48 Transactions British Mycological Society. 



groups, regarding the worth of the traditional concept of specific 

 entity, a result which is bound to cause the reflective mind to 

 ponder on the possible consequences to systematic Botany as a 

 whole of the extension of the methods of study by cultural and 

 hereditary observation which have led to the pronouncement of 

 these protestant doctrines among mycologists. Not that similar 

 signs are altogether wanting elsewhere. The geneticist has long 

 been at war with the systematist among the Angiosperms and 

 yet the systematist, though much battered, stoutly maintains 

 the essentials of his position. It is worth while enquiring how 

 this comes to be. The answer will not be without general interest. 



The arguments against the current method of systematic 

 mycology and particularly against its morphological bias have 

 been urged within the last few years by Brierley*. Fortunately 

 it need not concern us, from the present point of view, to dispute 

 the theoretical soundness of the position taken up by those of 

 this school, but it is vitally necessary to consider the relevance 

 of their contentions to the work of the descriptive systematist. 



Cut down to the bone the charge against current systematic 

 is simply that its "species" are not homogeneous units, and 

 further, that morphological comparison alone is incapable of 

 delimiting such units. For such a charge to have any revolu- 

 tionary effect it is plainly necessary for those who uphold it to 

 demonstrate that there exist, per contra, certain homogeneous 

 units, demonstrable experimentally by some means, to which 

 the unit term species should be transferred. If this can be 

 satisfactorily done, then, it is contended, the morphologically 

 established groups would have to be re-christened with a 

 substitute appellation and their heterogeneous nature confessed. 

 It is surely, however, pertinent to enquire whether any systema- 

 tist at the present day, when giving a new name, does seriously 

 imagine that in his new "species" he has defined an immutable 

 and inflexible unit, and, whether ingeniously elaborated argu- 

 ment to the contrary is not to a large extent knocking at an 

 already open door? The problem, so far as the systematist is 

 concerned, remains open ; it is his critics who have taken up an 

 exclusive position demanding rigid justification. 



Continued analysis of the species concept has led these critics 

 to the formulation of an ideal unit, which shall be, like a metre 

 measure, intrinsically invariable wherever found, although (to 

 carry on the analogy) its material manifestation (as of wood, 

 steel and so forth) may vary circumstantially ; and this is averred 

 to be the biological unit without which any systematic biology 

 is hopeless. This ideal unit is depicted as consisting of a per- 



* Brierley, W. B., Some concepts in mycology — an attepipt at synthesis. 

 Trans. Brit. Mycol. Soc. vi, p. 204 (1918). 



