1915] 



ATKINSON PHYLOGENY IN THE ASCOMYCETES 331 



Now as to the suggested relationship between the phenom- 

 enon of broad or narrow pore formation in the walls of 

 certain cells near the middle or base of the archicarp in 

 certain lichens and other Ascomycetes, and that shown in 

 the communications taking place between the carpogonium 

 and auxiliary cells (often including one or more of the 

 other procarp cells), it may be said (1) that in the red algae 

 this communication of the carpogonium (terminal procarp 

 cell) with other procarp cells when it does take place is not 

 direct, but by a roundabout method, either through a distinct 

 outgrowth from the carpogonium, or through the medium of 

 one or more auxiliary cells, or by a combination of both, to 

 form the central cell; (2) no evidence of any similar round- 

 about method has been observed in the archicarp of the sac 

 fungi. The intercommunication between the middle or basal 

 cells of the archicarp is always direct, and no communication 

 in the multicellular archicarp occurs by means of which either 

 a fertilized nucleus, or a sperm nucleus has been observed to 

 migrate from the terminal cell to the middle or basal cells; 

 (3) that in a number of the fungi where pore formation occurs 

 between cells of the fertile portion of the archicarp, the 

 ' * trichogyne ' ' is either absent, or admittedly degenerate, or the 

 antheridium is absent. Examples are : Ascoholus, studied by 

 Harper ('96), antheridium and trichogyne absent; Asco- 

 phanus carneus, antheridium absent, trichogyne doubtful or 

 degenerate; Lachnea cretea, no antheridium observed, tri- 

 chogyne not functional; Poly stigma rubrum,^ trichogyne not 

 functional, from a multicellular cell at base of archicarp one 

 nucleus migrates into the adjacent uninucleate archicarp cell, 

 which is regarded as the ascogonium (Nienburg, '14). In 

 none of the lichens has a sperm or other nucleus been observed 

 to move down into the fertile part of the archicarp. Pore 

 formation in the archicarp of the Ascomycetes has no phyletic 

 relation to the fusions of auxiliary cells among themselves or 

 with a short ooblastema thread or the egg cell. It occurs in- 



^ Blackman and Welsford ('12), who earlier investigated the cytology of 

 Polystigma rubrum, are of the opinion that the "spermatia" as well as the archi- 

 carps degenerate, and that certain vegetative cells become transformed into as- 

 cogones. 



