ORDER SACCHAROMYCETALES 



339 



lateral conidia. The asci are elongated and many-spored. They open at 

 the apex and the ascospores escape, sometimes in a worm-like mass. 



Dipodascus alhidus Lag. was found growing in the gummy exudate 

 of the cut surface of a tropical species of Bromeliaceae. Its septate 

 mycelium consists of multinucleate cells. From two adjacent cells in a 

 hypha arise multinucleate branches which come into contact and fuse 

 at their tips. These branches are then separated from the main hypha by 

 septa. At the tips of each of the gametangia a single "privileged" nucleus 

 enlarges and these two unite in or near the passageway formed by the 



Fig. 110. Saccharomyce- 

 tales, Family Ascoideaceae. 

 Dipodascus uninucleatus 

 Biggs. Stages in sexual re- 

 production. (A) Early stage 

 in conjugation of adjacent 

 cells. (B) Zygote cell en- 

 larged and nuclei united, 

 thus forming primordium of 

 ascus. (C) Young ascus in 

 4-nucleate stage. (D) Young 

 ascus with 16 nuclei. (E) 

 Mature ascus. (After Biggs: 

 Mycologia, 29(l):34-44.) 



dissolution of the intervening walls. From this region grows upward the 

 somewhat tapering ascus into which pass not only the cytoplasm of the 

 gametangia but also their many nuclei and the larger zygote nucleus. 

 The latter divides, apparently meiotically, and probably the four nuclei 

 thus produced continue to divide. It is assumed that it is the nuclei thus 

 formed that serve as the centers about which the ascospores are produced. 

 There are many degenerating nuclei in the ascus which may be the original 

 haploid nuclei introduced from the gametangia. Eventually the apex of 

 the ascus dissolves and the ellipsoidal ascospores escape in a gummy 

 mass. The vegetative hyphae reproduce asexually by the formation of 

 oidia. In D. uninucleatus Biggs it was shown by Miss Biggs (1937) that 

 the cells of the mycelium and the gametangia are uninucleate. As a result 



