FIG. 25. Different stages in the fertilisation of Pero nospora parasitica. 

 i, young oogonium with antheridium and receptive papilla, where the 

 antheridium is in contact with the oogonium ; numerous nuclei are 

 present in each organ. 2, the central body (coenocentrum) is very distinct, 

 and a single nucleus from the periplasm is in contact with it. A nucleus 

 is just about to pass from the antheridium into the fertilising tube. 3, 

 showing the sexual nuclei in contact and just beginning to fuse. The 

 wall of the oospore is now formed separating the ooplasm from the peri- 

 plasm. All the nuclei originally in the oospore, with the exception of the 

 one female nucleus that is fusing with the male nucleus, now lie in the 

 periplasm. 4, the fusion nucleus, resulting from the fusion of the male 

 and female nuclei, shows a distinct network and a single nucleolus. 

 (After Wager. ) All highly mag. 



