166 RESEARCHES ON FUNGI 



in R. solani, it was found that protoplasm flows through the pore 

 of a bulged septum toward the hypha's growing point. 



The Passage of Nuclei throug-h the Haploid Mycelium of 

 Hymenomycetes during the Diploidisation Process. — In Volume IV 

 of this work, I showed that, in Coprinus lagopus, when a large 

 haploid mycelium 6 cm. in diameter is becoming diploidised by a 

 small haploid mycelium of opposite sex, nuclei pass out of the small 

 mycelium and through the large mycelium from one side to the 

 other in the course of three or four days. 1 Since such a large 

 mycelium has its hyphae divided up into cells by thousands of 

 septa, this question arises : how do nuclei of opposite sex pass 

 from cell to cell along the hyphae which they are diploidising ? 

 To consider a concrete case, let us suppose that the haploid mycelium 

 becoming diploidised is (AB) and that the nuclei diploidising its 

 hyphae have come from a haploid mycelium (ab). Then our 

 problem is : how do (ab) nuclei pass from cell to cell along the 

 (AB) hyphae ? 



Lehfeldt, 2 as a result of a cytological investigation upon Tyj)hula 

 eryihropus, states that, in a haploid mycelium that was becoming 

 diploidised, he observed a number of septa which had been dissolved 

 on one side and reduced to " three-quarter " or " half " septa, thus 

 permitting nuclei to pass through them ; and, in his Text-fig. 1 a, 

 he shows individual nuclei drawn-out and, as it were, in the act of 

 threading themselves through the hole in a partially-dissolved 

 septum. He also states that the lateral wall of a hypha at the side 

 of a partially-dissolved septum was sometimes bulged outwards 

 slightly, as if to increase the width of the septal opening and thus 

 to facilitate the movement of a nucleus when passing through it. 



If Lehfeldt's observations were correctly made, the answer to 

 our question concerning the diploidisation of an (AB) mycelium 

 of Coprinus lagopus by (ab) nuclei would be as follows. An (ab) 

 nucleus, on approaching a septum in an (AB) hypha, in some way 

 causes the septum to break down partially or causes the (AB) 

 hypha to bulge and so leave a space between the septum and the 



1 These Researches, Vol. IV, 1931, pp. 213-229. 



2 W. Lehfeldt, " Uber die Entstehung des Paarkernmyzels bei heterothallischen 

 Basidiorayceten," Hedwigia, Bd. LXIV, 1923, pp. 13-51. 



