266 TEXT-BOOK OF FUNGI 



weft of much-branched hyphae, certain of the branches 

 becoming transformed into specialised appendages as stated 

 above. This condition of things is met with in the genera 

 Gymnoascus and Ctenomyces. In Arachniotus the peri- 

 thecium is represented by a few simple or slightly branched 

 hyphae, and special appendages are absent. A dense 

 cluster of asci, or free spores, if the asci have disappeared, 

 are located within the primitive perithecium. 



According to Dale, a true sexual mode of reproduction is 

 present. In Gymnoascus Reessii two branches spring up at 

 right angles from a hypha, one on each side of a septum, 

 and twist round one another once or twice. Their free 

 ends become swollen, and each is cut off from its support 

 by a cross-wall. These two cells become closely applied 

 to each other, the walls separating them break down, and 

 the two cells fuse. One of the two fused cells, termed the 

 sterile cell [ = male cell], is usually larger than the other 

 the ascogonium. The latter coils round the sterile cell, 

 becomes septate, and most of the segments give origin to 

 short, thick branches which themselves become branched. 

 These are the ascogenous hyphae, and their tips become 

 swollen and form the minute globose asci. At the time of 

 conjugation both cells contain large numbers of nuclei, and 

 after fusion the protoplasm and nuclei of the two cells 

 become mingled. Doubtless a nuclear fusion now takes 

 place, although this was not determined with certainty. 

 Certain appearances suggest a nuclear fusion in the spores 

 like that occurring in the Uredineae. 



In Gymnoascus setosus the ascospores, on germination, 

 produce one or two germ-tubes which soon branch and 

 give origin to conidia by budding. When these conidia are 

 sown in a hanging drop they begin to produce buds at once, 



