10 



The North American Cup-Fungi 



celled, later two- or three-celled. At this point one ceases to 

 grow and apparently becomes the antheridium. The other con- 

 tinues to grow imtil it becomes a multicellular archicarp, the 

 end of which tapers into a long slender, multicellular trichogyne 

 which coils itself about and finally fuses with the antheridium 

 (Fig. 5). One of the cells enlarges and becomes the ascogonium. 

 This is similar in all essential details to that recorded for other 

 species of Ascoholus. In this particular case the sex organs are 

 so large that they can be dissected out with fine needles. 



While definite sex organs have been observed in a number 

 of species of operculate cup-fungi and the cytological details 

 worked out in several, a great many are still to be investigated 

 before we can draw^ any general conclusions as to the extent to 

 which these organs are present and actually function. 



4. Ascospore Formation 



After the pairing or fusing of the male and female nuclei 

 in the oogonium the ascogenous hyphae develop from the 



Fig. 6. Beginning of ascus formation, a, basal cell, b, loop cell. 



c, tip cell. 



ascogonium, the paired or fused nuclei passing into the asco- 

 genous hyphae. Just what transpires between the time the 

 nuclei pass into the ascogenous hyphae and the beginning of the 

 formation of the asci from their ultimate branches it is difficult 

 to say since the ascogenous hyphae intertwine in such a manner 

 that it is almost impossible to follow any one through the entire 

 process. The ultimate branch of the ascogenous hypha forms a 

 loop consisting of three cells which might be designated as basal 

 or stalk cell, loop or dome cell, and tip or ultimate cell (Fig. 6). 



