DIRECTION OF MOVEMENT OF NUCLEI 



10 dcLj a 



233 



Fig. 132. — Coprinus lagopus. Passage of nuclei through the central part 

 of a large haploid mycelium during the diploidisation process. 

 Dimg-agar in the large Petri disli was inoculated in the centre witli 

 a haploid mycelium {AB), and the mycelium grew concentrically for 

 nine days. The rings Nos. 1-9, wliich weie originally made on the 

 base of the Petri-dish with blue pencil, show the daily limits of 

 growth. When the {AB) mycelium had attained the size indicated 

 by the inner heavier circle No. 9, two plano-convex lateral pieces of 

 it, (J and h, together with the dung-agar on which tliey grew, were 

 removed from the Petri dish, so that the (AB) mycelium which 

 remained had the configuration <■ d e f. This band of (AB) myce- 

 lium was then inoculated at one end with a small hyphal inoculum 

 of a haploid mycelium (ab). This inoculum, represented by a black 

 dot, was deposited on the culture medimn on what may be called 

 the zero day. The (AB) and (ab) mycelia soon fused together. 

 Further growth of the mycelia is indicated by the rijigs Nos. 10-19 

 made at the end of each day from the tenth day to the nineteenth 

 day at one end of the central band, and by corresponding rings at 

 the other end. On the ninth day after the inoculum (ab) had been 

 placed upon the plate, clamp-connexions were observed at the places 

 shown by crosses on the ring No. 18, while on the tenth day clamp- 

 connexions were observed all around the ring No. 19. Since clamp- 

 connexions are produced during the division of conjugate nuclei, in 

 this case (AB) and (ab), (ab) nuclei must have travelled through the 

 band of (AB) mycelium c d e f a distance of at least 9-5 cm., as 

 shown by the broken line, in the course of nine days. Drawn by 

 A. H. R. Buller and Ruth Macrae. Two-thirds the natural size. 



