292 RESEARCHES ON FUNGI 



way through one of the trichogynes into the subjacent ascogonium, 

 and let us suppose that this ascogonium contains two hundred 

 female nuclei. On coming into the ascogonium the one hundred 

 male nuclei would be attracted to the female nuclei, but would be 

 inhibited from fusing with them. Hence, if none of the nuclei under- 

 went division, one hundred pairs of conjugate nuclei would be 

 formed and one hundred female nuclei would be left without mates. 

 However, since the one hundred male nuclei in the one hundred 

 conjugate pairs of nuclei have not fused with their mates but have 

 retained their identity, there is the possibility that any male nucleus 

 of a conjugate pair that happened to be situated near an unpaired 

 female nucleus might receive a stimulus from that nucleus, divide, 

 and so provide an extra male nucleus that might pass to the 

 unpaired female nucleus and so provide it with a mate. In this 

 way it is conceivable that most or all of the one hundred female 

 nuclei for which at first there were no male mates might come to 

 have mates in the end. Similarly, if more male nuclei entered an 

 ascogonium than there were female nuclei there, some of the female 

 nuclei in the conjugate pairs might divide and so supply the 

 unmated male nuclei with their appropriate mates. 



Assuming that the diploidisation process takes place in the 

 ascogonia of Pyronema confiuens in the way that has been suggested, 

 it is clear that an essential factor in its operation is that two nuclei 

 of opposite sex, on coming together, do not fuse and form isolated 

 (2w.) nuclei but remain associated as a pair of conjugate nuclei 

 (w)-f (n), thus permitting every member of a pair of conjugate 

 nuclei to retain its identity, so that it can divide independently of 

 its fellow member whenever such a division will promote the 

 diploidisation process. 



The same inhibition that prevents two nuclei of opposite sex 

 fusing in the ascogonium prevents them fusing in the ascogenous 

 hyphae, where conjugate nuclear division takes place until the 

 ascus cells are formed. 



Enough has been said by way of suggestion as to how the 

 organisation of the nuclei of Pyrenomycetes and Discomycetes as 

 conjugate pairs (r?) + (w) instead of as isolated nuclei (2^0 may be 

 of importance during the diploidisation process. It will be of 



