122 



ASCOMYCETES AND RHODOPHYCE^. 



of contact dissolve, the cytoplasm of the two cells becomes continuous. 

 The nuclei show no tendency even to approach each other, but, on 

 the contrary, that of the cell of the sporogenous filament seems to 

 repel the nucleus of the auxiliary cell, as this one generally retreats 

 from its former central position to the side farthest removed from the 

 point of contact of the two cells (Fig. 47, E, and Fig. 48, A). That 

 part, or half, of the fusion cell which corresponds to the sporogenous 

 filament now begins to send out a protuberance into which the sporoge- 



sJC 



sIC 



; c 



D 



FIG. 48. Copulation of sporogenous filaments with auxiliary 

 cells, and origin of a cystocarp in D. purfurifera. (After 

 Oltmanns.) 



A, a sporogenous filament has fused near its end with an aux- 



iliary cell; sK, sporogenous nucleus, az, auxiliary cell. 



B, sporogenous filament after copulating with an auxiliary cell 



has continued its development; protuberance containing 

 sporogenous nucleus, sK, will probably give rise to a cys- 

 tocarp ; aK, nucleus of auxiliary cell. 



C, a sporogenous cell has been cut off from the filament oppo- 



site point of fusion with an auxiliary cell ; sK, sporogenous 

 nucleus ; aK, nucleus of auxiliary cell. 

 D, later stage; sp, a very young cystocarp. 



nous nucleus and dense cytoplasm pass (Fig. 47, E, sz). In the 

 earlier developmental stages following fecundation this protuberance 

 develops an additional branch of the sporogenous filament which is 

 to seek and fuse with other auxiliary cells (Fig. 48, A, B). In case 

 of the development of a cystocarp from the fusion cell, the protube- 

 rance in question, after the division of its nucleus, will be cut off as a 

 rounded cell (Fig. 48, C), which will give rise ultimately to a spore 

 fruit. 



In Dudresnya purpurifera the nuclei of auxiliary cells which 

 have fused with cells of the sporogenous filaments tend to diminish in 

 size and disappear, while in D. coccinea the nucleus of the auxiliary 

 cell may remain normal and divide. In no case, however, do these 

 auxiliary nuclei show any disposition to fuse with a sporogenous 

 nucleus. 



