414 



NATURE 



\_March 4, 1886 



Morphologic der Pilze," p. 511, says, in regard to the question 

 of species among the different forms of Bacteria : — ■" There exist 

 two views on this subject which are, at any rate in appearance, 

 totally opposed 10 one another. The first is, as I think 

 erroneously, ascribed to Cohn. . . . Cohn distinguishes merely 

 wliat we have above spoken of as form genera and form-species. 

 Tiie other view in its most extreme form amounts to this, that 

 ill! distinction of species among the Bacteria is denied, and all 

 forms are regarded as modifications of a single species or what- 

 ever else it may be called, and these modifications can be trans- 

 formed by cultivation into one another reciprocally. This view 

 was (if we leave out of consideration older intima'ions of a 

 similar nature) set up in opposition to Cohn's classification by 

 Lankester in 1S73, and by Lister ; and in 1874 carried to such a 

 length by Billroth, that he united all the forms of Schizomy- 

 cetes known to him under one collective species, his Coccobac'cria 

 si'ptka. It received later a support through the views which 

 Nageli (1877) expressed in the words 'I have investigated 

 during the past ten years many thousands of Bacterian forms, 

 and I could not maintain (if I except Sarcina) that there was 

 any need for a separation into even two specific forms.' , 

 Nageli, however, adds that he by no means maintains that all 

 forms belong to one single species : it were a bo'd thing in his 

 opinion to express a definite conclusion in a matter in which 

 morphological observation and physiological experiment leave 

 the investigator so much in the lurch. He expresses himself 

 again in the same sense in 1S82. He nevertheless is, when 

 carefully considered, in agreement with Cohn's fundamental 

 conception, since Cohn erected his form-genera and his form- 

 species (the latter based on physiological properties) primarily 

 in order to gain a provisional survey, and irrespective of tlie 

 question (as he distinctly states) as to whether as thus distin- 

 guished they correspond to natural species. 



" Nageli's words above-cited contain a pregnant criticism of 

 the whole controversy, so far as it had tlien gone. Both parties 

 failed to bring forward (as is especially the case in Billrotli's 

 book) the only certain basis for their opinions, namely, the strict 

 observation of the continuity or the non-continuity of the forms 

 or species in question. In the absence of this, our judgment 

 could only remain suspended, more especially since the forms in 

 question are minute, very like to one another, often mixed 

 together, and consequently easily to be mistaken for one another 

 in the absence of quite strict observation. Lankester certainly 

 came somewhat nearer towards establishing a special case of 

 strictly-observed continuity, since the forms of his Bactct-inrn 

 riihcscens [Beg^iatoa roreo-pirskina) gave evidence of their con- 

 nection with one another more clearly by their characteristic 

 coloration. Strictly-made morphological and developmental 

 researches are now to hand. They have demonstrated that the 

 forms known as Cocci, Rod.s, Threads, &c., are phases of growth 

 ( VVuchsformen)." 



Thus writes Prof, de Bary in 1884. To some extent I have 

 reason to thank him for the recognition which he gives to my 

 position in this matter. But I cannot think that he has given a 

 correct statement of my relation to the conclusion which he 

 finally adopts when he associates me with Lister, who derived 

 Bacteria from Fungi, with Billroth, wh^ massed all Bacteria under 

 one collective species, and with Nageli, who declared that he 

 did not see grounds for distinguishing as many as two. 



The view which I put forward in 1873 is precisely that which 

 Prof, de liary now espouses, and I think I may very rightly 

 object to its being confounded with the extreme and exploded 

 theories of other naturalists. As to the "strict morphological and 

 developmental researches " which now have made my doctrine 

 of the pleomorphisni of the .Schizophytes acceptable to Prof de 

 Bary, 1 beg to point out that thej'do not differ in character haxa 

 my own researches on Baclerhim rttbefcens. Prof, de Bary very 

 properly cites the later researches of Cienkowski, Neelsen, 

 Hansen, and Zopf as the chief amongst those which have tended 

 to establish thit view as to the forms and species of Schizophyta 

 which I promulgated in 1873. They have done so, twt by 

 affording us any stricter evidence of actual observation of change 

 of form taking place under the observer's eye, but by multiply- 

 ing cases similar (in regard to the kind of observation made) to 

 that published by me in 1S73, viz. observations of the juxta- 

 position and structural continuity of dift'erent forms, and of the 

 co-existence with extremely divergent forms of abundant inter- 

 mediate forms. 



In relation to the attitude taken up by one of the above-named 

 observers, I have something further to say. Dr. Zopf has made 



valuable researches on various Bacteria and on the Mycetozoa, 

 and has published the best systematic account of each of these 

 groups which has appeared. In his quarto memoir (Leipzig, 

 1882) on the Schizophyta, as well as in the smaller hand-book 

 which he has since produced, Zopf gives a reference to my 

 memoir on " A Peach-coloured Bacterium." He has himself 

 repeated my observations on that organism, but he has entirely 

 abstained from pointing out in the text of his work how far his 

 observations are simply repetitions of those published eleven 

 years previously by me (which they are almost entirely), and he 

 has in the most exact details adopted the view as to the pleo- 

 morphism of Bacteria which I then put forward, and on pre- 

 cisely the same grounds, without stating that he had been antici- 

 pated by me in this respect. 



Not only this, but Zopf actually goes out of his way to ascribe 

 to me a view differing from his own, and one which I have never 

 suggested. Either Zopf is writing about my views without 

 having troubled himself to ascertain what they are, or he is pur- 

 posely misrepresenting them, when he says (" Morphologic der 

 Spaltpflanzen," 1S82, p. v.) : " Die Annahme Billrotli's und 

 Lankester's dass alle Spaltpilzformen nur Einer einzigen natur- 

 historischen Art oder Gattung zugehoren, lasst sich nicht 

 aufrccht erhalten." 



I think Dr. Zopf will find it difficult to bring forward a cita- 

 tion from any writing of mine in which I have hinted, even in 

 the remotest way, that "all the forms of Schizophyta belong to 

 a single natural species." Billrotli's declaration on this subject 

 was published a year after my statement of the pleomorphic 

 nature of the numerous natural species of Schizophyta, and never 

 appeared to me to have any foundation in a general botanical 

 experience, but to be the result of the restricted observations of 

 a pathologist. 



To remove all possibility of further misapprehension, I may 

 be allowed to quote my own words ("A Peach-coloured Bac- 

 terium," Quart. Jottrn. Mic. Sci., 1873, p. 410) : — 



" The series of forms which I have found in the growth of 

 Bacterium rii/iescens leads me to suppose that the natural species 

 of these plants arc within proper limits 'Protean.' . . . The 

 natural species among the Calcispongire have been shown by 

 Haekel not to correspond at all with the series of /or//is distin- 

 guished by his predecessors. . . . It seems e.xceedingly probable 

 that the same manner of regarding the Bacteria will have to be 

 adopted, Cohn's tribes and genera taking the position of an 

 artificial or formal system, whilst the natural species must be 

 based upon some of those more profound characteristics which 

 Cohn has himself indicated to us in his divisions — saprogenous, 

 chromogenous, pathogenous. The indications of natural species 

 do not lie under our hands in the case of the Bacteria, but have 

 yet to be sought out." 



I have now, I think, sufficiently pointed out the position of my 

 publication on Bacterium rubesccns in the history of the modern 

 doctrine of the pleomorphism of the Bacteria. It wdl accord- 

 ingly be readily understood that I cannot contentedly see this 

 doctrine referred to, as it was recently in your columns by my 

 friend Dr. Klein, as "Nageli's theory of the pleomorphism of 

 the Schizophyta," since Nageli's view was announced four years 

 after my publication, and is not identical with that at present 

 accepted by De Bary, Zopf, and others, which is, in fact, 

 precisely that put forward by me in 1873. 



Equally objectionable as falsifying the history of knowledge 

 by assigning to one individual the property of another is a state- 

 ment in your review of Mr. Crookshanks's " Practical Bacterio- 

 logy" (Nature, February 18. p. 361). The reviewer quotes and 

 apparently indorses a statement by Mr. Crookshank, whose 

 book I may observe, though useful in many ways, is wanting in 

 accuracy and in references to original .sources. The passage to 

 which I allude is as follows : — " ' Researches,' writes our author," 

 " by competent observers have quite recently clearly de- " 

 " monstrated that several micro-organisuis in their life-cycle " 

 " exhibit success Wely the shapes characteristic of the orders " 

 " of Cohn. This had as early as 1873 been observed by " 

 " Lister in a Bacterium in milk. Lister detected forms of" 

 " Cocci, Bacteria, Bacilli, and Streptothrix genetically con- " 

 " nected.' Recent observers also have obtained similar " 

 " results, so that the very foundation of Cohn's classifica- '" 

 " tion has been shaken, and we are left without possessing " 

 " a sound basis for classification into genera or species." 

 In the original work of Mr. Crookshank (p. no) I find the 

 names of Cienkowski, Neelsen, Zopf, Van Tieghem, and others 

 of my successors in this field cited, but no reference is made to 



