THE FORMATION OF HYPHAL FUSIONS 25 



Kniep * reports that he made a great number of attempts to cross 

 species in the genera Hypholoma, Collybia, and Mycena, but with- 

 out success. Vandendries 2 states that, on pairing haploid mycelia 

 of Panaeolus campanulatus and P. fimicola, he obtained in one 

 instance a mycelium bearing clamp-connexions ; but this mycelium 

 did not grow well and did not fruit, so that it was impossible to 

 obtain analytic evidence of its hybrid origin. From what we know 

 at present it seems probable that, in the Hymenomycetes, hyphal 

 fusions between haploid mycelia of distinct species are formed 

 either not at all or but rarely. 



Investigations by the Author.— Since hyphal fusions are of 

 such common occurrence and of such high functional importance in 

 the Higher Fungi, it seems well worth while to learn all we can about 

 them. As a contribution to our knowledge of hyphal fusions, there- 

 fore, my own observations on the mode in which hyphal fusions are 

 formed in certain representative Ascomycetes and Basidiomycetes 

 will now be recorded. 



Methods and Materials. — The mycelia employed for hyphal- 

 fusion studies were grown in shallow drops of cleared dung-agar 3 

 suspended in van-Tieghem cells. The drops were inoculated either 

 with spores or with pieces of mycelium removed from stock plate 

 cultures. The species chiefly used for observation were six in 

 number and they are classified in the following list. 



List of Fungi used in Hyphal Fusion Studies 



'Pleurage curvicolla 



Ascomycetes 



Pyrenomycetes i Pleurage anserina 



iFimetaria (Podospora) fimicola 

 ^Discomycetes . Pyronema confluens 



ifCoprinus sterquilinus 

 Hymenomycetes i~ . , 

 ( Copnnus lagopus 

 C4astromycetes . Sphaerobolus stellatus 



Heft V, 1924, p. 145. Among the crosses which Brunswik tried were : C. niveus X 

 C. fimetarius ; C. niveus X C. Friesii ; C. lagopus (not the C. lagopus of these 

 volumes) X G. fimetarius ; and C. ephemerus X C. curtus. 



1 H. Kniep, Die Sexualitat der niederen Pflanzen, Jena, 1928, p. 411. 



2 R. Vandendries, " Recherches sur le determinisme sexuel des Basidiomycetes, 

 Mem. Acad. Belg., CI. des Sci., S6r. 2, T. V, 1923, p. 98. 



3 Details of the preparation of cleared dung-agar are given in these Researches, 

 Vol. IV, pp. 195-197. 



