THE FORMATION OF HYPHAL FUSIONS 



63 



three hours elapsed between the first and last stages represented in 

 Fig. 37. 



From the observations just recorded, it is obvious that the hyphal 

 fusion phenomena of Coprinus lagopus resemble those of C. sterqui- 

 linus, Pleurage curvicolla, P. anserina, and Pyronema confiuens. 



Sphaerobolus stellatus. — Sphaerobolus stellatus, whose fruit-bodies 

 are described in a later chapter of this volume, is a typical Gastromy- 

 cete. Its mycelium was obtained by sowing a gleba, shot on to a 

 sterilised slide, in sterilised horse dung. The mycelium exhibits 



Fig. 38. — Sphaerobolus stellatus. Four stages in the formation of a hypha-to-peg 

 fusion. A : the hypha a, which bears two clamp-connexions seen in lateral 

 view, has given rise to a branch-hypha b which bears a clamp-connexion seen 

 in face view. The hypha b by chance is approaching c obliquely. B : the 

 hypha b has approached nearer to c and has stimulated c morphogenically so 

 that c has sent out a peg opposite to the end of b. C : the hypha and the peg 

 grew as though they would pass one another and then, as a result of mutual 

 tropic stimulation, made growth-curvatures through a right angle, so that their 

 ends have now met. D : the hypha b and the peg have now completely fused 

 with one another. Owing to the exhaustion of the medium, the hypha b grew 

 very slowly in length and three hours elapsed between stage A and stage D. 

 Magnification, 430. 



numerous hyphal fusions of all types, and three fusions are shown 

 incidentally in the mycelium illustrated in Fig. 144, p. 291. 



A hanging drop of sterilised dung-agar was inoculated with a tiny 

 piece of mycelium taken from a stock culture and, on the next day, 

 hyphal fusions were being formed in considerable numbers. 



By continuous watching of particular parts of a mycelium, with 

 the help of Dr. Dowding I succeeded in observing successive stages 

 in the production of an undoubted hypha-to-peg fusion and of 

 another fusion which I prefer to interpret as a hypha-to-peg fusion, 

 although it may possibly have been a peg-to-peg fusion. 



In the hypha-to-peg fusion, a lateral hypha bearing a clamp- 

 connexion was seen approaching the side of an older hypha 

 (Fig. 38, A). The older hypha sent out a peg (B) ; the lateral hypha 



