412 
HARRY M. FITZPATRICK 
Maire (36), having re-examined the species (Auricularia mesen- 
terica) studied by Juel, states the chromosome number to be two. He 
terms the bodies figured by Juel protochromosomes, and maintains 
that two is the constant haploid chromosome number in all the Basid- 
iomycetes (Ishikawa, 23; Tischler, 50). His figures show that after 
the division of the fusion nucleus in this species no septum is laid 
down until the spindles of the second division are already formed. 
A two-celled basidium exists for a very brief period. Since the 
daughter nuclei of the fusion nucleus do not always divide simul- 
taneously, the two septa last formed are occasionally laid down in- 
dependently. A case of this kind, in which the basidium contains 
only two of its three septa, is figured. 
None of these investigators describe conjugate divisions in the 
hyphae. They do not even show that a binucleate condition is a 
constant characteristic of any definite portion of the life cycle. Their 
accounts of the nuclear divisions in the basidium are contradictory, 
and nuclear phenomena following spore germination are not described. 
Our knowledge of the nuclear history and general cytology of the 
higher Hymenomycetes and Gastromycetes is also still far from satis- 
factory. The basidia in practically all described cases are binucleate 
in the young condition, and arise from binucleate cells in the subhy- 
menium. Other cells in the hyphae of the sporophore or in the nutri- 
tive mycelium may be uninucleate or multinucleate. The accounts 
of different investigators differ greatly with respect to the point of 
origin of the binucleate condition in different species. The bulk of 
the evidence seems to show that the nuclear pairs do not arise at any 
given point or in any specialized manner. Recently Kniep (28), 
working with Corticium varians Kniep and C. serum Pers., has reached 
the conclusion that the binucleate condition is initiated and main- 
tained by means of clamp connections. He points out also that the 
basidium is frequently connected by a clamp connection with the cell 
below, and he presents an interesting argument to show that the 
basidium is homologous with the ascus. He likens the formation of 
the clamp connection on the basidium to crozier formation on the 
ascogenous hypha, and homologizes the terminal cell of the clamp 
with that of the ascus hook. His work is extremely interesting since 
it furnishes the most plausible explanation yet advanced of the 
function of the clamp connections in the Basidiomycetes. His 
theory fails, however, to explain the large number of described cases 
