36 



and contrasts this picture with one obtained by inoculating a 

 culture on opposite sides with two doses of the same strain, is 

 fully impressed with the necessity for mating two strains of 

 opposite sex in order to lead to sexual reproduction. 



No ascomycete so far discovered serves better to demon- 

 strate sexual reproduction than Pyronema. The beautiful rose 

 colored ascocarps are frequently seen in places where brush piles 

 have been burned over a few weeks previously. It fruits abun- 

 dantly in petri dish cultures on many kinds of agar media, and 



Figure 1. 

 Monilioid conidia, asexual spores, of Neurospora sitophila. Sporophores 

 branch dichotomously and especially when young show a beautiful symmetry 



the ascospores remain viable for a long time. Numerous oogonia 

 and antheridia which can be readily distinguished are developed 

 in the cultures. One objection to Pyronema is that it does not 

 produce asexual spores and the ascocarps do not show simple 

 striking distinguishing features. Furthermore, the species is 

 haplo-monoecious. Ascoholus magnificus , a species whose asco- 

 carps present a very striking appearance, is heterothallic and 

 develops very large oogonia and antheridia. The ascospores are 

 beautifully colored. It is a very rare species, however, and one 

 not easily cultured. Ascoholus carhonarius is rather common on 

 burned places and develops large sex primordia, but this species 

 also is not readily cultured. 



