288 



THE CEPHALOPODA. 



-^^ 251, 252. 



CHAPTER VII. 



CIRCULATOKY SYSTEM. 



§ 251. 



The circulatory system of the Cephalopoda does not appear more highly 

 developed than that of the other MoUusca.^" However, this subject is still 

 deficient in creditable observations, and especially in those relating to the 

 absence of completely-closed vessels. 



The blood is usually colorless, or of a green-bice, or violet-bice color, and 

 contains, proportionably, numerous round corpuscles enclosing many gran- 

 ules most of which are colorless, but with a few, scattered here and there, 

 of a violet hue.^-> 



§ 252. 



The Central organ of the circulation consists, with all the Cephalopoda, 

 of a simple ventricle, situated in the centre of the cavity of the body, and 

 surrounded with a pericardium. It is round, or oblong,'" and serves as an 

 aoi'tic heart. 



With Nautilus (Tetrabranchiata), this organ receives, on each side, 

 two branchial veins ; while with the Dibranchiata there is one vein 

 only, and the heart sends off a superior and an inferior aortic trunk. <-> The 

 mouth of the veins and the origin of the arteries are furnished with 

 valves.® The Ascending aorta first sends two branches to the mantle, 

 then gives oif branches to the liver, to the upper portion of the digestive 

 canal, to the inferior salivary glands, and to the funnel. I3ehind 

 the cephalic cartilage it bifurcates, forming a ring embracing the 

 upper extremity of the oesophagus, and from which arise two arteries for 

 the ocular bulbs, '■*' eight or ten for the arms, and many small branches 

 for the parts of the mouth. ^'^ The Descending aorta furnishes branches to 



1 See Milne Edwards, and Valenciennes, 

 Compt. rend. XX. 1845, p. 261, 7.50, or Frnriep's 

 neue Notiz. XXXIV. p. 84, 2.58 ; also Milne 

 Edwards, Ann. d. Sc. Nat. III. 1845, p. 341. 

 This last author has also described (Ann. d. Sc. 

 Nat. VIII. p. 5o), the circulatory system of the 

 Loligina, wliich is interru]ited by a large sinus ; 

 but he makes no mention of the aquiferous system. 

 As of late there is increasing evidence for the 

 opinion, that, with various invertebrate animals, 

 the blood-system communicates externally at cer- 

 tain points on the body, and can tlierefore receive 

 water into its interior, it is now important to inves- 

 tigate the direct or indirect relations between this 

 and the aquiferous system which is so widely 

 spread through the Mollusks, the W'orras and the 

 Zoophytes. It may be that this aquiferous system, 

 if it really communicates with the blood system, 

 corresponds to a lymphatic apparatus, although it 

 seems hardly reasonable to suppose that canals, 

 whicli carry a portion of the nutritive fluids, should 

 open externally.* 



'i IVasner, Zur vergleicb Physiol, d. Blutes. 

 nft. I. p. 19 ; and Dclle Chiaje, Discriz. I. p. 57. 



1 The form of the heart depends upon that of the 



posterior part of the body ; it is large in the gen- 

 era with a short body, and el<mgated in those of a 

 long body. According to Kolliker (Ann. of Nat. 

 Hist. XVI. p. 414), Hectocoiylus has also a 

 heart communicating with arteries and veins, but 

 he says nothing of its lot^ality. 



2 See Oicejz, On tlie NautUus, PI. VI. fig. 1, or 

 Isis, Taf. IV. or Ann. d. Sc. Nat. XXVIII. PI. III. 

 fig. 2 ; Brandt, loc. cit. Taf. XXXII. fig. 22 ; The 

 Catal. of the Physiol. Ser. II. PI. XXII. (Sepia) ; 

 and Fan Be.neden, loc. cit. PI. III. fig. 5 (Ar- 

 /^onauta). 



Often the two branchial arteries are widely di- 

 lated before entering the heart, and Jhese dilata- 

 tions may be regai-ded as auricles. 



3 See Cu-vier, Mtm. p. 22, PI. H. fig. 4 (Octo- 

 pus) ; and Owen, Cyclop. I. p. 541, fig. 227 

 (Onychoteuthis). 



4 For the distribution of the ophthalmic arteries 

 see Krohn, Nov. Act. Nat. Cur. XIX. pt. U. p. 

 47. 



5 Delle Chiaje, loc. cit. Tav. LXXXVin. XC. 

 XCII. XCIV. (or 20, 28, 22, 24) has represented 

 in detail the arterial system of Octopus vulgaris. 

 Sepia officinalis, Loligo vulgaris and sagittata. 



* [ § 251, note 1.] 

 (Octopus). — Ei). 



For Milne Edwards^ beautiful figures see R^gne anim. loc. cit. PI. 1'', 1 



