ORGANS OP SECRETION. 593 



itself sometimes in form of numerous isolated follicles, par- 

 tially divided internally by peripheral septa, and opening 

 separately into the hepatic ducts, as in sepiola, and some- 

 times in the more conglomerate form of distinct ramified 

 tubuli, forming isolated lobes of racemose bundles of dilated 

 follicles, opening by several common and slightly elongated 

 ducts, into the trunks of the hepatic ducts, and also directly 

 into the cavity of the third or spiral stomach, as in loligopsis. 

 The pancreas, therefore, exhibits nearly the same variable 

 character of development, and nearly the same connections 

 as in fishes, and corresponds with the more advanced condi- 

 tion of the salivary glands in cephalopods ; its connection 

 with the biliary duct is that common in the vertebrated 

 classes, and the cephalopodic type is repeated in the hepato- 

 pancreatic duct of the dolphin and some other mammalia. The 

 spleen, of which no trace has been detected in some of the 

 lowest cyclostome fishes, appears also to be deficient in this, 

 as in all the other invertebrated classes. 



The ink-gland, developed as a means of protection in 

 the naked cephalopods, and probably serving also as a 

 urinary apparatus, consists of a highly vascular, simple 

 cancellated sac placed on the ventral surface of the liver, 

 and terminating by a single wide fibrous duct, in or near 

 the anus, like the urinary and pigment-glands of gas- 

 teropods, and the anal or odour-glands of many verte- 

 brata. The dark-coloured gelatinous pigment secreted by the 

 parietes of the peripheral cells of this gland, and conveyed by 

 the expired water through the syphon, to be diffused, for 

 protection, through the surrounding element, corresponds in 

 colour with the changeable cutaneous coloured spots, but no 

 organic connection has been discovered between these dis- 

 tant parts. The ink-gland is deficient in the thick-shelled 

 nautilus, and present in the thin-shelled argonaula as in the 

 naked genera. The coloured secretion forming the changeable 

 cutaneous spots, appears to be confined to small, isolated, 

 highly expansible cells, situate on the vascular and sensitive 

 surface of the cutis, and beneath the soft layer of epidermis. 

 These small coloured cells continue to dilate and contract, 

 and thus to vary the colour of the surface, even on small 

 pieces of the skin detached from the body, and in the living 

 state they appear to be regulated by the will of the animal, 



PART VI. Q Q 



