xLvi NOTES ET REVUE 



nuclear membrane and the plasmosomes. The chromatin of tlie 

 nucleus fragments into 8 to 18 portions, distributed fairly evenly 

 through the protoplasm. The protoplasm segregates round thèse 

 nuclear masses, and a small, indeOnite number of merozoites, each 

 abolit o tj. to 6 [x long and 1 a broad are prodiiced. Thèse break 

 through into the gut singly, not simultaneously as is the case with 

 many Schizogregarines, sometimes using thechannelby which the 

 parent organisai entered, sometimes forming a new one by bursting 

 through the tenuous film of protoplasm which represents the 

 original epithelial cells of the gut. 



The number of schizonts is very great, and consequently the 

 number of merozoites is still greater, and as thèse merozoites 

 (schizozoites of Léger [5]) serve for auto-infection, Ihe crowd of 

 trophozoites of the second génération, observable in certain of the 

 Ascidian guis, is easily understood. 



Sporogony occurs in the lumen of the gut. Two trophozoites, often 

 lying near the gut wall, come in contact and associate. The proto- 

 plasm of thèse gamètes is less granular and the nucleus more 

 concentrated than in the free forms. As a resuit of this association, 

 a sporocyst about 14 ;j. long and 11 [x broad is produced. The sporo- 

 cysts are very refrac tile and hâve a défini te, oval cou tour. Withinthem, 

 eight small, falciform, uninucleate sporozoites are formed. Thèse are 

 arranged " en barillet ". The sporozoites serve for cross-infection. 



Merogregarina bas a distinct efTect on the animal harbouring it. 

 The free trophozoite withdraws nutriment by means of ils epime- 

 rite from the gut cells of the host. The cell pierced by the epimerite 

 is itself deprived of its nutriment and the growth ceases. 

 INeighbouring cells become alTecled though to a less extent and the 

 resuit is that the parasite comes to lie in a bay or dépression in the 

 epithelium of the gut, the bay being produced by the progressive 

 atrophy of the cells. 



In the case of the young schizont, the opposite efTect is seen, for 

 the cells in the neighbourhood of the invading parasite are stimu- 

 lated by it in such a way that they hypertrophy, and on the issue of 

 the merozoites the cells inay remain ruptured, wlien the effect of 

 the parasite is évident; but, as a rule, the channel formed closes 

 up as soon as the parasites bave emerged into the lumen of the gut. 



The life history may be brietly suinmarised as follows : — A 

 merozoite or sporozoite pénétrâtes the epithelium of the gut of the 



