PERSONAL VIEWS OF PHYLOGENY 193 



even suspected from the standpoint of contiguity, to be 

 associated with any higher form. 



I incline to the opinion that in numerous instances 

 the sexual stage has completely disappeared, leaving the 

 conidial form alone. Assuming for the moment this idea 

 to be correct, should such isolated conidial forms be con- 

 sidered as genuine species ? All to whom I have put this 

 question say, no ! 



Returning for a moment to the origin of the conidial 

 generation, we find that it first appeared as a supplement 

 to a sexual condition ; the two phases might be in organic 

 continuity, that is, originating from the same mycelium as 

 in Peronospora,) Hypoxylon, etc., or the two generations 

 may be organically quite distinct, one generation originat- 

 ing from the mycelium formed by reproductive bodies 

 produced by the other generation, as in Sderotinia^ where 

 Woronin has shown that certain species are even heteroe- 

 cious. Now in these examples the conidial form is not 

 an entity, but, along with the sexual phase, constitutes a 

 species. 



As previously noted, even in the earliest group, the 

 Phycomycetes, the sexual phase was on the wane ; I 

 believe it to be generally accepted that the sexual phase of 

 Plasmopara infestans has disappeared, the conidial phase 

 only remaining, yet I am not aware that any one has 

 objected to this conidial form being accepted as a species, 

 or that any one has suggested its removal to the Hypho- 

 mycetes, to which group technically it belongs. Numerous 

 other accepted species included in the Phycomycetes are 

 only represented by the conidial phase. Now this must 

 surely be wrong if a conidial condition cannot be accepted 

 as a species. 



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