174 BACTERIA IN THE SPUTA 



gelatine, on which not all of the above mentioned microbes thrive. 



Black, through his own researches, has found in the contents 

 of the mouth, SU'cptococciis continuosiu, Straphilococcus mediiis, 

 Staphylococcus magnus, Coccus cu?fiulus minor, and Bacillus 

 gelatogenes.''' 



We have not been able indeed to convince ourselves that, from 

 those experiments of cultures, a basis may be established for the 

 identification of the species of bacilli or bacteria, owing to their 

 unlimited polymorphism, according to the various nourishing media 

 and the different conditions of their surroundings ; so that, wher- 

 ever the decisive proof of the fructification is wanting, the results 

 of the cultures for creeping or immersed vegetation cannot be 

 freely accepted as the same. In doing so we might run the risk 

 of multiplying the species and the true or supposed pathogenic 

 properties of bacteria, ad infinitimi. 



Different particles or cellules of the same organism may, in 

 fact, need various nutrient media ; they may liquefy certain sub- 

 stances, and separate others of a very different nature ; as, for 

 instance, the bony corpuscle, the hepatic cellule, the blood cor- 

 puscle, the Ilenal Epithelium, etc. The poison of insects or 

 snakes is not diffused throughout their organism, but it is secreted 

 by special glands. Likewise, in the higher vegetation, the leaves, 

 the roots, the buds, the seed, etc., often contain principles or alka- 

 loids totally different from the other parts. And the same particle 

 or cellule can assume various forms according to its stage of deve- 

 lopment, its surroundings, or nourishing pabulum. 



Furthermore, the virulence of bacteria may decrease or disappear 

 in certain cultures ; increase or reappear in others. Now, if the 

 virulence constitutes for itself a truly specific character at every 

 step, we shall have to admit, in those microbes, changes of species; 

 and thus, in order to defend the true and well-thought pleomor- 

 phism, we must necessarily fall into an illimited and unlikely one. 



However, referring to the six species of micro-organisms 

 admitted by Miller in the cavity of the mouth, we, with due 

 respect for the author, cannot abandon the opinion (which, 

 although old, is not ours) of the fundamental unity of all 

 these forms, and their derivation from a single species, the Lep- 



* Miller, die Mikroorganistneil dej- Mundhohl, etc., 1889, pp. 43 — 75. 



