PLATE 63 



Rhizidiomyces apophysatus 

 on 



ACHLYA CONSPICUA 



Figs. 1-5. Oogonia infected with the parasite to a greater or less extent. In Fig. i the form- 

 ation of eggs has been prevented by an early attack. The parasite shows the 

 rhizoidial rootlets entering the protoplasm of the host, the stalk passing to 

 the exterior which is often swollen to form an apophysis (a), and the exterior 

 swelling which becomes the sporangium (b). All X 503. 



Fig. 6. The same oogonium shown in Fig. 5 drawn 16 hours later, the sporangium (b) now 

 full size and showing the spore initials. X 503. 



Figs. 7-13. The same sporangium (b) shown in Fig. 6, with the resulting spores, the figures 

 drawn at intervals of about 10 minutes. The sac (c), in which the spores are 

 emptied, is shown free in Fig. 12, and fully developed spores in Fig. 13, just 

 after the disappearance of the sac membrane. All X 503. 



Fig. 14. Two active spores with a single cilium each. X 1028. 



