1915] 



ATKINSON — PHYLOGENY IN THE ASCOMYCETES 



349 



elation to the red 



The analogy at least between the 



trichogyne of the red algae and that of the Ascomycetes is 

 very striking. The evidence brought forward by Stahl (77) 

 and others of the relation of the trichogyne to the ascogo- 

 nium in the lichens, together with the fusion of spermatia to 

 the trichogyne, followed by the gradual and peculiar degenera- 

 tion of the latter and the subsequent development of the as- 

 cogenous threads, was generally accepted as proof of fertil- 

 ization in the ascogonium by a spermatium. Also the 



(Fisch, '82; Frank, '83) and 



hich similar struc- 



studies of Poly stigma rubrum 

 Gnomonia erythrostoma (Frank, '86) 

 tures and phenomena were observed at that time, were gen- 

 erally accepted as indicating a well developed condition of 

 sexuality. These studies gave a great impetus to the theory 



ggested by Sachs 



96) that the A 



had their 



cestors 



from the red algae, or that the two groups had 



common. This theory has taken 



deep root 



and probably is accepted by a maj 



of botanists even 



at the present time, especially by those who are not special 



students of the fun 



5 



It should be stated also that a number 



of our foremost students of the fungi, perhaps a majority of 

 them, are firm disciples of this theory. 



Recent investigation, however, including a cytological study 

 of several of the now classic types, including Collema (Bach 



mann, Miss F. M., '12, '13), Poly stigma rub 



(Blackman 



and Welsford, '12; Nienburg, '14), Gnomonia erythrostoma 

 (Brooks, '10) have failed to furnish any evidence of a real 

 sexual function on the part of either the trichogyne or sper- 

 matia in any of the species of fungi 

 structures. Pairing" 



these two 



Pairing of nuclei in the oogonium, or the pairing 

 of these with nuclei from adjacent cells of the ascogonial 

 branch or archicarp, furnish the synkaria, or the synkaria are 

 organized at different stages in the development of 



hyph 



Note 



In some quarters these 



have led to a loss of confidence in the sexual significance 



of the trichogyne and spermatia of the Ascom 



Some 



have therefore attributed to the trichogyne a physiological 

 significance of another kind, that of a respiratory organ for 



