THE FORMATION OF HYPHAL FUSIONS 59 



I observed a peg-to-peg fusion in which three pegs were involved. 

 By a mechanical operation with a needle a branch -hypha was 

 brought more or less parallel to the larger hypha from which it had 

 developed. Four peg-to-peg fusions were then formed one after 

 another between the two hyphae. The third peg-to-peg fusion is 

 shown in Fig. 33, A. The fourth peg-to-peg fusion was initiated 

 by the outgrowth of a single peg from the larger hypha and two pegs 

 from the opposing smaller hypha (Fig. 33, B). The single peg grew 

 toward the smaller of the pair of pegs, touched it (C), and fused 

 with it (D). The remaining peg became bent toward the single peg 

 but ceased to grow after the fusion of the two other pegs had been 

 accomplished. The time which elapsed between stage B and stage D 

 was 29 minutes. The distance between the hyphae at the point 

 where these gave rise to opposing pegs was about 14 y.. 



Bridging hyphae in Pyronema confluens, each formed by the 

 union of two short pegs, not infrequently come into existence where 

 two hyphae cross one another. One such bridging hypha which 

 connected two monosporous mycelia is seen in the next Chapter in 

 Fig. 65 at c (p. 120). 



Hypha-to-hypha fusions in Pyronema confluens are often formed 

 intrahyphally after a single cell, or two or more adjacent cells, in 

 a hypha have been killed or have died. The formation of such 

 fusions will be described in the next Chapter. 



The observations made on the living mycelium of Pyronema 

 confluens warrant the conclusion that the hyphal fusions in this 

 Discomycete resemble in their mode of formation those of the 

 Pyrenomy cetes . 



Coprinus sterquilinus. — Coprinus sterquilinus is a Hymenomycete 

 with large fruit-bodies. 1 Its mycelium forms numerous hyphal 

 fusions (cf. Vol. IV, Fig. 89, p. 159). In Volume IV their function 

 was discussed in detail. 



Hanging drops of cleared dung-agar were inoculated with 

 mycelium one day, and hyphal fusions were observed forming in the 

 drop the next day. 



By continuous watching of particular parts of a mycelium I 



1 For illustrations, vide these Researches, Vol. Ill, 1924, pp. 180-236, and Vol. IV, 

 1931, pp. 95-98. 



