BERTEAMIA KIEKMANI. 13 



On July 8th the average size of the four largest bodies was 

 96 ju in length and 24 /x in breadth. The specimen was now 

 unobserved until July 14th, when all the bodies except one 

 had become divided up into a mass of spores without encyst- 

 ing. One specimen had become encysted; it was rounded in 

 shape, and about 39 /x in diameter. The thickness of the 

 cyst was about 5'5 ju. The protoplasm had not become divided 

 up into spores. 



On July 24th the encysted specimen burst, and the spores 

 were liberated. The non-encysted individuals had broken 

 up into loose spores several days previously. The rotifer had 

 died on the 20th of the month. The cyst-wall is highly 

 elastic, for on the liberation of the spores the empty cyst 

 contracted to half of its previous size. This elasticity of the 

 cyst- wall must act very effectively in forcing out the contained 

 spores. From this account we can see that the rotifer must 

 have lived for more than three weeks in a parasitised con- 

 dition. 



In a few days the body of the rotifer disintegrated, and 

 the spores were scattered through the water. Into the water 

 a non-parasitised specimen was introduced ; but the animal 

 died in about a fortnight and did not become infected. 



Another specimen containing trophozoites was observed on 

 June 21st. The host was dead on the 2ord, and the parasites 

 had completely broken n}) into loose spores on the 27th. 



In the material at my disposal I have been nnable to trace 

 the path of the sjiorozoite into the body-cavity of the host. 

 It is, of course, probable that the spores are swallowed, and 

 that the sporozoites escape through the operculum of the 

 spore-membrane and penetrate some part of the alimentary 

 canal ; but in all my sections no trace of sporozoites in the 

 wall of the alimentary canal could be detected. 



The youngest trophozoite found contained, as already 

 stated, two nuclei ; while the number of nuclei in the sporo 

 plasm amounts to six to ten, on the supposition that the 

 isolated masses of chromatin above described are to be 

 regarded as nuclei. It would consequently follow that the 



