964 AQUA TIC PH YCOMYCETES 



IMPERFECTLY KNOWN GENUS OF THE OLPIDIOPSIDACEAE 



? BLASTULIDIOPSIS Sigot 

 C. R. Soc. Biol. (Strasbourg), 108: 34, 3 figs. 1931 



? BLASTULIDIOPSIS CHATTONI SigOt 



Loc. cit. 



Zoospore upon coming to rest on the host cell losing its flagella and 

 producing a tube that penetrates the host wall and forms within the 

 host a short filament, which enlarges, expands, and branches, the branch- 

 es forming broad lobes of varying size, the whole thallus transformed 

 at maturity into a single sporangium; zoospores 6-8 [L (long?) with two 

 laterally attached opposed flagella, 15-20 [i in length, and an anterior 

 globule, formed within the sporangium, where individual movement is 

 initiated, and escaping through a pore at the tip of a short discharge 

 tube; resting spore not observed. 



Parasitic in eggs of Cyclops (fresh-water crustacean), France. 



The thallus is said to be plasmodial and unwalled until just before 

 formation of the zoospores. In the course of development several large 

 vacuoles appear in the cytoplasm, which fuse to form a single large one. 

 The nuclei at maturity are distributed regularly in the cytoplasm sur- 

 rounding the central vacuole; the spores are cleaved out simultaneously 

 around each of the nuclei. 



In the method of formation of the zoospores, their activity within the 

 sporangium, their manner of discharge, and their structure Blastulid- 

 iopsis resembles Olpidiopsis. Its zoospores are, however, much larger. 

 The lobed nature of the sporangium constitutes a strong resemblance 



to Petersen ia. 



The method whereby the zoospore reaches the eggs of the host, 

 which are still within the egg sac of the animal, is not given by Sigot. He 

 noted that the period of time necessary from infection to sporulation 

 of the parasite was about equal to the time between fertilization and the 

 occurrence of the Nauplius stage of the crustacean. The disease appeared 

 in late February or early March and disappeared during May. 



The form is difficult to typify because the observations have in the 

 main been derived from sectioned and stained material. Further work 



