Some Concepts in Mycology. William B. Brierley. 213 



so, but that even as a temporary working hypothesis it is 

 valueless and only increases the existing confusion in mycology. 

 The utmost that may be achieved by the practical application 

 of such a concept, and this is the systematic mycology of 

 to-day, is the minute description of ecologic variants and 

 growth forms, the "ccads" of Clements(6). The true species 

 implying identity of constitution has no existence in such a 

 concept. 



It would be a prohtable and fascinating study to examine 

 in some considerable detail the philosophic bases for a species 

 concept, beginning from the known facts of mycology, but the 

 most that is feasible here is merely to indicate certain of the main 

 directions in which such a consideration would perhaps progress. 



At the present time we have no knowledge of living organisms 

 apart from some particular environment, such environment 

 varying from a stump in a tropical forest to a standardised 

 synthetic medium in a laboratory. The visible organism is 

 a morphological entity which may as we have said shew a 

 different morphological facies under other environmental 

 conditions. Each individual is therefore a growth form or 

 "ecad," and every ecad may be regarded as being the morpho- 

 logical expression of the resultant of two interacting series of 

 forces. One of these force systems is the living matter or the 

 organic individual which itself is an almost infinite complex 

 of metabolic reactions in a colloid substratum. The other 

 force system is the infinite complex of physico-chemical reactions 

 which constitutes any particular environment. Thus the 

 morphological expression of the resultant of the interaction of 

 two force systems represented by a certain organic individual 

 and an aqueous environment, is that growth form which we 

 term the aquatic variant of Ranunculus aquatilis. The same 

 force system which is the organic individual, interacting with 

 a second force system which is certain conditions of develop- 

 ment on land, gives a resultant the morphological expression 

 of which is the terrestrial variant of Ranunculus aquatilis. 

 One may draw illustrations from chemical phenomena and the 

 analogies may have far greater significance than merely an 

 illustrative value. The force system copper, interacting with 

 the force system nitric acid, produces a resultant having the 

 facies of copper nitrate, but the resultant of the interaction 

 of copper with a different environment, sulphuric acid, is 

 expressed by the substance copper sulphate. From the phe- 

 nomena of crystallisation one could adduce much more exact 

 analogies. 



But the existing organic entity is far greater than the morpho- 

 logical structure which is its visible expression. Much more 



