THE FUNCTIONS OF HYPHAL FUSIONS i8i 



compound mycelium and are therefore the product of a social 

 organisation. 



The Various Functions of Hyphal Fusions in the Hymeno- 

 mycetes. — Hyphal fusions in the Hymenomycetes are of importance 

 in the five following- ways : (1) they convert every young mycehum 



Fig. 106. — CoUetotrichum trichellum (Ft.) Diike (= Vermicularia 

 trichella Fr. ). To show fusion of germ -tubes or young mycelia 

 derived from two or more conidia. A, two conidia. B, a 

 conidium germinating. C, two young mycelia, derived from 

 two separate conidia c c, which have anastomosed to form a 

 single compound mycelium ; a, an appressorium. D, similar 

 to C, but there is a triangular mesh above and two appressoria 

 a are present. E, three conidia c c c have been connected by 

 hyphal fusions effected by their germ-tubes ; each conidium 

 has sent out a short hypha, the end of which has formed an 

 appressorium a. From original drawings made for the author 

 by Maud M. Duke. Magnification, 608. 



into a network of such a kind that food materials can be conducted 

 through it to fruit-bodies, sclerotia, etc., in diverse directions ; 

 (2) in heterothallic species, they place two mycelia of opposite sex 

 in continuity, thus making possible the association of their nuclei 

 in conjugate pairs ; (3) in heterothallic species, they convert the 

 haploid myceha into a network of such a kind that, when a haploid 

 mycelium is being diploidised by nuclei derived from another 

 haploid mycelium, the nuclei can travel through the mycehum 



