170 



NA TURE 



[Dec. 25, 1884 



the second place, great as has been Dr. Koch's activity in the 

 study of Bacteria, the fact that he and others with whom he is 

 in relation have not found the " comma-bacilli" elsewhere does 

 not render it at all improbable that other observers might find 

 them elsewhere. This fallacy, viz., as to the perfection of Dr. 

 Koch's knowledge of all possible forms and modes of occurrence 

 of Bacteria, I have already pointed out above. 



On the supposition that these comma-bacilli never occur except 

 in the choleraic process it is of course impossible to maintain 

 (see the article in Nature of December 4, Fection (7), p. 98) that 

 the choleraic process merely favours the growth of the commas. 

 But Dr. Koih admits that they occur and flourish outside the 

 human body, in immediate connection with cholera dejecta ; also 

 that, when artificially cultivated, they flourish on substances not 

 derived from the human intestine. What proof is there that 

 they do not naturally continue so to flourish? Dr. Koch offers 

 none — he merely tells us that he has failed to show that they do. 

 It is not at all impossible, on Dr. Koch's own showing, that they 

 do — and if they do, what becomes of the argument as to the 

 impossibility of their introduction from external non-choleraic 

 conditions into the human body? 



The suggestion is also considered by Koch (and is cited in the 

 sect on of the article already mentioned) that, " as a result of the 

 disease (cholera), conditions ari-e which cause the transformation of 

 some ordinary bacterium into comma-bacilli." But, say Koch and 

 his English disciple, there is no evidence of such rapid transforma- 

 tion of o..e form of bacterium into another. Here we meet 

 with the special axiom of the pathologists to which I have 

 already referred. The opinion of those who are entitled to the 

 very greatest consideration, namely, the botanists Niigeli, Cien- 

 kow: ki, and de Bary, is that there IS evidence of such rapid trans- 

 formation of one form of bacterium into another. Without going 

 further than the case cited by the writer in Nature as "merely " 

 an alteration in pathogenic action, we have the instance of the 

 attenuation of the virulence of anthrax bacilli, and we have also 

 the case of the complete change of form of that same bacillus 

 into nostocoid chains of spherical elements when cultivated on 

 pork broth as shown by Klein. These two cases are by no 

 means isolated ones (see my own researches on Bacterium 

 rub scens, and also those of Zopf), but were they so the)- would 

 bv sufficient to establish the possibility of such changes in other 

 BacLeria and to des roy the argument based on the assumption 

 that such change is impossible. 



The "only conclusion which remains " (see paragraph (c), 

 section (7), in the article referred to) is therefore not that these 

 bacilli and the cholera processes stand in the 1 elation to each 

 other that the commas are cause and ihe cholera effect. On the 

 contrary, the only conclusion which remains is that WE do not 

 Kt o\Y whether the commas although not detected by Koch may 

 not be present in some parts of the healthy body, or flourishing 

 out-ide it on organic matter, or m >y be the result of the trans- 

 fer nation of some other bacterium, or may be the cause of 

 cholera. 



And the only way in which that ignorance can be removed 

 ha been very cle rly recogni ed by Dr. Koch and all other 

 recent writer-, previous to the attempt made by Koch in 1S04 to 

 pe suade the medical and scientific world that he had discovered 

 the cause of choler . The obscurity and uncertainty surrounding 

 the Bacteria is sticn that no value can be attached to any asserted 

 connection of a micro-organism wit 1 a disease as the cause of 

 that di ea e, which is no ba ed upen the experimental produc- 

 tion of the disease by the inoculation into healthy animals of 

 " pure cultures" of the suspected inier j-organism. Dr. Koch's 

 earlier statements on this subject are so precise and apt that I 

 cannot do better than quote tlrem here. He says in a pamphlet 

 published in 1882, entitled " Ueber die Milzbrandimpfung " : — 

 " The position which I take up is briefly as follows : — It is not 

 yet proved that all infectious diseases are caused by parasitic 

 micro-organisms, and consequently in each particular disease the 

 proof of the parasitic character of the disease must be furnished. 

 The first step towards this proof consists in the careful investi- 

 gation of all those parts of the body affected by the disease, in 

 order to establish the presence of the parasites, their distribution 

 in the diseased organs, and their relation to the tissues of the 

 body. ... It is not until a thorough knowledge has been ob- 

 tained in this way as to whether micro-organisms are pit sent in 

 the diseased parts, at what points they are present in perfect 

 purity — whether, for instance, in the lungs, spleen, heart's blood, 

 or elsewhere — that the attempt can be made to obtain the prool 

 that these micro-organisms are of a pathogenic nature, and thai 



they are more especially the cause of the disease in question. 

 With this object in view, they must be isolated by means of 

 'pure cultivation,' and when they have been freed in this manner 

 from all particles of the diseased body originally adhering to them 

 they must be introduced by inoculation into the same species of 

 animal in which the disease was observed, or, if that should 

 not be possible, into animals in which the disease in question is 

 known to occur with unmistakable symptoms. . . . An example 

 is afforded by the disease known in man as erysipelas. It has 

 been known for a long time that in this disease micrococci con- 

 stantly arc found in the lymph-vessels of the skin. But by this 

 knowud^- it certainly was not p'oved thai the micrococci arc the 

 cause of erysipelas. Now, however, that Fehleisen has recently 

 in ci eded by excision of portions of skin from erysipelas patients 

 (with every precaution against contamination by other bacteria 

 which might be accidentally present on the skin) in rearing these 

 micrococci in ' pure cultivations,' and in producing typical erysi- 

 pelas by inoculating the human subject with these isolated 

 micrococci, there can no longer lie any doubt that the micrococci 

 are, in fact, the cause of erysipelas, and that the latter is to be 

 regarded as a para-itic disease." 



This is the kind of proof which we require in the case of the 

 comma-bacillus, and its supposed causal relationship to cholera. 

 Dr. Koch has not succeeded in obtaining that proof. He has 

 tried, and has failed, to produce cholera by inoculation of " pure 

 cultivations " of his "comma." Cholera,at present, is not known 

 as a disease in animals. Nevertheless, Dr. Koch has urgently 

 and persistency declared that he consider it to be proved that 

 the comma-: acillus is the cause of cholera! After repeated 

 and public declarations of this conclusion, he is now making 

 experiments by introducing his "comma-bacillus," not through 

 the mouth, but by fistula- into the intestine of rodents. Those 

 who know the history of experiments on the production of 

 cholera in mice and other rodents will not be convinced, even 

 should Dr. Koch succeed in producing choleraic symptoms in 

 this manner, since the readine s with which cholera-like processes 

 are induced in these animals by abnormal conditions is uch as 

 to render them unfit subjects for these researches. 



II. We may now revert to ome of the statements made by 

 Dr. Koch, which in the preceding remarks we have accepted 

 without criticism. Even when this method is pursued, we find 

 Dr. Koch's conclusions unwarrantable; they will appear still 

 more so when we examine his position in detail. The writer of 

 the article in Natur.1 oi December 4 has omitted to notice a 

 very important charge brought by Dr. Lewis against Pr. Koch, 

 after the publication of Dr. Koch's address to the Medical Con- 

 ference at Berlin in last August. Dr. Koch, also, has remained 

 entirely silent in regard to this matter. It would be a very im- 

 portant thing it he would even now frankly reply to it. Dr. Koch 

 and his defender assert that the " comma-baoilli " were found 

 by Dr. Koch in cholera cases in Egypt, and also in specimens of 

 intestine sent to him from India previous to his going there. 

 Dr. Timothy Lewis, on the other hand, asserts that Dr. Koch 

 had not recognised the "comma-bacillus" previously to his 

 visit to India, and that in Egypt Dr. Koch attributed the causing 

 of cholera to a totally different organism from lint which he put 

 forward. after his arrival in India, and that, although he had thus 

 shifted his ground, Dr. Koch did not admit at th time, and has not 

 since admitted, that lie was at one time convinced that cholera 

 was caused by one organism, and a few months after was con- 

 vinced that it was caused by another. 



Thi- charge is of importance for two reasons. If true, it 

 miit tend to lessen the confidence reposed by some in Dr. 

 Koch's conclusions ; and, secondly, it must also les-en our belief 

 in the cand iui with which he states all the circumstances 

 attending his observations and inferences. 



The following quotations from the official reports sent h me 

 at intervals by Dr. Koch, coupled with the fact that he 1' 

 not replied to Dr. Lewis on this point, though he ha replied 10 

 him on other points, seems to leave little room for doubt that Dr. 

 I ,ewis is perfectly correct in the very grave charge which he has 

 br ught against Dr. Koch. 



In his report from Alexandria, September 17, 1883, Dr. Koch 

 says: — " These bacteria are rod-shaped, and belong accordingly 

 to the genus bacillus ; they resemble mo t nearly in size and 

 form the bacilli found in glanders" (which are straight: see 

 woodcut, fig. A). In his report from Calcutta, dated January 9, 

 1884, he says: — "The microscopic examination demonstrated 

 the presence of the same bacilli in the cholera intestine as had 

 been found in Egypt." In a further report, dated February 2, 



