26 Mr. H. J. Carter on the ^perinatology of a new species o/Nais. 



of a cell-wall, vesicles, nucleus and albuminous centre, like the 

 floating-cells, but with the following exceptions, viz. — that some 

 of the "vesicles," though retaining their original shape, have 

 acquired a yellowish tinge ; others have become of an amber- 

 colour, and have flowed together to form bile-globules ; while a 

 third set have apparently shrunk into abortive, brownish, or 

 colourless granules; many also of the hepatic cells have lost 

 their cell- wall, thus leaving nothing but the parts just men- 

 tioned adhering to the surface of the albuminous sphere (fig. 8 a). 

 The hepatic cells are so loosely attached to the intestine, that, 

 under the slightest pressure, many of them separate from it, and 

 may be observed free among the floating-cells of the peritoneal 

 cavity, when the only difference that can be observed between 

 those which are spherical and the floating-cells, is the yellow 

 tinge of the vesicles : neither is there any earlier stage of deve- 

 lopment of these cells than this in the hepatic layer ; hence it 

 becomes a question, from whence are the hepatic cells originally 

 derived ? 



To me, the hepatic cells appear to be merely the final stages 

 of development of the floating-cells, for the following reasons : 

 First, from there being no cells earlier in development in the 

 hepatic layer than those of a spherical form, in which the vesi- 

 cles are already tinged yellow, and in which state, but for the 

 presence of this colour, they would be undistinguishable from 

 the floating-cells. Secondly, from the hepatic cells being en- 

 closed by no general membrane, but attached loosely to the 

 surface of the intestine. Thirdly, from the plasticity of the 

 cell-wall of the floating-cells enabling them to attach themselves 

 to the intestine, as we have seen them adhering to one another 

 and to the surface of the peritoneal cavity. Fourthly, from there 

 being floating-cells in the abdominal cavity of many Infusoria, 

 as well as in the stomach of Planaria and the Rotatoria, where 

 the sequence of development from the young cell with un- 

 coloured, to the older cell with coloured vesicles and bile-glo- 

 bules, is always present. And, lastly, from the free microscopic 

 Filarice that have come under my observation, both from the 

 salt- and fresh-water pools of the island of Bombay, having the 

 abdominal parietes of the peritoneal cavity covered with biliary 

 oil-globules as well as the intestine ; showing that, if the latter 

 are not derived from the former, both the abdominal as well as the 

 intestinal layer of the peritoneum are capable of producing them. 



If, then, we admit that the hepatic cells are derived from the 

 floating cells of Nais, then these cells are homologous with the 

 floating cells of the Infusoria, e. g. Nassula, Prorodon, Oto- 

 stoma, &c* 



* See "Spherical Cells," Ann. Nat. Hist. vol. xviii. p. 124, 1856. 



