26 



THE OCTOPUS. 



and organs of hearing and taste, besides those which are ap- 

 parent on its exterior, namely, of sight and touch. Instead 

 of having "no blood," it is furnished with a complete circu- 

 latory apparatus consisting of one systemic and two branchial 

 hearts, arteries which distribute the blood through all parts of the 

 body, and a system of veins or canals by which it returns towards 

 the gills, of which breathing organs the animal has two — one on 

 each side. By the alternate expansion and contraction of the 

 bladder-like mantle-sac — an action resembling that of a pair of 

 bellows — the water is pumped into contact with these gills, which 

 convey to the blood the oxygen contained in it ; and when its 

 life-giving, purifying gas has been extracted from it, it is expelled 

 by the muscular, valved funnel, or syphon tube, which has also 



another function, to be 

 presently described. Far 

 from being " a skin with 

 nothing inside it," from 

 the beak and mouth (within 

 which is a tongue like a 

 rasp, having recurved spines 

 or teeth) is continued the ali- 

 mentary canal, oesophagus, 

 crop, gizzard, stomach, and 

 intestines; and within this 

 so-called " empty pouch " 

 are also the liver, and the organs of reproduction and respiration. 

 The " tentacles," or arms, cannot be " turned inside out Hke the 

 fingers of a glove." On making a section across one of them, it 

 will be seen that it is composed of close muscles, the fibres of 

 some of which run longitudinally, and others transversely. The 

 arm, therefore, is more like the strong flexible lash of a stout 

 hunting whip than the finger of a glove, and is solid, except that 

 it has a perforation along the centre of its axis for the lodgment of 

 its nerve and artery. 



Fig. 4. Tongue of the Octopus [O. 

 Magnified 12 diameters. 



nilga7-is). 



