Some Concepts in Mycology. William B. Brierley. 205 



high authority nor ancient status and rcspectabihty were 

 allowed to preserve them save as interesting historical relics. 

 In this note I wish to draw attention to certain concepts, 

 of importance in mycology and possessing many wider applica- 

 tions, which would perhai)s appear to merit some reconsideration 

 in the light of present knowledge. If the result of such con- 

 sideration be confirmatory, mycologists will hold and elaborate 

 their theses with the greater surety and profit. If the outcome 

 be to throw doubt upon accepted beliefs, that also is good, for 

 we shall no longer bow down before false idols. 



» I. The Species Concept. 



When a number of specimens are examined and the state- 

 ment is made that this organism is Ustilago Cardui, and that 

 organism Ustilago violacea, and so on, what is the connotation 

 of these terms? At first sight, perhaps, such a question may 

 seem pedantic and of mere academic interest; but these and 

 other fungi are disease-producing organisms and the problem 

 of their specific identity and recognisability is one most vital 

 to any clear formulation and indeed essential to any true 

 progress in mycology. 



Certain morphological characters A, B, C, D are noted in 

 a particular fungus and to it the name af3 is given. Another 

 fungus possesses the characters A, B, C, E, and receives the 

 name ay. A tjiird presents characters A,B,C, L, and is named 

 aS. The generic characters A, B, C these fungi all possess, 

 but they differ from each other in the one or more minor 

 characters D, E, L, and these serve to differentiate them as 

 species. If the morphological difference be, however, very 

 striking, the fungus may be given the status of a new genus, 

 whilst if inconspicuous the fungus may be graded as a variety 

 of some other already known species. For example, the 

 genus Phomopsis has certain morphological characters and 

 P. hysteriola, differing from P. striaeformis in certain minor 

 ways, is graded as a variety of the latter. If now a single 

 specimen were found with all the characters of P. hysteriola., 

 save only that it possessed large dumb-bell shaped spores, this 

 striking difference would certainly be sufficient to raise the 

 specimen to the rank of a new genus. And so a "Sylloge 

 Fungorum" has been evolved, the. criteria of all the several 

 ranks being confessedly arbitrary. 



This creation of new fungal species and their subsequent 

 determination from descriptive diagnoses is based on certain 

 assumptions which may perhaps be briefly expressed as 

 follows ; 



