Dec. 25, 1884] 



NATURE 



169 



or in non-parasitic conditions; the second being that no one, 

 with the exception of Dr. Koch and one or two of his pupils, 

 has any real first-hand knowledge of Bacteria which is of any 

 moment. It is hardly necessary to insist in the pages of a 

 scientific journal upon the fact that these really are misconcep- 

 tions. Our knowledge of the Bacteria is in its infancy — and Dr. 

 Koch's knowledge of them is no more than that which an 

 industrious worker may be expected to have gained in the 

 course of very special observations in regard to a limited class of 

 these organisms (the pathogenic class) extending over a few 

 years. On the other hand, the study of Bacteria has been prosecuted 

 from three separate points of view during the past fifteen years 

 by a number of observers, who may be grouped according to 

 their point of view as the botanists, the chemists, and the patho- 

 logists. It is undeniably the fact that neither the chemists nor 

 the pathologists have given much heed to the work of the 

 botanists, and that the results attained by the three groups of 

 workers have not feen brought into harmony. To the medical 

 world the special investigations of the pathologists alone are 

 familiar, and undue weight has been given on the one hand to 

 generalisations which ignore the more widely-based conclu- 

 sions of the botanists, and on the other hand to the introduction 

 into the pathological arena of methods of study which are not 

 new or original, but have been borrowed from the botanists, 

 whose opinions are nevertheless ignored or dismissed with little 

 consideration. As examples of these tendencies I may quote 

 the reiterated assertion by Dr. Koch, and the pathological 

 school, of the conclusion (upon which they base many very 

 momentous arguments) that the forms and the activities of 

 Bacteria are absolutely fixed and limited — that micrococci only 

 produce micr cocci, bacilli only bacilli, spirilla only spirilla, 

 and that none of these forms vary from generation to generation, 

 or can be produced from another of these forms, and that a 

 micro-organism producing a particular disease or a particular 

 ferment cannot in the course of generations lose the property 

 of producing that disease or that ferment, and vice versd that 

 one not having such properties cannot, in the course of human 

 experience, acquire them. This axiom of the pathologists as to 

 fixity of form and property, is entirely opposed to the con- 

 clusions of the botanists, who reason from a much larger area of 

 observation. Such authorities as Nageli, Cienkowski, and de 

 Bary are amongst those who maintain, in opposition to the 

 pathological specialists, that wide range of form and wide range 

 of physiological activity are possible in one species or " race " 

 of Bacteria. To this subject I propose to revert in detail, on a 

 subsequent occasion. As an example of the borrowing of 

 methods by pathologists from botanists, I may quote the tact 

 that it is customary in the writings of pathologists to attribute 

 the gelatine method of cultivation to Dr. Koch, and to attach 

 some additional weight to his conclusions on the ground that he 

 has originated this and other ingenious methods of research. As 

 a matter of fact, the gelatine method of cultivation, which is only 

 a modification of the potato-slice method, is due to the botanist 

 Brefeld (as acknowledged by Koch himself). 



Whilst it appears that there has not been on the part of the 

 pathologists engaged in the investigation of Bacteria such an 

 acquaintance with, and appreciation of, the work of the botanists 

 as would be conducive to sound conclusions, it is true that the 

 chemists also have frequently failed in the same way. Much of 

 the work of M. Pasteur on Bacteria is difficult, if not impossible, 

 to verify or to use in any way, on account of the fact that he has 

 not, in prosecuting his studies on these minute plants, made 

 correct use of the conceptions and terminology of the botanists, 

 and has on the other hand used that terminology erroneously 

 and in a special sense. 



Dr. Koch has given a very remarkable proof of the isolation 

 of his knowledge and work from that of the botanists (among 

 whom without question the most tru-tworthy conclusions in 

 this department of knowledge are likely to be found) by his use 

 of the term "spore" in his description of the tubercle-bacillus 

 discovered by him. The " spore " of a bacillus, as shown more 

 especially by the minute studies of the botanist Oscar Brefeld, 

 is a very special structure formed within the filament of the 

 bacillus by a modification of apart of its protoplasm, and pro- 

 vided with its own special capsule. Koch actually describes the 

 whole of the constituent protoplasm of a tubercle-bacillus 

 which has a moniliform arrangement as a series of "spores," 

 although it is quite clear that there is nothing in common 

 between the arrangement of the entire protoplasm of a bacillus 

 in the form of a string of micrococci and the periodic and special 



elaboration of the spores of the hay and anthrax bacilli. 

 The so-called " spores " of the tubercle-bacillus are spores 

 only in the sense that all segments of bacteria which can be 

 detached and multiply are spores (Arthrosporeae of de Bary) and 

 do not justify the distinction which Koch makes when he states 

 that the tubercle-bacillus is characterised by producing spores, 

 whilst stating that spirilla, such as the spirillum of relapsing 

 fever (which breaks up into segments capable of growth), do not 

 produce spores. 



Bearing in mind these facts as to the attitude of different 

 schools of bacteriologists, let us examine the claim put f >r\vard 



u 



Outline of the bacillus of glanders (which Koch says resembles the 

 comma f). b, Diagram of Bacillus subti is of hay infusion during 

 sporulation ; 1, sheath of the bacillus ; 4, transverse septum ; c, coat of 



a^spore ; d t content of a spore ; e, protoplasm surrounding the spore, which 

 disappears entirely when the latter is fully formed ;/, empty or sterile 

 segment, c, Tubercle bacillus ; t'ie protoplasm is arranged in moniliform 

 masses (e), which are erroneously called " spores " by Koch D, Diagram 

 of hay bacillus in vegetative state ; the protoplasm is arranged in block- 

 like masses (<"), comparable to the moniliform masses of c. E, Spirillum 

 dividing into commas, f, Commas (stated by Koch to be identical in 

 form with the glanders bacillus, fig. a). 



by Dr. Koch, and on behalf of Dr. Koch, by the writer in 

 Nature of December 4, p. 97, to have discovered that a certain 

 comma-shaped bacterium is the cause of cholera The writer 

 in Nature gives a summary of the various peculiarities of 

 growth, form, and properties which Dr. Koch states he observed 

 to be characteristic of a micro-organi-m occurring in the intes- 

 tine of persons dead of cholera. He then observes : "Micro- 

 organisms presenting all these characteristics are the bacilli 

 described by Koch ; organisms presenting only some of the 

 characteristics, such as microscopical appearance, but differing 

 in other points, are not Koch's comma-bacilli." To this con- 

 clusion, it is quite impossible in our present state of knowledge 

 to assent. Its acceptance by the writer of December 4 renders 

 it improbable that he will ever be convinced that Dr. Koch has 

 formed an erroneous conclusion. The pretension put forward on 

 behalf of Dr. Koch amounts to this, viz., that he has ascertained 

 all the properties of this organism, that he cannot possibly have 

 made any mistake, and that it is more probable that this organism 

 has, since Dr. Koch left India, disappeared from existence, and 

 been replaced by another very much like it, but not quite the 

 same, than that any subsequent observer should be able to 

 correct the hurried observations made by I )r. Koch when he 

 was there. Such a pretension, were it advanced in regard to 

 an animal or plant belonging to a group of exceedingly well- 

 defined and highly-organised species would be unreasonable, 

 but when put forward in relation to a representative of a group 

 consisting of such minute, unstable, protean, and ill-understood 

 species as are the Bacteria, must lead us to question altogether the 

 impartiality and critical faculty of those who make it. 



Admitting, however, for a moment that Dr. Koch's comma- 

 bacillus is as peculiar as he supposes, admitting, as Dr. Koch 

 originally implied by his silence as to the existence of other 

 comma-shaped bacteria, that it is utterly unlike anything at 

 present Known in shape as well as in its action on gelatine, 

 Dr. Koch has not proved or even rendered it greatly 

 probable that this comma-bacillus is the cause of cholera, even 

 when we accept his statement that "he has always found the 

 comma-bacilli constantly accompanying cholera, and that he has 

 never found them elsewhere." In the first place, it is quite 

 certain both from Dr. Koch's reports and from the observations 

 of others, that cases of cholera occur in which these commas 

 are not abundant, in fact are insignificant ; n quantity ; and in 



