THE FORMATION OF HYPHAL FUSIONS 



61 



a number of hypha-to-hypha fusions had taken place within it. 



Among the numerous hyphal 



fusions which an older mycelium 



displays, it is not difficult to find 



plenty of examples of all three 



kinds : hypha-to-hypha, hypha- 



to-peg, and peg-to-peg. 



It is clear that in Coprinus 

 sterquilinus, a typical Hymeno- 

 mycete, just as in the Pyreno- 

 mycetes and the Discomycetes, all 

 the hyphal fusions are essentially 

 end-to-end ones. 



Coprinus lagopus. — Coprinus 

 lagopus, often called C. fimetarius, 

 is a common horse-dung Hy- 



menomycete. Its fruit-bodies were described in Volume III 

 and its sexual processes in Volume IV. The mycelium produces 



Fig. 35. — Coprinus sterquilinus. Two 

 stages in the formation of a peg- 

 to-peg fusion. A, two opposing 

 pegs are growing toward one 

 another. B, a few minutes later ; 

 the pegs have met and fused ; the 

 end of one peg lies over the other 

 and the fusion plane is parallel 

 to the plane of the paper. Magni- 

 fication, 434. 



Fig. 36. — Coprinus lagopus. Three stages in the formation of a hypha-to- 

 hypha fusion. The mycelium, derived from spores sown two days pre- 

 viously, is haploid and so does not bear clamp-connexions. A : two 

 hyphae, a and b, which came into existence and grew for some time 

 independently of one another, happen to have approached one another, 

 and now their ends are stimulating and growing toward one another. B, 

 a few minutes later than A : the ends of the two hyphae have met. C, a 

 few minutes later than B : the hyphae a and b have fused end-to-end. 

 At d in A can be seen two opposing pegs put out by the hyphae b and c. 

 These pegs may have fused later than at the stage C, but were not 

 observed to do so. Magnification, about 434. 



many hyphal fusions, especially under starvation conditions. 

 A mycelial network formed by fusions between the hyphae of 



