SIGNIFICANCE OF CONJUGATE NUCLEI 



271 



diploidisation process increases rapidly as the hyphae of the 

 diploidised mycelium grow in length, owing to the fact that 

 cell-division is preceded by conjugate nuclear division. In the 



Fig. 142. — Coprinus lagopus. Diagram showing two haploid mycelia of opposite 

 sex, (AB) on right (black nuclei), (ab) on left (white nuclei), each derived from 

 a single basidiospore. The two mycelia, as shown in Fig. 141, fused hyphally 

 and formed a fusion cell in which an (AB) nucleus and an (ab) nucleus became 

 associated as a pair of conjugate nuclei. The fusion cell, as here shown, has 

 elongated, branched, and developed into a diploid mycelium characterised by 

 a narrow-angled mode of brafiching, by the presence of a pair of conjugate 

 nuclei in every cell, by conjugate division of the pairs of nuclei accompanied 

 by the formation of clamp-connexions, and by the absence of oidiophores and 

 oidia. On the longest diploid hypha a conjugate nuclear division and the 

 formation of a clamp-connexion is in progress. For the sake of simplicity, 

 only one diploidised ceU and the diploid myceliuna into which it has grown has 

 been represented ; the other cells of the two original haploid mycelia have 

 been left in the haploid state. In reality, the two haploid mycelia would have 

 diploidised one another, and the diploidised terminal cells of all the hyphae 

 of both originally haploid mycelia would have grown out into diploid mycelia 

 like the one shown. The diploid mycelium produced by the mutual diploidisa- 

 tion of the two haploid mycelia would, in the end, produce diploid fruit-bodies, 

 the upper half of one of which in vertical section is represented as discharging 

 spores. Highly magnified. 



diploid mycelium of very many Hymenomycetes, e.g. Coprinus 

 lagopus, each cell-division is accompanied by the formation of a 

 clamp-connexion between the two daughter cells (Figs. 85, p. 155, 

 142, and 146, p. 278). Hence a clamp-connexion is the outward 

 and visible sign of the presence of conjugate nuclei in each of the 

 two cells between which it lies. A diploid mycelium gives rise 



