1915] 



ATKINSON — PHYLOGENY IN THE ASCOMYCETES 



327 



1. The simplest type of cystocarp development 

 the Nemalionales where the carpogonium 

 fertilization. 



after 



gives rise to 



eral branched sporogenous 



threads in a compact cluster, bearing terminally the 



sjjores (Nemalion, Lem- 



anea, etc.), or in some 



species the sporogenous 



threads are more widely 



extended in the thallus, 



the branches producing 



separated clusters o f 



carpospores (Dermo- 



nema dichotomum. see 



Fig. 5. A and B, Lemanea; C, Batrachosper- 

 mum: cpbr, procarp or carpogonial branch; 



trichogy 



sp 



Schmitz 

 fleisch. 



97) 



d Haupt 

 Fertiliza 



cpg, carpogonium or egg; ir, 



spermatium; g, gonimoblast; csp, carpospores. 



— A and B, after Atkinson; C, after Davis. 



tion by the fusion of a sperm nucleus with the egg nucleus 

 after entrance into the trichogyne and migration down intc 

 the carpogonium has been described in Nemalion (Wolfe, '04) 

 and in Bat rachospermum (Schmidle, '99; Osterhout, '00) 



2. In 



(Rhodo 



the Drocarn branch 



of four cells is curved around so that the carpogonium is in 

 contact with an auxiliary cell lying between the carpogonium 

 and the pericentral cell which gave rise to the procarp. After 

 fusion of the sperm and egg nucleus in the carpogonium, the 

 fusion nucleus divides once, 

 with the auxiliarv cell mentioned, which fuses with 



The carpogonium now 



central cell. The two diploid 



migrate 



the peri- 



central cell, the carpogonium separates from the auxiliary cell, 

 while it and the remaining cells of the procarp degenerate. The 

 pericentral cell now fuses with several o 

 which arose from it as a branch, forming t] 

 diploid nuclei remain in the upper part 



The 



of 



central 



while the haploid nuclei from the auxiliary cells, some 

 divided, now degenerate (Yamanouchi, '06 ). 



3. A somewhat different situation exists in ErytJ 

 phyllum delesseroides (Gigartinales). The ooblastema fila 

 ment from the fertilized egg connects with the auxiliary eel 

 which is the basal cell of the seven or e 



ght- celled 



pro- 



