66 



PROTESTS AND DISEASE 



seen in Saprolegnia. The point of attachment of the flagellum 

 is hard to see. 



Only a small percentage of zoospores effect an entry 



Hi\ 



FIG. 16. NUCLEAR PROCESSES IN OLPIDIOPSIS. a, zoospores of 0. Sapro- 

 legniae ; b, the same of O. vexans, the lower one stained ; c, early 

 stage, non-sexual ; d, nuclear division ; e, early sporangium, resting 

 nuclei and internal vacuole ; /, sporangium, separate zoospores 

 formed ; g, zygospore, contents of antheridium passing into oogonium ; 

 h, the same stained ; i, ripe oospore. After J. T. Barrett. 



into a host. Entry is as shown in Fig. 15, G to /. The 

 parasite at first contains but few granules, these grow and 

 coalesce into oil-like drops, which are replaced by vacuoles 

 at maturity when exit tubes are formed. 



