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
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