Some Concepts in Mycology. William B. Brierley. 219 



Weidemannd'^) and a few more recent investij^ators have 

 gone further and foUowed the bacteriologists in giving formulae 

 for a considerable number of media and detailed notes as to 

 reactions upon such media. 



In bacterial studies any particular organism may be repre- 

 sented by a number which defines exactly its physiological 

 constitution. If the species concept as described by Lotsy, 

 which is the physiological interpretation put forward in this 

 paper, be accepted, one mtiy anticipate the elaboration of some 

 similar numerical system for recording the salient physiological 

 characters of an organism which will be applicable in mycology. 

 This is the final ideal of the quantitative method, and the 

 development of this method is imperative if order is to appear 

 from chaos. 



II. Edncability of Fungi. 



A second concept to which attention may with profit be 

 directed is that of the "educability of fungi" or the induction 

 by suitable treatment of permanent modifications in their 

 biochemical, morphological or other properties. The concept 

 of the educability of the lower organisms is almost universally 

 held either explicitly or implicitly by microbiologists, but 

 rarely is it formulated as a general principle, and even more 

 rarely expressed in concrete terms. A survey of the literature, 

 however, and still more, personal contact with those investi- 

 gators interested in the behaviour of the lower organisms, 

 clearly shews that this concept permeates all thought and all 

 consideration of the problems involved, and that the validity 

 of many far-reaching conclusions is bound up with its truth. 

 Every day bacteriologists attenuate or augment the virulence 

 of cultures of pathogenic organisms by well-known technique, 

 observe the fermentation of sugars by cultures which before 

 treatment were unable to form the requisite enzymes, find 

 pigment produced where no colour was originally. "Systematic 

 cultivation of colon and typhoid bacilli in the hands of Twort, 

 Pcnfold and others seems to have shewn that agglutination as 

 well as fermentation characteristics can be artificially changed. 

 Furthermore, colour producing organisms like the prodigiosus 

 can be artificially changed to colourless strains, and it is well 

 known that certain micro-organisms rapidly lose their virulence 

 when cultivated, and that the virulence can only be brought 

 back by passage through animals. Rosenow claims recently 

 to have converted hemolytic streptococci into typical strepto- 

 coccus viridans, pneumococcus mucosus, and pneumococcus- 

 like organisms." The foregoing passage is quoted from one 

 of the latest and best known treatises on bacteriology{i5). 



