NUMBER OF RADIAL HYPHAE DIPLOIDISED 241 



minutes : (1) No. 5, the fourth branch from the end of the main 

 hypha, which at 1.30 p.m. had been clamp-less, now bore two 

 clamp-connexions as well as a tiny lateral branch also provided 

 with a clamp-connexion ; and (2) No. 6, the third branch from the 

 end of the main hypha, which at 1.30 p.m. had also been clamp-less, 

 now bore three clamp-connexions, while its own two short branches 

 each bore a single clamp-connexion. At 3.40 p.m. there was left 

 to be diploidised only the terminal portion of the main hypha a 

 and the main hypha's two yomigest lateral branches. 



After 3.40 p.m. the terminal part of the main hypha a not yet 

 diploidised produced two more lateral branches, so that it came to 

 have four branches below its apex, Nos. 7-10, still in the haploid 

 condition. The formation of a clamp-connexion on the main hypha 

 a short distance behind its apex and of clamp-connexions on all 

 the four youngest haploid branches of the main hypha was observed 

 between 3.40 p.m. and 5.45 p.m., by the end of which time, therefore, 

 the whole of the main hypha and its branches had become 

 converted from the haploid to the diploid condition (Fig. 133, C). 



A comparison of the drawings A, B, and C in Fig. 133 gives a 

 sufficiently adequate idea of how any leading radial haploid hypha 

 along with its branches, when viewed externally, is converted from 

 the haploid to the diploid state under the influence of nuclei which 

 have come to it from a mycelium of opposite sex. 



Similar observations to those just recorded were made on a 

 large haploid mycelium (AB) when this mycelium was being con- 

 verted into a diploid mycelium by a small diploid inoculum 

 {AB)-\-{ab). We may therefore conclude that the diploidisation of 

 a haploid mycehum, so far as external changes are concerned, is 

 effected by a suitable diploid mycehum in the same manner as by 

 a suitable haploid mycehum. 



The Number of Radial Hyphae of a Large Haploid Mycelium 

 which are converted into Diploid Hyphae through the Action of a 

 Suitable Haploid or Diploid Inoculum. — A small piece of a haploid 

 mycelium, after being set in the middle of a dung-agar plate, grows 

 out radially from its centre ; and, when its periphery is examined, 

 the leading radial hyphae can be readily recognised as such. 



A large haploid mycelium {AB), 6 cm. in diameter (c/. Fig. 124, 



VOL. IV. ^ 



