142 Wager. — Observations on the Structure 
not penetrate deeply into the oosphere, although it appears to 
do so, but takes an oblique course to one side, as is the case 
in Peronospora. Lastly, I have noticed that the ripe oospore 
contains numerous nuclei, and this appears to agree with 
Zalewski’s 1 observations. I propose to thoroughly investigate 
this question as to the formation of the oospore, fertilisation, 
and structure of the nucleus in Cystopus during the coming 
winter. 
The Nuclei of the Gonidia. 
The gonidia or zoosporangia, as before mentioned, are borne 
at the tips of branches of much-branched gonidiophores. They 
contain a very dense protoplasm, and numerous nuclei (Fig. 19 ). 
The nuclei are slightly larger than those which occur in the 
mycelium, and have a different structure. They are spherical 
or slightly oval bodies, with a very distinct outline. Each 
nucleus contains a small central mass of chromatin, surrounded 
by a less deeply staining nucleoplasm. I have not been able 
to observe any division in these nuclei, and I have not been 
able to determine whence they are derived, whether from the 
mycelium or from the division of a single original nucleus or 
nuclei in the sporangium. 
In conclusion, I have to thank Dr. D. H. Scott for suggesting 
the work which led to this investigation ; and I wish here also 
to thank him very heartily for his great kindness while the 
work was in progress. A part of it was done in Dr. Scott’s 
laboratory at the Royal School of Mines, and a considerable 
portion was done in the biological laboratory at the York- 
shire College, but it was chiefly owing to the facilities afforded 
me in July of 1889 by Dr. Scott, at South Kensington, where 
he placed a set of apochromatic lenses at my disposal, that 
I was enabled to complete the work satisfactorily. 
Summary. 
The various organs of Peronospora parasitica , the mycelium, 
antheridia, oogonia, and gonidia, contain numerous deeply- 
1 Loc. cit. 
