140 



MEDICAL MYCOLOGY 



In Endomycopsis fihuliger, although any two cells may form copulation 

 branches which approach each other, even with the dissolution of the wall 

 the 2 nuclei rarely fuse {Fig. 20, 1). Generally the copulation branches de- 

 velop parthenogenetically, though the separating walls may be temporarily 

 dissolved. In exceptional cases there may occur a pseudogamous anastomosis 

 of two sprout cells, one changing to an ascus. (Fig. 20^ 2-4). 



In a large number of cases no copulation branches are formed, but the 

 asci, like the sprout cells, arise as lateral outgrowths of the hyphal cells 

 (Fig. 20, 6). These asci are three or four times larger than the ordinary 

 sprout cells. Occasionally, they arise from ordinary swollen hyphal cells, 

 or from swollen sprout cells. When they begin to appear, the formation 

 of sprout cells slows up, but does not cease, with the result that hyphae may 

 form sprout cells and asci simultaneously. One finds even young asci which 

 continue to cut off sprout cells until the beginning of spore formation. Periods 



Fig-. 20. — Endomycopsis fihuliger. Development of asci. (XoOO.) (After Guilliermond 1909.) 



of vegetative growth and fructification are thus not sharply differentiated 

 one from the other. Each ascus contains four cucullate spores. At germina- 

 tion, these throw off the exospore and germinate either with a germ tube or 

 with a sprout mycelium. Here sexuality is so completely weakened that only 

 vestiges of the sexual organs remain. In a large number of cases where no 

 copulation branches are formed, the asci arise directly from vegetative hyphae 

 or sprout cells. 



In the remaining forms of the isogamous series, copulation branches de- 

 velop less frequently and the asci arise parthenogenetically without fusion. 

 Growth of mycelium by sprouting increases proportionally. In two Chinese 

 species, E. Lindneri and E. Hordei, the copulation branch no longer changes 

 directly to an ascus but develops to a short, occasionally branched mycelium 

 where asci arise by swelling of the hyphal cells (Fig. 21, 1, 2) . In most cases 

 the asci are formed directly from the sprout cells without this detour. 



