36 ORGANS OF RESPIRATION, ETC. 



in contact with the water in the chamber becomes sack-like and 

 glandular. The pericardium and the sacks containing the testes 

 and ovaries, appear to communicate with the pallial cavity either 

 through these chambers or directly. 



The blood is a white liquid with a slight tendency to bluish, 

 and contains water 89 per centum, Albumen 3 per centum, Salts 

 and substances incoagulable b} T heat r5 per centum, Fibrine, etc., 

 *5 per centum. 



Valenciennes discovered in Nautilus three pairs of openings 

 connecting the branchial sack with five chambers ; of which the 

 anterior and posterior pairs situated on the sides of the rectum 

 are each provided with a single opening; whilst the fifth, a much 

 larger chamber, has an opening on either side. It is separated 

 by their walls from the other chambers ; and from the afieren 

 branchial veins which traverse these walls, lamellar appendages 

 project into the paired chambers, and pa pi Hated ones into the 

 single large chamber. In the smaller chambers are usually found 

 concretions of phosphate of lime, without trace of uric acid. 



The gills form a cylinder in Octopus and Sepia, and in Loligo 

 and other genera they are in the form of a half-cylinder: they 

 are two in number in the naked cephalopoda, as \\ell as those 

 possessing an internal shell ; and four, arranged a, pair on each 

 side, in the Nautilus : hence the terms Dibranehiata and Tetra- 

 branchiata, forming the highest divisions of the class Cephal- 

 opoda. The water finds access to the gills through the large 

 opening between the free anterior ventral margin of the mantle 

 and the body, and it is expelled from the funnel by a muscular 

 contraction of the wall of the mantle. 



The mantle is usually fastened dorsally by a niuseular neck- 

 band or nuchal band, to the head of the animal, and this band 

 may be either narrow or broad, or may even extend laterally 

 nearly around to the siphon : but usually t he ventral margin of 

 the mantle, at, least, is detached from the body : the degree of 

 attachment varies in the ditl'ereut genera. Within the mantle 

 opening are found the branchiae, the anus, , the openings of the 

 generative and urinating organs, and of the ink-bag. 



I'rinary openings are found on each side of the rectum. The 

 urine is deeidi -dly acid and limpid, and is tilled with myriads of 

 infusoria and a great quantity of aggregations of little crystals 



