THE FORMATION OF HYPHAL FUSIONS 7 



Sclerotium hydrophilum which he said ' ' give the impression that the 

 hyphae which unite are bent out of their direction of growth and 

 are, so to speak, drawn together as if by the excretion of some 

 stimulating substance." 



In 1892, Reinhardt, 1 in the course of his study of the growth 

 of the hyphae of Sclerotinia sclerotiorum (his Peziza sclerotiorum) , 

 observed and illustrated the formation of fusions in which there 

 was action at a distance. He clearly saw the growth of a younger 

 hypha to the side of an older hypha, the formation of an opposing 

 side-branch (Nebenast), the growth of the younger hypha and of 

 the side-branch toward one another, and the ultimate meeting and 

 fusion of these elements. 



Reinhardt 2 grew different species of fungi together in pairs in 

 the same culture medium and observed the manner in which they 

 influence one another at a distance and in contact in their struggle 

 for existence. Among his observations were the following. Penicil- 

 lium glaucum, by means of excretions, checks the growth of 

 Aspergillus jiavus and A. niger and also stops the growth and causes 

 the death of species of Sclerotinia and of Mucorineae. Aspergillus 

 fiavus and A. niger act on species of Sclerotinia and of Mucorineae 

 like Penicillium glaucum, but not so strongly. Sclerotinia sclero- 

 tiorum attacks and kills the hyphae of Phycomyces nitens, Mucor 

 Mucedo, M. racemosus, Rhizopus nigricans, Acrostalagmus cinna- 

 bar inus and Trichothecium roseum : it winds its hyphae around, and 

 lays the ends of its hyphae upon, the hyphae of its victims, so that 

 they become almost or entirely enveloped in a mycelial sheath. 

 Sclerotinia also lays its hyphae upon the sprout-cells of Dematium 

 pullulans and of Fumago salicina. 



Reinhardt 3 observed that, when a mycelium of Sclerotinia 

 sclerotiorum, and of a Mucor are grown together, the Mucor acts 

 upon the Sclerotinia at a distance (Fig. 2), probably by means of 

 an excretion : it ( 1 ) causes the hyphae of the Sclerotinia to branch 

 in a curious manner and (2) causes many of the branch-hyphae of 



1 M. O. Reinhardt, " Das Wachsthum der Pilzhyphen. Ein Beitrag zur Kenntniss 

 des Flachenwachsthums vegetabilischer 76110161710™^!!," Jahrb. f. wiss. Bot., 

 Bd. XXIII, 1892, pp. 500-502, Taf. XXIII, Fig. 13. 



2 Ibid., pp. 502-519. 3 Ibid., pp. 502-505. 



