168 SUMMARY OF CURRENT RESEARCHES RELATING TO 



his account of them differs in some noteworthy respects from that given 

 by previous investigators. He has traced their development from a cell 

 with a single nucleus, through stages with two, four, eight, sixteen, and 

 thirty-two nuclei. The chromatophore is not formed by a secondary 

 combination of originally separate elements, it is a single, complex, 

 multinucleate cell. One large and peculiar nucleus remains in the 

 centre ; the others are disposed peripherally at the bases of the radiating 

 contractile processes. The resemblance to a multinucleate Protozoon is 

 striking. 



The radiating contractile fibres are not secondarily connected with 

 the central pigmented portion, but arise from it primarily, just like 

 pseudopodia. Kolliker's old conclusion that the radial fibres are con- 

 tractile and act in the expansion of the chromatophore is quite correct, 

 but the fibres are parts of the chromatophore. The contraction of the 

 chromatophore is due to contractile arcs at the margin of the cell, 

 stretching like bows between the basal portions of adjacent radial fibres. 

 Some of Chun's figures are very striking. 



New Cuttle-fishes.* — L. Jourdain makes a brief communication in 

 regard to the Cephalopods collected in 1901-2 by the Prince of Monaco, 

 chiefly in the vicinity of the Azores. There is a large species of Cirro- 

 teuthis (C. grimaldii sp. n.), notable for its massive ovoid form and 

 gelatinous consistence. The arms are enveloped in a thick membrane 

 which almost masks them, only the tips being free ; there is no separa- 

 tion between arms and head, or between head and body, the whole being 

 enclosed in a cutaneous envelope. Very different is the small C.richardi 

 sp. n. The author makes short notes on EledoneUa diapliana Hoyle, 

 the third specimen known, remarkable for its soft and transparent 

 tissues ; on Leachia cyclura Lesueur which has luminous organs ; and 

 on a new species of Rossia (R. caroli) with enormous eyes which make 

 the head bigger than the rest of the body. 



Chorion and Micropyle in Cephalopods.f — A. Schweikart has fol- 

 lowed up Bergmann's research on oogenesis in Cephalopods, and has 

 utilised some of his slides. The chorion begins to be formed by the 

 separation of drops or granules from the follicular epithelium ; these 

 coalesce into a continuous homogeneous membrane. The stages in the 

 formation are described with particular reference to Sepiola, where the 

 truly chorionic nature of the envelope is very clear. The formation of 

 the micropyle as a canal traversing the chorion at its thin region over 

 the animal pole is described with special reference to Rossia macrosoma. 



y. Gastropoda. 



Retina of Gastropod Eye.J — Pt. Hesse notes that previous investi- 

 gators are at one in describing two kinds of cells in the retina of the 

 Gastropod eye — pigmented and unpigmented — but that there is no 

 unanimity as to which kind of cell is sensory. Some say the pigmented 

 cells are optic, others say the unpigmented, others say both. The 



* Com]tes Rcndus, oxxxvi. (1903) pp. 100-2. 



t Zool. Anzeig., xxvi. (1903) pp. 214-21 (2 tigs.). 



\ Ve:h. Doutsch. Zool. Ges., xii. Vers. (1902) pp. 121-5 (2 figs.). 



