Miscellaneous. 63 



the optic nerve. Among the large cells small ones are observed. 

 As M. AVeissmann has shown, each of the large cells will become 

 one of the simple eyes, the totality of which constitutes the retina. 

 The small cells become the choroid cells. 



My predecessors, who had not observed the destruction of the 

 integuments of the later segments of the larva, thought that the 

 integuments of the abdomen of the adult were formed by a simple 

 transformation of the hypodermic cells of the latter. Having already 

 shown that the whole of the skin of the larva disappears, I had to 

 ascertain how the integuments of the abdomen of the adult are de- 

 veloped. I have ascertained that they are formed at the expense of 

 the embryonic cells which fill the body of the pupa, and the origin 

 of which has been indicated above. These embryonic cells become 

 converted into hypodermic cells. This change does not take place 

 at all points of the abdomen at the same time ; but, in each seg- 

 ment, the hypodermis of the ^dult appears at first at four points, 

 two below and two above. 



As the organs of the larva disappear, and the organs of the adult 

 are formed, the nervous centres undergo very important internal 

 modifications. Their investigation, which has not even been touched 

 upon, is environed with technical difficulties. I have succeeded in 

 overcoming nearly all of these. I have traced step by step the inter- 

 nal modifications that the nervous centres undergo during pupal 

 life ; and I shall shortly have the honour to make known to the 

 Academy the principal results of my researches upon this subject. — 

 Comptes Bendiis, Nov. 14, 1881, p. 800. 



Development of the Ovum of Melicerta. By M. L. Joliet. 



The development of the embryo of the Eotatoria has hitherto 

 been studied only in two genera, namely in Brachionus by 8alensky, 

 and in Pedalion by Barrois. The mode of segmentation is still 

 unknown. 



Although we have ascertained that the development of the winter 

 egg and of the male e^^ agrees generally with that of the female 

 summer egg, it is more particularly upon this last that our investi- 

 gations have been made. 



Within the sac of maturation it presents, in the midst of the 

 germinal vesicle, a small but very distinct germinal spot. After 

 deposition this spot soon disappears. It did not apjjcar to me that 

 there was any emission of a polar globule. The first segmentation- 

 plane, perpendicular to the larger axis of the eg^, which is an irre- 

 gular ovoid, divides it into two very unequal segments. Afterwards 

 these two segments divide symmetrically, and so that each of them 

 furnishes eight of the spheres which constitute the egg in the stage 

 XVI. We observe only that the spheres derived from the larger 

 primary segment are larger than the others, and larger in propor- 

 tion to their distance from the animal pole. It seems as if each 

 of them had a certain degree of animality. During the whole 



