14 
E. M. Cutting 
the spores of which give rise some to + and some to — mycelia. 
This causes Edgerton to regard the formation of perithecia at the 
junction of + and — mycelia as being consequent on a sexual act. 
We are, however, quite ignorant of the method of origin and develop¬ 
ment of the ascocarp in this form and it is to be hoped that some 
information on this subject will soon be forthcoming. Shear and 
Miss Wood ( 39 ) have investigated this Glomerella and are of the opinion 
that hybrids are formed. Edgerton, as already mentioned, finds 
himself unable to accept this view. A side issue, but an important 
one, is to be found in the fact that this fungus is a parasite and the 
presence of both strains in a district would probably cause a larger 
spore-formation and so indirectly lead to greater destruction than 
if one form only were present. It will be seen that, whatever the 
cytological examination of these forms may result in, the case of 
Glomerella differs from all those so far described in that both its 
strains can form ascal-producing fruits; the result of the presence of 
both being that a greater number of ascocarps than usual are produced. 
A case which, in a way, seems to resemble this, has lately been 
shortly described by Taubenhaus( 42 ). In Sclerotium rolfsii there were 
indications of the formation of abundant sclerotia when certain 
kinds of mycelia met, these sclerotia differed in no ascertainable 
way from the sclerotia formed on any other mycelium and we might 
regard the phenomena here exhibited as being due to an interruption 
of vegetative growth, as in the case of oospores in Phytophthora 
erythro-septica, described by Murphy ( 35 ), were it not that Taubenhaus 
does not get the phenomena to take place at the point of contact of 
any kind of mycelial growth. This worker was unfortunate enough 
to have his cultures destroyed, by mistake, when he was away at 
war-work, and was unable to follow the matter any further on his 
return. It will be difficult to get an explanation of this behaviour, 
i.e. the abundant formation of, presumably, vegetative resting bodies, 
which will also include the other cases mentioned above. 
In various other Ascomycetes, e.g. in Diaporthe Batatatisffl) and 
in Gibberella Saubinetii (Dickson and Johann ( 19 )) various strains 
have been recorded, and in the Basidiomycetes considerable diffi¬ 
culties have been encountered in bringing them into fruiting stages. 
In these cases, where external conditions are not the factors con¬ 
cerned, as well as in the Fungi imperfecti, the observations of Miss 
Bensaude and of Edgerton point to a new manner of tackling the 
problem of obtaining the higher fructifications. 
University College, London, October 1920. 
