Reproduction of Cystopus Candidus , Ldv. 333 
that the amount of protoplasm which passes over is very 
small ; but do not agree with the observations made on 
Pythimn , that nearly the whole of the protoplasm passes 
over. If it be found that the antheridium of Pythium 
contains numerous nuclei, and that these all pass over into 
the oosphere, as would appear to be clearly indicated by 
Marshall Ward and De Bary, and perhaps Fisch, it will 
afford an interesting comparison with Cystopus , and will 
probably lead to interesting results. 
That fertilization takes place in the Saprolegniae as 
described by Trow, or as indicated by me for Peronospora , 
without the penetration of a fertilizing tube into the oosphere, 
would appear to be extremely doubtful in the light of these 
observations on Cystopus. If fertilization does take place in 
the manner described, then we have simply the passage of 
a male nucleus from the fertilizing tube through the proto- 
plasm of the oosphere to the female nucleus without the 
intervention of a fertilizing tube, a state of affairs which 
is now known to take place, with the exception of a few 
little-investigated cases, only when antherozoids are formed. 
In all other cases, where the conditions under which the 
plant is grown do not allow the formation of antherozoids 
or motile spermatia, the male nucleus is carried right into 
the oosphere by a fertilizing tube : whilst in the archegoniate 
plants and in Vaucheria , a substance is excreted or formed 
which conducts the antherozoid down to the oosphere. Such 
evidence as this tends to show therefore that fertilization as 
is described in Saprolegnia by mere contact of a fertilizing 
tube with the oosphere, and subsequent passage of the male 
nucleus through it into the oosphere, does not take place as 
a rule. 
Another interesting point to which it may be well to call 
attention is that the process of fertilization as here described 
does not differ in any essential particular from the process as 
it takes place in the Angiosperms, if we except the part 
played by the centrospheres, which I was not able to observe 
in Cystopus. In the Angiosperms, for example, according to 
