this is true. 
 But it has been found, as the result of a long 
 series of careful experiments by numerous in- 
 vestigators, that those important contaminating 
 elements in polluted water, the bacteria, may 
 resist for long periods the influences of cold. 
 Good ice is so clear and beautiful that it is 
 difficult to believe that it may harbor among 
 its crystals larg-e numbers of even such tiny 
 bodies as the bacteria, but this is nevertheless 
 quite true. 
 
 It has been found that the ice which is 
 delivered in New York and in many other 
 large cities actually contains large numbers of 
 bacteria. 
 
 It has been further found that that most 
 dreaded form of bacteria, the typhoid bacillus, 
 may remain for long periods living and viru- 
 lent in solid ice blocks. 
 
THE STORY OF THE BACTERIA. 131 
 
 It follows directly from these simple but 
 undeniable facts that the sources of our ice 
 supply should be as carefully scrutinized in the 
 interests of the public health, as should the 
 sources of the water. But, unfortunately, under 
 the influence of the old idea that water was 
 thoroughly purified by freezing, it has become 
 the general practice of many of the dealers to 
 get their ice from almost any source, however 
 unclean, which is near or accessible enough to 
 the market to afford a profit. 
 
 One of the most flagrant examples of this 
 bad practice is seen in the ice supply of New 
 York City, which is in large part drawn from 
 the sewage-polluted Hudson, and in many 
 cases from the immediate vicinity of the sewer 
 openings. Some of the ice which is supplied 
 to New York is cut on moderately clean ponds 
 or lakes, but the consumer is almost never 
 certain that he is not getting Hudson-River 
 sewer-ice, even when he may fancy he has a 
 cleaner supply. 
 
 The fact is, ice should not be cut, at least 
 when it is to be used for drinking purposes, 
 from any source which would not be good if 
 used for drinking unfrozen. This is certainly 
 
132 THE STORY OF THE BACTERIA, 
 
 not the case with any of the Hudson-River 
 ice, nor with much of that which comes from 
 other sources. 
 
 The criterion of wholesome ice is of course 
 the same for all regions of the country. The 
 condition of affairs in New York is cited simply 
 because it is an example of the extremely ob- 
 jectionable and dangerous practices which 
 sensitive and refined people will indulge in 
 from force of habit or from ignorance of the 
 nature of their errors. 
 
 Many persons who are alive to the dirty and 
 dangerous character of much of the New-York 
 ice are looking eagerly either for a reform on 
 the part of the ice dealers in the character of 
 the places on which they cut their ice, or to 
 the establishment of manufactories of artificial 
 ice, which can be made from water purified by 
 distillation. It seems at present, however, as 
 if a spontaneous reform on the part of the ice 
 harvesters were not to be looked for, and that 
 this must be brought about either by legisla- 
 tive enactments or by a determined movement 
 on the part of a large number of consumers. 
 
 The dumping of city garbage in vacant lots 
 
THE STORY OF THE BACTERIA. 133 
 
 or in the water in the vicinity of towns is one 
 of those barbaric practices which strangely 
 enough still widely prevails in spite of the fact 
 that both efficient and cheap apparatus for 
 burning it are well known and employed by 
 many of the more intelligent and cleanly com- 
 munities. Thus the soil and the shores of 
 streams and other bodies of water near towns 
 are often polluted. 
 
 If sewage were everywhere systematically 
 destroyed, instead of being permitted to run 
 into and pollute the streams and lakes, which, 
 from their size and situation, afford the natural 
 water and ice supplies to towns in their vicin- 
 ity, the problem, on which so much depends, of 
 obtaining pure and safe water and ice would 
 be much easier of solution. 
 
CHAPTER XIII. 
 
 THE END OF THE STORY OF THE BACTERIA. 
 
 SO important is the subject of the causation 
 of disease by these minute organisms, 
 and so full is this field of the promise of 
 practical and far-reaching benefit to man, that 
 large numbers of scientific workers all over the 
 civilized world are eagerly and patiently de- 
 voting their time and skill to the study of the 
 disease-producing bacteria. 
 
 Great care and technical facility are required 
 to carry on successfully this kind of investiga- 
 tion, and it is not at all surprising, since we 
 have known how to study bacteria for but a 
 short time, that we should as yet know but 
 very little about many of the bacterial dis- 
 eases, or that we should often be mistaken in 
 our interpretations of what we do know. 
 
 There is the greatest temptation for workers 
 in this field to magnify the importance of 
 
 134 
 
THE STORY OF THE BACTERIA. 135 
 
 their own observations, or to claim as world- 
 reforming discoveries the results of imperfect 
 observation or misinterpreted facts. 
 
 The hope of the widespread prevention of 
 misery and disease, even in the dim dawn of 
 this new day, is so bright and cheering, and 
 so full is the air of high-sounding promise of 
 new and beneficent revelations, that one is 
 reminded of the description by Lowell of the 
 advent of a new phase of thought many years 
 ago in New England. " The nameless eagle," 
 he says, " of the tree Ygdrasil was about to sit 
 at last, and wild-eyed enthusiasts rushed from 
 all sides, each eager to thrust under the mystic 
 bird that chalk egg from which the new and 
 fairer creation was to be hatched in due time." 
 
 But in spite of mistakes and misinterpreta- 
 tions, in spite of the runaway enthusiasms 
 which now and again lead the disciples of the 
 new light to ignore the solid groundwork of 
 experience which was founded in the old, we 
 are daily gaining new facts and more com- 
 manding points of view, and the science of 
 medicine has entered upon a new and brilliant 
 epoch in its history. 
 
136 THE STORY OF THE BACTERIA. 
 
 The mysterious veil which has for so long 
 hung over some of the most widespread and 
 terrible of human diseases, is gradually being 
 drawn aside, and we now stand face to face 
 with known and understood and no longer, for 
 the most part, with mysterious and incompre- 
 hensible foes. 
 
 Ten years ago it would have seemed an idle 
 tale had one said that he could cultivate at will 
 in the laboratory the very living essence and 
 causes of such diseases as consumption, typhoid 
 fever, Asiatic cholera, diphtheria, and more of 
 the uncanny brood, and could study and ma- 
 nipulate them as the gardener does his larger 
 plants, and from the knowledge thus gained 
 plan new and efficient means for treating and 
 preventing the diseases which they cause. But 
 all this is strictly true to-day, as we have seen 
 in our review of man's invisible foes and the 
 ravages which they can cause. 
 
 And so at last we are at the end of our 
 story, so far as in such simple and hurried 
 fashion it can be told to-day. It is a story 
 which in parts is full of disquieting and un- 
 pleasant revelations, of facts which at first 
 
THE STORY OF THE BACTEKIA. 137 
 
 sight seem to make life under modern condi- 
 tions less simple and attractive, and Nature, if 
 we may so personify her, less man's friend. 
 But after all there are few things more dis- 
 quieting and unpleasant and unfriendly, to 
 most people, than are disease and death, and 
 these, sooner or later, will thrust themselves 
 into the attention of everybody, be he cognizant 
 or not of the varied disregard of nature's laws 
 which for the most part they follow. 
 
 It should not be forgotten by those who are 
 disposed to close their eyes to the disagree- 
 able and malign influences which, in the guise 
 of disease-producing bacteria so frequently 
 surround them, that the rights of others, as well 
 as their own mental ease, are at stake in this 
 matter. One has the right, so far as he is 
 himself concerned, to indulge in almost any 
 dietetic uncleanliness, or disregard of sanitary 
 rule with which he may elect to be satisfied ; 
 but he has no right to expose himself unneces- 
 sarily to the acquirement of such diseases as 
 will render him a source of either positive or 
 possible danger to his fellow men. 
 
 Among all th^ myriads of invisible agencies 
 
138 THE STORY OF THE BACTERIA. 
 
 which are ceaselessly working for man's weal 
 we have discovered a few which are his deadly 
 foes. We have seen that if one looks at the 
 matter intelligently, the means of largely avoid- 
 ing the evil effects of these dangerous earth- 
 neighbors of ours are comparatively simple and 
 effective, if we do not hide our heads, or shirk, 
 or waste our time in protestations and regrets. 
 There are many of the uncanny and dis- 
 agreeable things of life from which it were 
 better that most of us turned away our eyes. 
 But the avoidance of some of those forms of 
 illness, whose causes have been considered in 
 this little book, is so closely dependent upon a 
 general knowledge of their nature that the 
 offence of unpleasant revelations may, it is 
 hoped, be forgiven by the reader in view of the 
 ultimate and universal good which these lines 
 have been penned to foster. 
 
INDEX. 
 
 Abscess . . 
 
 Agar, as culture-medium for bacteria . -34 
 
 Air, as source of bacterial infection . 
 
 Albany, water supply of . . 
 
 Amoeba ... . 4 
 
 Asiatic cholera . ;. 9, ' ! 
 
 Bacilli ' . . ' 4 
 
 Bacillus of asiatic cholera . 
 
 " " tuberculosis 
 " " typhoid fever . 
 
 11 prodigiosus . . .48 
 
 Bacteria, action of cold on . . 
 
 li always derived from other bacteria . " 
 " antagonistic species of . 
 
 chemical substances formed by . 
 
 11 classification of . 39 
 
 color-forming . 46, 47i 4 
 
 '' consumption of, with food 
 " cultivation of, in agar . ... 
 
 41 " beef-tea 
 
 " " " kl gelatin -33 
 
 " " lk " potatoes . . 3 
 
 11 development of, in hay infusion 
 
 ' l disease-producing -53 
 
 " forms of . . J 5 
 
 " ik n co lonies of ... 
 
 " in air .... 10 9 
 
 "food ... 10 3 
 
 " kl ice . . 45 I 3 * V 
 
 " " relation to oxygen ... 44 
 "water . . ..... "6 
 
 " ll wine- and beer-making ...... 43 
 
 * l mode of multiplication of J 7 
 
 139 
 
140 INDEX. 
 
 Bacteria, movements of . "..- ." _ . . . 16 
 
 " nomenclature of . . . . . . . -39 
 
 " occurrence of . . . . .22 
 
 " of diphtheria . . . . . . . .96 
 
 " " measles ...... . 100 
 
 " tk pneumonia . . 99 
 
 " " scarlet-fever . . 100 
 
 " surgical diseases . -59 
 
 41 tuberculosis .... .70 
 
 " " typhoid fever ........ 84 
 
 " " yellow-fever ...... . 101 
 
 " phosphorescent ...... .41 
 
 " place of, in scale of being . . . . .15 
 
 ' k pyogenic ......... 68 
 
 il rapidity of multiplication of ... 17 
 
 " relations to putrefaction . . .20 
 
 " role of, in nature ...... .20 
 
 11 separation of species by fractional method . . 28 
 
 11 kt plate culture . . -35 
 
 " size of .... . . 15 
 
 " species of, mutually dependent . 50 
 
 " spores found in . .19 
 
 " staining ... .16 
 
 " struggle for existence among . . 18 
 
 Bacterial diseases, prevention of . . 79, 86, 104 
 
 lk poison, self-propagating . ...... 124 
 
 Beef-tea, as culture-medium for bacteria . . . . .29 
 
 Berlin, water supply of . 123 
 
 Bleeding Host, miracle of . .48 
 
 Blood cells ...... ii, 64 
 
 Blood poisoning . -59 
 
 Bread, color- forming bacteria on .... . . 48 
 
 Burning of garbage .... i3 2 
 
 Carbolic acid . ...... . 81,97,114 
 
 Cattle, tubercular .... 73^ Io6 
 
 Cells, as bacteria destroyers ... . ,66 
 
 " developed from the ovum ... 9 
 
 " elementary nature of . . . 2 
 
 Childbed fever .'.... .62 
 
 Cholera, Asiatica ..... 9 
 
 " bacillus ..... . 9 1 
 
 ik morbus ...... "7 
 
 Churches, bacteria in dust of .... . in 
 
 Consumption ..... -7 
 
INDEX. 141 
 
 Corrosive sublimate . . . . 
 Cremation of garbage . " . . - 
 
 . 4- ' 97 
 . 132 
 
 
 
 mode of conveyance of germs of, . . 
 44 spread of, by milk . . . , 
 Disease, nature of . . . . , . 
 44 producing bacteria . " . . , 
 
 ' -97 
 ' . .107 
 ~ 53 
 
 ' '53 
 
 44 as source of infection with tuberculosis . 
 44 bacteria of wound diseases in . . . 
 
 74 
 61 
 
 44 importance of, in ventilation . . . 
 
 .109 
 
 Erysipelas . . . . . . . 
 
 61 
 
 Feather dusters . . , . . . . 
 Fermentation , . . . . 
 Filters, domestic . . . . 
 Filth diseases . f . . , 
 Filtration ....... 
 
 . 113 
 43 
 . 125 
 94 
 lai, 126 
 
 Food, impure, as source of bacterial disease . . 
 Fowl, tubercular . . . . . 
 
 . 106 
 . . 106 
 
 Furniture in houses ...... 
 
 . . .114 
 
 Garbage, as a source of sanitary danger ... 
 Gelatin culture-media for bacteria . . 
 Germs . ... . . . 
 
 . 132 
 33 
 39 
 
 Holmes, Oliver Wendell ..... 
 
 .63 
 
 Ice, artificial ...... 
 
 
 44 typhoid bacilli in . . . . . 
 Inflammation, bacteria of . . . . . 
 
 . . 130 
 . . 64 
 
 Leucocytes . . : . . . . . 
 Living beings, characteristics of . . . 
 London, water supply of . . * 
 Lowell, J. R. . . . .'.-.. 
 
 . ' . . 64 
 3 
 123 
 135 
 
 Malaria . . . . . . 
 
 . . . IO2 
 
 Measles .... . . . 
 
 . . . ICO 
 
 Micrococcus . . . . . . , 
 Milk and diphtheria ..... 
 44 44 scarlet-fever . . . . . 
 
 3g 
 . 107 
 
 . 107 
 
142 INDEX. 
 
 Milk and tuberculosis . ";. 73 
 
 ik color-forming bacteria in, . . . . .47 
 
 Moon, old plan for communicating with ...... 31 
 
 Muscle cells . . . . . . . . . .10 
 
 Nerves . . . . . . "" . . n 
 
 New York, ice supply of .... 130, 131 
 
 " Vl water supply of . . . . . . .120 
 
 Olynthus\ . . . . . . . . . .6 
 
 Overcrowding and disease . ..... 104 
 
 Ovum . ....... 9 
 
 Pathogenic bacteria ........ 53 
 
 Philadelphia, water supply of ....... 122 
 
 Phosphorescent bacteria . ..... 41 
 
 Physiological division of labor in cells ...... 8 
 
 Plate cultures of bacteria ... . . . . . 35 
 
 Pneumococcus .... ... 99 
 
 Pneumonia and diphtheria . . > . 100 
 
 " bacteria of. . . . . , . .99 
 
 Poisons produced by bacteria ... 53, 66, 85 
 
 Potatoes for bacterial cultures ....... 30 
 
 Predisposition to bacterial disease . . . . 71, 93 
 
 Prevention of bacterial diseases . . . . . 79, 86, 104 
 
 Protozoa of malaria ..... . 102 
 
 Ptomaines . . ... . . 53, 66, 85 
 
 Pure cultures of bacteria . . . . . . . . 35, 38 
 
 Pus . . . . . . . . . . .64 
 
 Putrefaction . "~ . . . . . . .20 
 
 Pyogenic bacteria . ....... 68 
 
 Rooms, living-, pathogenic bacteria in . . . . . . no 
 
 Scarlet-fever . . . . . . . . . . 100 
 
 tk " spread of, by milk . . . . . . 107 
 
 Sewer gas and diphtheria ........ 99 
 
 " " lk typhoid fever ....... 88 
 
 Small-pox ... . . . . . 101 
 
 Spontaneous generation ... .... 22 
 
 Spores, in bacteria ... ..... 19 
 
 Sputum, dangers from, in tuberculosis . . . 75 
 
 Staphylococcus in wound diseases . . . . . .61 
 
 Streets, dirty, as source of infection ...... no 
 
 Streptococcus . .. 40, 61 
 
 of diphtheria . . . . . .97 
 
 Suppuration . ..64 
 
INDEX. 143 
 
 Surgical diseases, bacteria of -59 
 
 Theatres, bacteria in dust of . ... . in 
 
 Tubercle , 7' 
 
 bacillus . ... 7* 
 
 Tuberculosis ..... 7 
 
 11 cattle and fowl as sources of infection with . 73, 106 
 
 " germ of, in air .114 
 
 41 hereditary predisposition to . 7 1 
 
 " infection by, through the air ' . 74 
 
 " milk, as a source of infection . 73 
 
 " modes of preventing spread of .... 79 
 
 " sources of infection with . . . . .72 
 
 Typhoid bacillus, characters of ..... 84 
 
 " " in ice . . . . . . . 89 
 
 " " sewer gas . . . . .88 
 
 " " " water . . . . . .118 
 
 " " mode of entrance to body ..... 85 
 
 " poison produced by . . . . ' . 85 
 
 " fever and bacteria ... 84 
 
 " " bacteria in food and water . . . 108,118 
 
 " " sources of infection . ' . . . .86 
 
 Ventilation and bacteria . . . . . 109 
 
 " of churches and theatres . ., _ . . . in 
 
 " ' lk dwelling-houses . . . . . . .113 
 
 Water, bacterial analysis of . . . . % . 35. I2 4 
 
 " bacteria in.. .*-. - "0 
 
 " Croton, of New York .' . . 120 
 
 " filtration of . . . . . . 121, 125, 126 
 
 " from wells . . . . ' . 127 
 
 " sewage polluted . . . . 87,119,121 
 
 lk spontaneous purification of . .. . . 123 
 
 11 supplies of . . . . . . . 119 
 
 " supply of Albany, N.Y. ..... . 122' 
 
 " " Berlin and London ...... 123 
 
 " " New York ....... 120 
 
 " " Philadelphia . . .... 122 
 
 u typhoid bacillus in . . . . . . . 87, 118 
 
 Wells, as sources of water ..... . 127 
 
 White blood-cells 64 
 
 Winter cholera . . . . . . . 117 
 
 Yellow-fever . . . . . . 101 
 
H eyt*Boofc for 
 draining Schools for IRurses. 
 
 By P. M. WISE, M.D., President of the New York State 
 Lunacy Commission ; Medical Superintendent St. Law- 
 rence State Hospital ; Editor of the State Hospitals 
 Bulletin ; Professor of Psychiatry, University of Ver- 
 mont ; Member of the American Medico-Psychological 
 Association, etc. With an introduction by Dr. EDWARD 
 COWLES, Physician-in-Chief and Superintendent McLean 
 Hospital. 
 
 Two volumes, 16, illustrated, sold separately, 
 each . ' . . . . . . ,/ft?/,$i.25 
 
 This work will, it is believed, supply a present reed for training 
 schools. It is distinctly a text-book for training schools as distin- 
 guished from a text-book for nurses, and its arrangement provides 
 tor all the recitations in a two years' course. The first volume is 
 divided into thirty recitations or chapters, and includes anatomy, 
 physiology, hygiene (and allied subjects the atmosphere, ventila- 
 tion, etc.), the sick-room, infection and disinfection, observation of 
 symptoms, clinical recording, etc. Its arrangement is based upon a 
 graded system of teaching ; the first volume being adapted for the 
 first year's course. The second volume completes the course and 
 provides for every subject usually taught by recitation in schools for 
 nurses, leaving no requirement for auxiliary books. In fact the two 
 volumes furnish completely all the requirements of the training 
 school for a text-book. 
 
 4 ' It is an admirable piece of work. It is written very clearly, and 
 in language which can be very readily understood by the nurse. It 
 covers the whole ground, and contains a great deal of matter not to 
 be found in other books, and with the adoption of this book other 
 text-books will not be required for the training school." Dr. G. 
 ALDER BLUMER, Medical Superintendent of the Utica State Hospital. 
 
 "We believe this treatise will be adopted as a text-book in every 
 training school in the country. Its excellency is such as to justify 
 this belief, and surely training schools cannot afford to dispense with 
 the best." Btiffalo Medical Journal. 
 
 G. P. PUTNAM'S SONS, NEW YORK AND LONDON 
 
j^twtets. 
 
 A Text=Book for Training Schools for Nurses. 
 
 By P. M. WISE, M.D., President of the New York State 
 Lunacy Commission ; Medical Superintendent St. Law- 
 rence State Hospital ; Professor of Psychiatry, Univer- 
 sity of Vermont, etc. With an introduction by Dr. 
 EDWARD COWLES, Physician-in-Chief and Superintend- 
 ent McLean Hospital. 
 
 Second edition. Two volumes, illustrated, 16, sold 
 separately, each $ 1.2 5 
 
 " This text-book has been adopted by the ten State Hospitals of 
 New York, representing approximately four hundred pupils." 
 
 Dr. G. ALDER BLUMER (the medical superintendent of the Utica 
 State Hospital) says: "It is an admirable piece of work. It is 
 written very clearly, and in language which can be very readily 
 understood by the nurse. It covers the whole ground, and contains 
 a great deal of matter not to be found in other books, and with the 
 adoption of this book other text-books will not be required for the 
 training school." 
 
 A Text-Book of flateria fledica for Nurses. 
 
 Compiled by LAVINIA L. DOCK, graduate of Bellevue 
 Training School for Nurses, late superintendent of 
 nurses, Illinois Training School for Nurses, etc. 
 
 Third edition, revised and enlarged. Thirteenth thou- 
 sand. 12 . . . . . . . $1-50 
 
 ** The work is interesting, valuable, and worthy a position in any 
 library." N. Y. Medical Record. 
 
 "It is written very concisely, and little can be found in it to criti- 
 cise unfavorably, except the inevitable danger that the student will 
 imagine after reading it that the whole subject has been mastered. 
 The subject of therapeutics has been omitted as not a part of a 
 nurse's study, and this omission is highly to be commended. It will 
 prove a valuable book for the purpose for which it is intended." 
 N. Y. Medical Journal. 
 
 An Aid to Hateria fledica. 
 
 By ROBERT H. M. DAWBARN, M.D., Professor of Oper- 
 ative Surgery and Surgical Anatomy, New York Poly- 
 clinic. 
 
 Third edition, revised and enlarged by WOOLSEY 
 HOPKINS, M.D. 12 . ., . . . $1.25 
 
 G. P. PUTNAM'S SONS, NEW YORK AND LONDON 
 
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