1905] BRIEFER ARTICLES 63 
surviving asters with their accompanying nuclei become the centers around 
which the cleavage of the protoplasm proceeds to form the eggs. TROW 
calls the egg-asters ‘‘ovicentra.”” He believes that the number of chromo- 
somes shown in the first mitosis is reduced by half to form four in the 
second, so that the latter is a reduction division in oogenesis. 
TRow’s account of the development of his ovicentra is fundamentally 
different from mine. I regarded them as simply representing dynamic 
centers of the protoplasm without any relation to mitotic phenomena, 
centrosomes, or asters, and as strictly comparable to the coenocentra of 
the Peronosporales. ‘Trow considers them centrosomes in an aster (astro- 
spheres) appearing at a final reduction division (second mitosis) in the 
- oogonium. The situation has become very much complicated. If ovi- 
a { centra are the same as coenocentra, why have not the latter been found 
. associated with mitotic figures in the Peronosporales, where the structures 
-) are large and have been much studied? Is it possible that we have a new 
q *\ structure in the Saprolegniales? Tam not willing to give up my view of 
oogenesis, although I can at once see the necessity of further investigation 
in both the Saprolegniales and Peronosporales. I do not think that 
Trow has presented enough evidence or treated the subject sufficiently 
with reference to the Peronosporales to be convincing. His theory is 
based, so I understand, chiefly upon the sections from one oogonium. 
. There are some interesting questions suggested by the group of figures 
, numbered 18, which one hesitates to ask without seeing TRow’s prepara- i 
i; tions. But why are not the asters present at metaphase, the time when 
4. such structures are generally most conspicuous? And again, why are the 
asters sometimes so far away from the poles at anaphase (jig. 188)? Is it 
_ possible that the ‘‘anaphase” is simply a resting nucleus drawn out towards 
a coenocentrum and attracted by it, as is the habit in the Peronosporales ? 
These questions are not put in a captious spirit, but by one who is deeply 
interested in the problem and knows the difficulty of the investigations. 
i! Trow has advanced a most interesting hypothesis, which he must expect 
| to be keenly scrutinized. 
‘“The sperm nucleus soon after its entry into the oosphere acquires a 
distinct centrosome and astrosphere.” This seems to the writer the most 
remarkable announcement in TRow’s paper. Neither the origin nor the 
fate of this structure was followed. It looks exactly like an ovicentrum. 
The male and female nuclei and their accompanying astrospheres remain 
quite apart in the egg until the astrospheres disappear. In the meantime 
the oospore gradually fills with reserve material and the wall thickens. 
While these processes are under way the gamete nuclei fuse. The structure 
