94 



MYCOLOGY 



thallic species are all homogamic, that is, there is no difference in the 

 size of the two gametes which conjugate. This group includes such 



Fig. 28. — Zygospore formation in Sporodinia grandis from material growing on toad- 

 stool. (Slide prepared by H. H. York, Cold Spring Harbor, July 29, 1915.) 



)H*^( 



V==«of 



f=^^x^/ // 



Fig. 29. — Conjugation and development of zygospores between + and — races of 

 black mould, Rkizopus nigricans. 



fungi as A hsidia carulea, Mucor mucedo, and five other forms of Mucor. 

 Phycomyces nilens and Rhizopus nigricans (Fig. 29). Taking the con- 



