THE FORMATION OF HYPHAL FUSIONS 



65 



audouini, a ring-worm fungus, must have been formed by the simul- 

 taneous outgrowth and subsequent fusing of a pair of pegs. One 

 of these photographs is shown in Fig. 40. The evidence from actual 

 observations of peg-to-peg fusions in Ascomycetes and Basidio- 

 mycetes generally goes to show that the inference as to the nature 

 of bridging hyphae in M. audouini was a correct one. 



Microsporon audouini may possibly be an Ascomycete, but at 

 present it is included in the Fungi Imperfecti. It is very probable 

 that the mode of formation 

 of hyphal fusions in Fungi 

 Imperfecti resembles that ex- 

 hibited by the Higher Fungi 

 as described in this Chapter. 



Critical Remarks on Sup- 

 posed End-to-Side and Side- 

 to-Side Fusions. — In their 

 paper on Microsporon au- 

 douini Davidson, Dowding, 

 and Buller, 1 in respect to the 

 mycelium, say : " From an 

 examination of Text-figs. 10, 

 11, and 12 it appears that all 

 the fusions there illustrated 

 were formed between the end 

 of one hypha and the lateral 

 wall of another hypha. This t}^pe of hyphal fusion has been 

 described and illustrated by Buller." In view of the evidence given 

 in this Chapter that all hyphal fusions in the mycelium of typical 

 Pyrenomycetes, Discomycetes, Hymenomycetes, and Gastromycetes 

 are essentially end-to-end ones, I now feel that there is no support 

 for the view, expressed in Volume IV, 2 that one younger hypha 

 fuses directly with the lateral wall of an older hypha. Rather I am 

 inclined to think that, on the approach of a younger hypha, the older 

 hypha always sends out a longer or shorter peg to meet the younger 



1 A. M. Davidson, E. S. Dowding, and A. H. R. Buller, " Hyphal Fusions in 

 Dermatophytes," Canadian Journal of Research, Vol. VI, 1932, p. 5. 



2 These Researches, Vol. IV, 1931, pp. 152-154. 



VOL. V. F 



Fig. 40. — Microsporon audouini. Mycelium 

 grown in a hanging drop of Sabouraud's 

 medium, ten days after inoculation, 

 showing peg-to-peg fusions between 

 older hyphae. From the paper of 

 Davidson, Dowding, and Buller on 

 Hyphal Fusions in Dermatophytes. 

 Magnification, 250. 



