56 



by a brusque and instantaneous movement, forming an angle 

 with the anterior part. At the vertex of the angle the body- 

 then ])resents a regular fold, and the animal forms a broken 

 line. Folds can be thus formed in a great number of points, 

 more or less approximated ; and it results from this that the 

 animal can describe a spiral, if all the folds occur on the 

 same side, or twist itself about in various ways. It is probably 

 due to the contractility of the transparent subcuticular layer 

 that the Gregarina has the power of executing these 

 movements. 



3rd. In consequence of the different contractions which 

 are produced, and by the action of which the Gregarina folds 

 itself so as to form broken lines, the granular liquid which 

 occupies the cavity of the cell is seen to move, and the 

 granulations to shift about in the interior of the body of the 

 animal. 



I have found as many as twenty-five Gregarinse in the in- 

 testine of a single Lobster, and at certain times every Lobster 

 presents this parasite. I have observed them in the months 

 of May, of June, and of August, in lobsters coming from the 

 coasts of Norway. It is probable that they will be found 

 equally in those of the coast of Brittanny. I have found no 

 traces of these parasites on Lobsters kept for a long time in 

 captivity in the piscicultural parks at Ostend. Is it the same 

 with the lobster confined in these parks as with the animals 

 of our zoological gardens and the fishes of our aquariums ? 

 May the loss of their parasites be due to their captivity ? 



At the end of the month of last September I examined a 

 great number of lobsters freshly arrived from Norway, with 

 the object of refinding this beautiful Gregarina. Not a single 

 one contained in its intestine the parasite I w^as seeking ; but 

 I perceived that all presented, in the walls of the rectum, 

 little white grains of the size of the head of a small pin. 

 These were the cysts of Gregarinoe, situated beneath the epi- 

 thelium ; and, what is remarkable, the cysts were disposed 

 one by the side of another, forming little rectilinear series of 

 3, 4, 6, and even of 7 cysts. 



13y the beautiful researches of Von Siebold, Henle, Kol- 

 liker, Bruch, Stein, Lieberkuhn, and other eminent natural- 

 ists, the evolution of the Gregarinas has been in great part 

 elucidated. We now know that a single Gregarina may 

 become encysted, and that the frequent fact of the existence 

 of two granular masses in the same cyst is explained by the 

 division of the contents of the encysted Gregarina, and not 

 by the conjunction of two Gregarinse in one and the same 

 cyst, as Stein and other naturalists had supj^osed. It is 



