228 RESEARCHES ON FUNGI 



a septum, cause the cytoplasm in contact with the septum to break 

 this barrier down or in some way to open a passage through it or 

 round it. Lehfeldt,i working with Typhula erythropus, actually 

 observed in a mycehum which was becoming diploidised a number 

 of walls which had been dissolved on one side and reduced to " three- 

 quarter " or " half " walls, 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. 



It may well be that, in Coprinus lagopus, just as in Typhula 

 erythropus, the septa of a haploid mycelium which is being diploidised 

 break down partially or completely before an advancing nucleus of 

 opposite sex ; but this supposition remains to be verified or refuted 

 by further observations. 



(8) Concluding remarks on nuclear movement. The cause of the 

 movement of a nucleus of one sex, say {ab), through a haploid 

 myceUum of another sex, say {AB), is at present a profound mystery. 

 Obviously, in the supposed particular case, when diploidisation is in 

 progress, the {ah) nuclei keep moving away from the diploidised 

 part of the {AB) mycelium into the non- diploidised part where, 

 dividing as they go, they finally enter every vigorously-elongating 

 hypha. One must suppose that there is a distinct physiological 

 difference between the already-diploidised and the not-yet-diploidised 

 parts of any mycelium in process of diploidisation or there would 

 be no movement of nuclei from one to the other. Does the difference 

 lie in the cytoplasm only, the nuclei only, or in cytoplasm and nuclei 

 combined ; and what is the nature of the difference ? To these 

 questions at present we can give no answer. 



When, in regarding a large haploid myceUum of Coprinus 

 lagopus which is becoming diploidised, we take into consideration 

 its irregularly-netted structure, the thinness of its hyphae, the 

 numerous septa which divide the hyphae into separate cells, and 



1 W. Lehfeldt, loc. cit., p. 14. 



