66o Miyake.— The Fertilization of 
Wager (’96) and Davis (’00) in one essential point. Stevens 
(’01) found that in Cystopus candidus the nucleus of the 
oosphere was derived from one of the nuclei which remained 
in the ooplasm from the time of its differentiation, instead of 
coming to the non-nucleated centre of the ooplasm from the 
periphery. Thus he states that at no time of its development 
is the central region of the oosphere entirely free from a nucleus, 
and in this respect Cystopus candidus differs from the other 
species of the genus. 
In the antheridium, after division, all the nuclei degenerate 
except one which becomes enlarged (Fig. 18). While the 
oosphere is differentiating, the antheridium puts out a fertiliza- 
tion-tube from the point of attachment into the oogonium, 
piercing through the wall of the latter and pushing its way 
through the periplasm into the ooplasm (Figs. 19-22). The 
fertilization-tube is a thin-walled cylindrical tube, often some- 
what narrowed at the end, instead of being enlarged as in 
Peronospora and Cystopus. The tube does not seem to reach 
deep into the centre of the oosphere, as in many species of 
Peronosporeae, but it appears to open near the periphery 
of the oosphere. I am not, however, very certain on this 
point, as in a few preparations something like the fertilization- 
tube was seen to reach the centre of the oosphere from the 
periplasm. 
The greater part of the antheridial contents with the male 
nucleus passes gradually into the oosphere through the 
fertilization-tube (Fig. 19). The nucleus of the antheridium, 
after entering the oosphere, comes in contact with the female 
nucleus in the centre, and then they fuse together to form the 
nucleus of the oospore (Figs. 20-22). 
It would be interesting to study the behaviour of the nuclei 
during fertilization in the oogonium with more than one 
antheridium. De Bary (’84) mentions that, if there is more 
than one antheridium, they all usually, but not always, empty 
their gonoplasm one after another into the oosphere. My 
present investigation has so far failed to make this point 
clear. 
