NOTES 
ON THE PRESENCE OF BINUCLEATE CELLS IN THE ASCOMYCETES. 
Some time ago I indicated, from a morphological standpoint, the origin of the 
Protobasidiomycetes and the Basidiomycetes from conidial forms of the Ascomy- 
cetes \ 
In a criticism on this paper Harper 2 remarks as follows : — 
1 The widespread occurrence of regularly binucleate cells in the Basidiomycetes, 
with the additional evidence that these cells reproduce by conjugate division and 
constitute the reproductive series (Keimbahn) in each 
individual through at least a considerable part of its 
life-history, leading up to the formation of basidia, while 
no such cells are found in the Ascomycetes either in 
vegetative or ascogenous hyphae, shows that the two 
groups are widely separated phylogenetically. In the 
face of such differences, resemblances of outer form 
and method of spore-formation between conidiophores 
and basidia must be regarded as superficial and of 
uncertain value, and as wholly inadequate evidence 
for the conclusion Massee wishes to draw/ 
Through lack of appreciation of the value of nuclei 
in indicating affinity or descent no special search was 
made for binucleate cells in the Ascomycetes. Quite 
recently, however, during an investigation of a disease 
of the cultivated mushroom ( Agaricus campestn's) caused 
by Hypomyces perniciosum, a fungus belonging to the 
Ascomycetes, it was observed that the conidial form 
of the Hypomyces known as Mycogone had the cells 
of the hyphae and the conidia constantly binucleate. 
It was also observed that the two nuclei present in the 
conidium fused at an early stage of development, and that on germination the germ- 
tube of the conidium consisted of uninucleate cells. 
• » 
% 
/ 
Fig. 7. Binucleate cells in 
conidial form (Mycogone) of 
Hypomyces perniciosum. 1 . 
Vegetative hypha. 2. Conidio- 
phore with terminal conidium 
containing two nuclei. 3. Con- 
idiophore showing the terminal 
conidium after the fusion of its 
two nuclei. 
The cells of Exoascus deformans , one of the Ascomycetes, are binucleate. 
In Sclerotinia fructigena , also one of the Ascomycetes, the conidial condition 
long known as Monilia fructigena , has both hyphal cells and conidia multinucleate, 
whereas in Sclerotinia aucupariae, an allied species, both hyphal cells and conidia 
of the conidial form are uninucleate. 
1 Journ. Linn. Soc., 34, p. 438 (1900). 
[Annals of Botany, Vol. XIX. No. LXXIV. April, 1905.] 
2 Bot. Gaz., 33, p. 1 (1902). 
