760 
Notes. 
process was studied in specimens hardened and stained at different 
stages. In all independent cells, before the protuberances are 
developed, there was found a deeply stained body placed more or 
less in the centre of the cell. This moved to the side of the cell 
to the point where the protuberance was put out, as soon as the 
development of the latter began. It took up a position at the tip 
of this, and remained there during the growth, until contact with the 
corresponding protuberance of the other cell taking part in the con- 
jugation was reached. At the tip of this also a similar deeply stained 
body was situated, and on the fusion of the tips of the protuberances 
the two deeply stained bodies also fused, forming one large body 
filling the greater part of the junction between the two cells. This 
body subsequently divided into two portions, which were withdrawn 
from the neck into the bodies of the cells, and there again they under- 
went, as a rule, another division, each of the bodies so produced 
becoming the basis of a spore. In spite of the controversy as to 
the nature of the Yeast nucleus, there can scarcely be any doubt that 
the deeply stained bodies represent, in part at any rate, the nucleus, 
that consequently a nuclear fusion actually does take place, and that 
the whole process is a kind of isogamous sexual act. 
It was pointed out in the paper that in the case of spore-forma- 
tion in the fission-yeast, Schizosaccharomyces octosporus (Beijerinck), 
a process, somewhat approaching this in nature, was already known 
to occur. Schionning (’95) described the details as follows : — 
Across the middle of a cell a partition- wall was formed : this splits, 
and the two new cells so formed assumed a round shape, remaining 
attached at one point. They then again coalesce, and form an hour- 
glass shaped cell, which increases in size and swells up, until it becomes 
of an oval shape. Spores, usually eight in number, are then formed 
within this. He gave, however, no account of the nuclear behaviour. 
Hoffmeister (’00), in a paper on the nucleus of Yeasts, gave figures 
showing that nuclear fusion took place, when the two cells coalesced, 
before the subsequent divisions of spore-formation occurred. Hence 
this process also must be regarded as a sexual, act. 
Since the publication of the above, Guilliermond has described 
a third case of a sexual act preceding spore-formation among the 
Saccharomycetes. He has not only verified and amplified the results 
of Schionning and Hoffmeister for Schizosaccharomyces octosporus , 
but has also observed a somewhat similar process in Schizosaccharo- 
