THE FORMATION OF HYPHAL FUSIONS 17 



that chemomorphic influences are exerted by the fusion hyphae, 

 which come to expression in that these hyphae stimulate a neigh- 

 bouring hypha or cell to send out a fusion-branch." 



In his investigations on Leptosphaeria Coniothyrium and Monilia 

 fructigena Laibach l noticed that in water and in weak nutrient 

 media hyphal fusions are far more frequent than in strong nutrient 

 media and that fusion-formation begins when the rate of growth of 

 the germ-tubes begins to slow down. He 2 also observed that, when 

 conidia of Monilia fructigena are germinated in a film of apple-juice 

 between a slide and a cover-glass, the germ-tubes of the conidia 

 near the edge of the cover-glass grow toward the middle of the 

 cover-glass and never show any inclination to form anastomoses 

 with one another, and he concluded that in this phenomenon an 

 important part is played by the pressure of oxygen. 



In 1929, Kohler, 3 as a result of watching the formation of fusions 

 between hyphae in the mycelium of Sclerotium solani, Sclerotinia 

 fructigena, and Hypochnus (Bhizoctonia) solani, confirmed Marshall 

 Ward's observations on action-at-a-distance between hyphae about 

 to fuse and, with the exception of clamp-connexion fusions, he 

 observed and illustrated fusions corresponding to all those types 

 which I myself have observed and which will shortly be described 

 and classified. 



Kohler 4 also suggested that the terms telemorphosis and zygo- 

 tropism which Burgeff s had employed in his analysis of the " attrac- 

 tive processes " concerned in the conjugation of certain Mucorineae 

 should be employed for the essentially similar " attractive processes ' : 

 which take place in connexion with hyphal fusions in the Higher 

 Fungi. Thus he would use the term telemorphosis for the pheno- 

 menon in which one hypha, acting at a distance, stimulates another 

 hypha to alter its form by sending out an opposing fusion hypha ; 

 and he would designate as zygotropism the phenomenon in which 



1 F. Laibach, loc. tit., pp. 348-349, 352-353. 



2 Ibid., pp. 253-356. 



3 E. Kohler, " Beitrage zur Kenntnis der vegetativen Anastomosen der Pilze, 

 I.," Planta, Bd. VIII, 1929, pp. 140-153. 



4 Loc. tit., p. 153. 



5 H. Burgeff, " Untersuchungen liber Sexualitat und Parasitismus bei Mucorineen. 

 I.,' 1 Goebers Botanische Abhandlungen, Heft IV, 1924, pp. 12-14. 



vol. v. o 



