1915] 



ATKINSON PHYLOGENY IN THE ASCOMYCBTES 



329 



sterna filament after fusing with one auxiliary cell may grow 

 forward and fuse with another and so on. The diploid nucleus 

 formed in the egg multiplies by division in the ooblastema 

 filaments. In the fusion cell, resulting from the union of the 

 filament and auxiliary cell, the diploid and haploid nuclei repel 

 each other so that the former lies on the filament side while 

 the latter lies in the base of the auxiliary cell. An outgrowth 



Fig. 7. Dudresnaya purpurifera: A, ooblastema filaments fusing with 

 auxiliary cells; B, C and D, outgrowth from the fusion cell to form the 

 central cell; C, diploid nucleus dividing; D, central cell of cystocarp separated 

 by a wall. Note that the nucleus of the auxiliary cell remains distant from 

 the diploid nucleus of the ooblastema filament. Shaded portions are diploid. 

 cphr, carpogenic branch; cpg, carpogonium; tr, trichogyne; of, ooblastema 

 filament; fc, fusion cell; ac, auxiliary cell; an, auxiliary cell nucleus; cy, 

 central cell of cystocarp. — After Oltmanns. 



arises from the ooblastema filament at the point where the 

 diploid nucleus lies. The latter divides, one nucleus migrat- 

 ing into the outgrowth, while a wall separates it from the 

 fusion cell. This new cell with its diploid nucleus becomes 

 the central cell (Oltmanns, '04). 



7. In Cruoriopsis cruciata the situation is similar. The 

 ooblastema filament by coursing widely through the thallus, 

 fuses with the terminal cell (auxiliary cell) of ''secondary 

 procarp branches." Each of these fusion cells, or auxiliary 

 cells, then gives rise to one or two simple rows of 2-4: spores 

 (Schmitz, 79, '83), or a single 2-4-celled spore chain (Olt- 

 manns, '04). 



