Miscellaneous. 99 



the influence of excitations coming through the eye of the opposite 

 side. 



/. The luminous rays belonging to the blue-violet region of the 

 spectrum act directly upon the contractile matter of the corpuscles, 

 causing them to move and to approach the surface of the skin. 



I think I am justified in expressing the hope that these investiga- 

 tions veil! at last throw some light upon the history of the vaso- 

 dilatator nerves, of which so little is known ; they will also serve 

 me as a starting point for studying the action that light must exercise 

 upon the contractile substance under other circumstances, and parti- 

 cularly upon the sanguiferous capillaries of the human skin. — 

 Comptes Rendus, November 22, 1875, p. 938. 



Oh the Anatomif and Histology of Lucernaria. 



By M. A. DE KOROTTNEFF. 



During the summer of the present year I occupied myself with the 

 anatomical and histological investigation oi Lucernaria octoradiata 

 in the laboratory of M. de Lacaze-Duthiers at Roscoff. The abun- 

 dance of the animal and the perfect arrangement of the laboratory 

 enabled me quickly to arrive at the results which I now communi- 

 cate to the Academy. 



The walls of the body consist of four layers: — 1, the ectoderm, 

 covered by a cuticle ; 2, the gelatinous layer ; 3, the elastic mem- 

 brane ; 4, the entoderm. At the bottom of the ectoderm, as well 

 as in the entoderm, there are cells which become transformed into 

 nematocysts or into glandular cells. The gelatinous layer and the 

 membrana propria are traversed by elastic fibrils, which are pro- 

 longations of the entodermic cells. Two kinds of muscles occur in 

 th.e Lucernaria, longitudinal and circular; the latter always form an 

 exterior layer. The longitudinal muscles are represented by four 

 trunks, which commence at the bottom of the foot. Halfway up 

 the body of the animal each trunk divides into two rods ; and each 

 rod enters into a bundle of tentacles. A layer of longitudinal mus- 

 cular fibres occurs in the walls of the peristome and of the buccal 

 tube. The circular muscles exist (1) round the mouth, (2) along 

 the margins of the body, and (3) in the tentacles. Each fibre is a 

 simple cell, containing a very refractive fibril. The cells may 

 unite by prolongations and develop a single fibril, which traverses 

 a whole scries of cells. The fibril grows at the expense of the 

 cell itself ; the protoplasm of the latter disappears almost entirely, 

 and the nucleus is enclosed in the fibrous mass. The peristome on 

 its outer surface is clothed with well-developed muscular cells ; 

 these cells at the same time separate a perforated cuticle ; the 

 presence of the latter proves that it is a layer of a muscular epi- 

 thelium. 



With regard to the nervous system of the Hydraria there are 

 many suppositions, but nothing is positively known. Kleinenberg, 

 without much reason, attributes a nervous character to the cells of 



