36 Fraser . — Contributions to the Cytology of 
tinguished, under a lens, from the white or yellow sand grains among which 
they grow, and the youngest stages were only secured when they remained 
attached to an older ascocarp after the sand had been cleaned away. 
The hypothecium is formed as a loose tangle of septate hyphae, which 
show somewhat scanty cytoplasm and a few granules. Each cell contains 
one or a few nuclei. These show a reticulum with conspicuous net-knots ; 
a nucleolus may or may not be present ; evidence of the occurrence of 
a central-body, as described by Harper ( 31 ) for Phyllactinia , or of the attach- 
ment of the chromatin filaments at a particular point, was not obtained. 
Nuclear divisions in the hypothecium are karyokinetic (Fig. 3); the 
chromosomes are densely massed on the spindle and could not be counted ; 
early prophases were not identified with certainty. 
The nuclei at this time are of two sizes, and the smaller nuclei are 
seen to fuse in pairs , thus giving rise to the larger. Such fusions are very 
readily observed in all but the youngest ascocarps, and show the usual 
series of dumb-bell shaped figures (Figs. 4,5). Migration of a nucleus from 
one cell to another occasionally takes place (Fig. 6), no doubt in connexion 
with these fusions ; but, whereas more than twenty fusions were counted, 
migration was only twice observed. It seems likely, therefore, that it is 
not of general occurrence, and that the two nuclei which fuse have often 
been present in the same cell since their formation. 
Ascus Formation. 
The paraphyses are now differentiated, and, soon after, the first asci 
appear. In the subhymenial layer nuclei of two sizes are. present, the 
larger being in the ascogenous hyphae, the smaller in the paraphyses and 
the cells from which they arise. The nuclei of the ascogenous hyphae 
at first resemble the fusion nuclei of the hypothecium in size and general 
structure (Fig. 7 a), and there seems no reason to doubt that they correspond 
to them, and that the nuclei in the paraphyses are to be related to the nuclei 
which have not undergone fusion. 
As the ascogenous hyphae develop, their nuclei increase in size, and 
become vacuolate in structure (Fig. 7 b). Eventually the two terminal 
nuclei of the hyphae undergo simultaneous karyokinetic division. This 
may take place, either before (Fig. 10), or after (Figs. 8, 11), the hypha 
bends over to form the crozier first described by Dangeard ( 11 ) in 1894. 
In the early prophases of this division the nucleus shows a definite spireme, 
and large, centrosome-like bodies are present (Fig. 8). The spireme breaks 
up into about sixteen curved chromosomes (Fig. 9). These become densely 
massed on the spindle (Fig. 10), and eventually pass to the poles (Fig. 11). 
A terminal, uninucleate and a penultimate, binucleate, cell are formed, the 
two nuclei in the latter being sisters respectively of those in the terminal 
cell and the stalk-cell. 
