MEMOIRS. 



Remarks on the Structure of the Gregarin.^. By Pro- 

 fessor Edward van Beneden. (With Plate XL) 



In a work published in the ' Bulletins of the Royal Aca- 

 demy of Belgium' (vol. xxxi, No. 5, 1871)^ and ' Quart. 

 Journ. Micro. Science ' (vol, xi, new ser.), 1 have made 

 known the successive conditions of the evolution of a new 

 Gregarin found in the intestines of the lobster, and de- 

 scribed on a former occasion under the name of Gregariria 

 gigantea (' Report of the Royal Academy of Belgium/ vol. 

 xxix, No. 11, 1869, and ' Quar. Journ. Micro. Science,' 

 vol. ix, new ser.). I have established through my inves- 

 tigations that the psorosperms give birth to small proto- 

 plasmic globes, which differ from Amoebse in that they are 

 devoid of all cell-nucleus, and in that they never show 

 any trace of vacuole. They represent, from a morphologic 

 point of view, the Monera of Haeckel, and the Gregarinae 

 pass, during the course of their autogenic evolution, through 

 the Monerian condition. At that time they are simple gym- 

 nocytods, and only become cells when a nucleus deve- 

 lops itself in their interior. On the surface of each cytod 

 grow two protoplasmic prolongations. Simple buds in their 

 beginning, these prolongations stretch out, absorbing at the 

 same time the body of the cytod, and when they become 

 free they move in the intestines of the lobster, like little 

 nematod worms. From thence the name of Pseudofilaria, 

 which I have given them. Not long after, they become 

 shorter, and at the same time their movements become 

 less active ; they soon cease altogether ; a voluminous 

 nucleolus then appears inside the body, this at once be- 

 coming surrounded by a nuclear coating. From this time 

 the cytod has become a cell ; the separation of the chemical 

 elements of the nucleolus and of the nucleus from the 

 essential elements of the body of the cell has led to the 

 differentiation of the original matter, which I have called" plas- 

 son," into three distinct layers — the nucleolus, the nucleus, 

 and the protoplasma.^ 



' The beautiful observations that, Elmer has recently published on the 

 VOL. XII. NEW SER. Q 



