Dale . — Observations on Gymnoascaceae . 579 
cells are of approximately the same size and shape, so that 
the apex of the ascogone and of the sterile cell are at the same 
level, the prolongation winds loosely and irregularly round 
the two cells (Fig. 1 5) ; but if the sterile cell is larger, so 
that the point of fusion lies some distance from its apex, 
the prolongation of the carpogone, at least at first, winds 
closely round the sterile cell (Fig. 14). 
After forming a considerable coil round the original con- 
jugating cells the prolongation of the ascogone becomes 
segmented, as may be seen in solid preparations (Figs. 17 
and 19) and also in longitudinal and transverse sections 
(Figs. 18, 29 c). From most of these segments, not merely 
from one or two, short thick branches grow out, and soon 
themselves branch (Fig. 18) and form a dense mass of hyphae 
(Figs. 19 and 20). These are the ascogenous hyphae, and 
their ends swell up into the rounded asci. 
From below the sterile cell, and possibly from below the 
ascogone also, there eventually grow out a few vegetative 
hyphae which are longer, thinner, and straighter than the 
ascogenous hyphae (Fig. 21), but they do not arise till 
a considerably later stage in the development is reached. 
With regard to the behaviour of the nuclei the following 
facts have been observed. When the two hyphae forming 
the coil are still quite small each contains a single nucleus 
of considerable size, in which may usually be seen a nucleolus 
surrounded by a nuclear zone (Figs. 22 and 23). 
At the time of conjugation, however, both cells contain large 
members of nuclei , which, at least in certain stages, have each 
a distinct nucleolus and nuclear zone (Figs. 27 and 28). These 
nuclei must apparently have arisen by division from the 
original single nucleus, and .cases were noticed, which seem 
to be intermediate stages, in which there were several, but 
far fewer, nuclei (Figs. 24, 25, and 26). As the nuclei divide 
they become smaller in size, because the growth of the 
divided nuclei does not keep pace with division. When 
division is completed the nuclei grow until they attain their 
permanent size. The cells themselves are usually completely 
