1915] 



ATKINSON PHYLOGENY IN THE ASCOMYCETES 



323 



Stahl, 77, Baur, '98, Bachmann, '13; for the Laboulbeniales, 

 Thaxter, '96, p. 225), may be classed as secondary or accom- 

 panying sexual phenomena. It does not necessarily follow 

 that the sperm nucleus reaches the egg or fertile portion of 

 the archicarp. The trichogyne changes taking place after 

 the entrance of the sperm into, or its connection with the re- 

 ceptive terminal cell, are not dependent on the final fate of the 

 sperm, i. e., whether it reaches the egg or not. They are ante- 

 cedent phenomena and in no sense a proof that fertilization 

 has taken place. These disintegration changes, initiated, it 

 would seem, by the influence of the sperm on the receptive cell 

 of the archicarp, terminate the vegetative growth of the archi- 

 carp and thus the reflex upon the fertile portion at the middle 

 or base releases the ascogenic cells from the inhibiting influ- 

 ence of the vegetative phenomena, and they then proceed with 

 the modified sexual process among the ascogonial nuclei which 

 may be now associated in sexual pairs, or this pairing be post- 

 poned to some period in the development of the ascogenous 

 hyphae. 



Origin of spermatid in the Ascomycetes. — The presence of 



the so-called spermatia in many lichens and other Ascomy- 

 cetes, associated at the same time in numerous instances with 

 the trichogyne-like termination of the archicarp, is one of the 

 major pieces of evidence brought forward in supporting the 

 doctrine of the red algal origin of the sac fungi. If we accept 

 this doctrine, then in the Ascomycetes we must read the his- 

 tory of the antheridia in the following order : They appeared 

 first as free structures, spermatia, abjointed from spermatio- 

 phores, large numbers of which were crowded in highly spe- 

 cialized receptacles. 



At the next step there were few, imbedded, isolated anther- 

 idiophores to which a few spermatia remained attached, until 

 finally the stage was reached where spermatium and anther- 

 idiophore were merged into the simple antheridium. This 

 doctrine also requires that along with the change from free 

 spermatia to the simple antheridium, there was a transition 

 from the condition in which the spermatia do not function to 



