HEMIASCOM YCE TES 



151 



directly with the pseudogamous development of Endomyces fibuliger 

 (Fig. 87, 2 to 4). Two cells form a copulation process toward each other 

 (Fig. 93, 1 to 5) the nuclei migrate into the bridge and fuse, the diploid 

 nucleus divides, both daughter nuclei migrate back into copulation 

 cells, there divide a second time, and in each fusion cell two spores arise. 

 The dumbbell structure corresponds to an ascus. In some cases, at 

 least in Z. Priorianus, copulation is absent and the individual sprout 

 cells develop parthenogenetically to asci. Exceptionally, especially 

 in small colonies, if the cultures are transplanted into conditions of 

 nourishment which stimulate them to copulation and spore formation, 



15 16 17 



10 



11 



19 



zo 



m 



ii 



zi 



1* 



Fig. 93. — Zygosaccharomyces Barkeri. 1 to 5 (X650). Dcbaryomyces ghbosus. 

 6 to 14 (X 1,000). Zygosaccharomyces Chevalieri. 15 to 22. (X670). Debaryomyces 

 Kloeckeri. 23 (X 1,000). Copulation and development of asci. (After Barker, 1901; 

 Guillermond, 1912; Guillermond and Peju, 1920.) 



the mother cell, for lack of other cells, will copulate with a daughter cell. 

 Thus, exceptionally, the sexual act may be pedogamous. 



That which was an anomaly in Zygosaccharomyces Priorianus, how- 

 ever, becomes increasingly common in the following forms; simultaneously, 

 copulation, because of the weakening of the sexual tendencies, becomes 

 more and more difficult. Thus, in Debaryomyces globosus from the 

 Antilles, approximately 75 per cent of the asci are parthenogenetic. 

 Occasionally copulation branches are still formed, which for lack of 

 sexual attraction, grow by each other. In about 25 per cent of the 

 cases, a sexual act occurs. This may take place between two mature 

 individuals in which the diploid nucleus either divides in the bridge and 

 returns a daughter nucleus to each fusion cell or withdraws undivided 



