278 



RESEARCHES ON FUNGI 



r\ 



a pair of conjugate nuclei {AB)-^{ab) becomes established in a 

 cell next to another cell, either older or younger, which contains 

 only an (ab) nucleus and therefore is still haploid, the (AB) nucleus 



of the conjugate pair 

 divides and one of the 

 daughter {AB) nuclei 

 wanders into the haploid 

 cell, associates itself with 

 the (ab) nucleus there 

 present, and so takes part 

 in the formation of a 

 second conjugate pair of 

 nuclei {AB)-\-{ab). 



Thus, through the 

 agency of a single initial 

 (AB) nucleus, our large (ab) 

 mycelium, which when it 

 fused with the (AB) hj-pha 

 contained 100,000 nuclei, 

 becomes diiDloidised as a 

 whole. 



Assuming that the 

 essential features of the 

 diploidisation process as it 

 goes on in a hymenomy- 

 cetous haploid mycelium 

 have been correctly indi- 

 cated in the description 

 of the conversion of a 

 large haploid mycelium 

 (ab) into a diploid myce- 

 lium {AB)-}-{ab) as just 

 given, we must conclude that, in general, the diploidisation pro- 

 cess in the Hymenomycetes is dependent on the formation of 

 conjugate nuclei (n)+(n) and on the avoidance of the formation 

 of isolated {2n) nuclei. The formation of conjugate pairs of nuclei 

 permits one of each pair to divide independently of its fellow 



Fig. 146. — Coprinuslagopus. Diagram to show 

 how a haploid hypha after it has just been 

 diploidised develops further. No. 1 : a 

 haploid hypha (ah) or (AB) which has just 

 been converted into a diploid hypha 

 (AB)-\-(ah) ; a pair of conjugate nuclei is 

 present in each cell. No. 2 : the cells d and 

 e have branched and the cell c has elon- 

 gated ; in / a hook has grown backwards ; 

 in g an (AB) nucleus has passed into tlie 

 hook ; in the terminal cell c the two nuclei 

 are dividing conjugately and the hook is 

 growing toward the main hypha. No. 3 : 

 in the branch / the two daughter pairs of 

 conjugate nuclei have separated from one 

 another and two septa s have been fonned, 

 but the lower (AB) nucleus is momentarily 

 a prisoner in the hook-cell h from which it 

 will escape as soon as the walls at p have 

 broken down ; in the branch g and the 

 terminal cell c conjugate nuclear division 

 and cell-division with the formation of a 

 clamp-connexion have been completed, and 

 each daughter-cell contains a pair of con- 

 jugate nuclei (AB) and (ab). Highly mag- 

 nified. 



