4 o RESEARCHES ON FUNGI 



where clamp-connexions exist in a diploid mycelium, they serve to 

 facilitate the translocation of protoplasm from cell to cell and, in 

 particular, from the vegetative diploid mycelium as a whole either 

 directly into a fruit-body or into such temporary storage organs as 

 sclerotia or mycelial cords which are destined eventually to produce 

 fruit -bodies. 



Where clamp-connexions occur in hymenomycetous fruit-bodies, 

 e.g. in those of Armillaria mucida, 1 Corticium petrophilum, 2 and 

 Peniophora clavigera, 3 they doubtless serve to facilitate the passage 

 of protoplasm through the fruit-body tissues and into the basidia 

 and other hymenial elements. 



Clamp-connexions and the Hooks of Ascogenous Hyphae. 

 The hooks produced by ascogenous hyphae in Pyronema confluens 

 (Fig. 20) and certain other Discomycetes 4 have been regarded by 

 Mile Bensaude, 5 Kniep, 6 and Gaumann 7 as homologous with the 

 clamp-connexions of the Hymenomycetes ; but between hooks and 

 clamp-connexions there are important differences, which may be 

 summarised as follows : (1) whereas clamp-connexions occur in 

 series along the hyphae of a vegetative mycelium, hooks occur not 

 in a vegetative mycelium but in the terminal branches of ascogenous 

 hyphae ; (2) whereas a clamp-connexion is formed in the middle of 

 a terminal cell of a hypha, a hook is formed at the extreme end of 

 a terminal cell of a hypha ; (3) whereas in a clamp-connexion the 

 cell in which a single nucleus is temporarily imprisoned is formed 

 from a lateral branch of the main hypha, in a hook the corresponding 

 cell is cut off from the end of the main hypha after this has become 

 bent backwards at its apex ; and (4) whereas clamp-connexions 



1 Vide H. Kniep's illustration in Strasburger's Text-book of Botany, English ed. 

 No. 6, London, 1930, Fig. 413, p. 458. 



2 H. Bourdot and A. Galzin, Hymenomycetes de France, 1927, Fig. 70, p. 230. 



3 Ibid., Fig. 78, p. 280. 



4 Not all Discomycetes develop hooks at the ends of their ascogenous hyphae. 

 Among discomycetous species in which the asci are formed from binucleate 

 ascogenous cells, no hooks being formed, are : Geopyxis catinus (Guillermond, 1905) ; 

 and Plicaria succosa and Acetabula leucomelas (Maire, 1905). Vide Gaumann and 

 Dodge, Comparative Morphology of Fungi, 1928, p. 131. 



5 Mathilde Bensaude, Recherches sur le cycle evolutif et la sexualite chez les 

 Basidiomycetes, Nemours, 1918, pp. 117-123. 



6 Hans Kniep, Die Sexualitat der niederen Pflanzen, Jena, 1928, pp. 392-393. 



7 E. Gaumann, Vergleichende Morphologic der Pike, Jena, 1926, pp. 399-400. 



