PERSONAL VIEWS ON PHYLOGENY 189 



from a group of algae including Vaucheria and 

 allies. 



Conjugation by gametes, as met with in the Zygosporeae, 

 is a modification of the older sexual form by antheridia 

 and oogonia, inherited by fungi from the algae. In many 

 species the two gametes are absolutely indistinguishable 

 as to size or apparent function ; the transition from anther- 

 idia and oogonia is, however, indicated by such species as 

 Rhizopus nigricanS) where one gamete, the male, is much 

 smaller than the other and remains unseptate. The much 

 larger or female gamete has a septum formed near the free 

 end which comes in contact with the male gamete, and this 

 cut-off portion of the female gamete is the receptive cell, 

 and eventually becomes the zygospore. The zygospore 

 mode of reproduction had but a brief period of existence, 

 and disappeared during the reign of the Phycomycetes. 



The evolution of the conidial phase, with its septate 

 mycelium and means of living in the air, must be con- 

 sidered as the first indication of an attempt to establish a 

 definite group apart from the algae, and the two succeed- 

 ing primary groups, the Ascomycetesand the Basidiomycetes, 

 are simply extensions of this conidial phase, originating with 

 the Phycomycetes. The old monosiphonous sexual stage, 

 not being able to accommodate itself to aerial conditions, 

 survived for a time, but could not emerge from the matrix or 

 substratum, and did not extend beyond the Phycomycetes. 



In the Ascomycetes both vegetative and reproductive 

 portions are built up from the hyphae originating in the 

 conidial condition of the Phycomycetes ; even the sexual 

 organs, whether functional or effete, spring from distinctly 

 septate mycelium. 



In the Phycomycetes both sexual organs and conidio- 



