of the Nuclei in Peronospora parasitica . 141 
several. This nucleus passes with the protoplasm into the 
oosphere and coalesces with the nucleus of the ovum. 
He also states that Cystopus appears to agree with the 
above. 
I have examined Cystopus myself, and am inclined to think 
that it agrees more nearly with Peronospora ; on the other 
hand, if Fisch’s observations are correct, it will be seen that 
the process of oosphere-formation in Pythium and Cystopus is, 
extremely unlike that which occurs in Peronospora . 
Chmielewsky’s observations on Cystopus are directly con- 
trary to those of Fisch. He accepts Fisch’s statement for 
Pythium , but says that his observations on Cystopus are 
questionable. He states that the protoplasm of the young 
oogonia has a net-like structure, and the knots of the net, 
which consist of granular plasmatic aggregations, are strongly 
stained, and these are what Fisch must have taken for nuclei. 
He further states that the young oogonium in reality contains 
only one parietal nucleus. This is of considerable size and 
has the form of an ellipse, in one of the foci of which a very 
small nucleolus usually lies. The nucleus is very poor in 
chromatin. 
His observations on the antheridium show that it likewise 
contains only one nucleus in its net-like protoplasm. It has 
equal size and capacity for staining with the nucleus of the 
oosphere. The author calls special attention to this. After 
the passage of the gonoplasm, which takes place through a 
fertilising tube which often penetrates deeply into the oosphere, 
two nuclei were seen which gradually approached nearer to 
each other. The state of fusion was seen. The ripe oospores 
contain always only one nucleus. 
These observations seem to me to be totally different from 
those which I have been able to make upon Cystopus . I quite 
agree with Fisch as to the nuclei present in the oogonium, 
except that I think there are more than he represents. I have 
been able to show that the antheridium contains numerous 
nuclei at a certain stage in its development. The antheridial 
tube, in several cases which I have been able to observe, does 
