CLASS ASCOMYCETEAE 



269 



which when separated by the hyphal tip planting are shown to belong to 

 the tw^o different strains. On this mycelium with both kinds of nuclei some 

 branches produce both male and female organs of one phase, self-sterile, 

 and other branches produce similar organs, also self-sterile, but the two 

 sorts are inter-fertile. Thus it is clear that genes for incompatibility are 

 present in the diploid nucleus of the young ascus and during meiosis in 



CULWQC/I 



BUT 



ceossrcKTiLE 

 IN eiTHCK oiHEcrm 



iM TO<}8 



HCRWPHROPITIC UirSTPil.r 



Fig. 89. Sphaeriales, Family Fimetariaceae. Schizo- 

 thecium anserinum (Rabenh). Diagrammatic repre- 

 sentation of the sexual condition. (Courtesy, Ames: 

 Bull. Torrey Botan. Club, 59(6):341-345.) 



the ascus two sorts of nuclei arise, mutually compatible, but self-incom- 

 patible. There is however no segregation of sex as both kinds of nuclei 

 carry the potentiality for the production of male and female organs. 

 (Fig. 89.) 



In the genus Neurospora, as well as in Gelasinospora, Dodge, Shear, 

 Aronescu, Wilcox, and Lindegren (1927-1938) have made an exhaustive 

 study of the sexual reproduction and of the genetics of the segregation of 

 self-incompatibility and mutual compatibility as well as of various other 

 genetic factors. In A'^. sitophila Shear and Dodge and some other species 



