Nichols—Binucleated Cells in Some Basidiomyceles. 59 
found evidence of conjugate division in tlie hyphae but it seems 
possible that it exists and that the two nuclei of the young 
basidia have remained distinct throughout the series of binu¬ 
cleated cells. 
The evidence seems satisfactory that in the rusts the series of 
nuclei in the binucleated cells are formed by the association of 
two nuclei in so called conjugate division. A wall is formed be¬ 
tween the two pairs of daughter nuclei. Thus the two nuclei in 
a cell are not sister nuclei. The nuclei which fuse in the teleuto- 
spore have thus remained distinct through generations of binu¬ 
cleated cells. The wide occurrence of a series of binucleated 
cells in the young carpophore suggests a method of division sim¬ 
ilar to that in the rusts. Maire believes that the series of nuclei 
in the binucleated cells of the forms studied by him are formed 
by conjugate division but his figures do not seem conclusive. In 
Hypholoma and Coprmus each of the four spores borne on the 
basidium receives a single nucleus which immediately divides 
forming a binucleated spore. Maire states that a similar process 
occurs in Clavaria vermicularis, Clitocyhe aurantium, Mycena 
galericulata, and Amanita pantherina. This resemblance be¬ 
tween the nuclear history of the Uredineae and of the Basidiomy - 
cetes has been discussed fully by Maire, Harper and others. 
In view of the fact that the hyphae with binucleated cells are 
found originating from uninueleated cells in Coprinus, it is very 
possible that further study may reveal some forms in which the 
mycelium will show regularly uninueleated cells and that this 
uninueleated series will extend to the first formation of a carpo¬ 
phore. 
At present there is no evidence that the binucleated cells of 
the Basidiomyceles ever originate by a fusion of two adjacent 
cells such as Blackman (2) finds at the base of the aecidium in 
Phragmidium violaceum and Gymnosporangium clavariaeforme. 
The occurrence of regular binucleated cells through a large 
part of the life history of the Basidiomyceles leading to the 
formation of basidia while binucleated cells are unknown in the 
life history of the Ascomycetes makes it difficult to consider the 
two groups as phylogenetieally related. Maire (16) states that 
binucleated cells occur in the ascogenous hyphae in Pustularm 
