^ 252. 



THE CEPHALOPODA. 



289 



the stomach, the small intestine, the rectum, the branchiae, and the genital 

 organs ; the artery of these last, however, sometimes arises directly from the 

 heart. 



Nothing positive can now be said as to the terminal relations of these 

 arteries ; — that is, whether they are directly continuous with the venous 

 radicles by means of a capillary system with proper walls, or whether they, 

 terminate by orifices so that the blood is effused immediately into the paren- 

 chyma of the body.'"* 



The Venous system begins in the different parts of the body by numer- 

 ous small vessels, of which we are still ignorant whether they are continu- 

 ous with the terminal arterioles, or whether they commence by themselves 

 with proper orifices. Their radicles unite and form longer branches which 

 finally open into a large Sinus. One of these sinuses, which is of a circular 

 form, surrounds the upper extremity of the oesophagus, and receives the 

 veins coming from the eyes, the arms,*"^' and the parts of the mouth. From 

 this sinus arises another, of an oblong form, which, since it extends into 

 the cavity of the body and receives the different veins from the viscera, 

 may be called a Vena cava superior. In the centre of the body it divides 

 into two large venae cavae which extend on each side to the base of the 

 branchiae'*^' and terminate in the two so-called branchial hearts.'^' These 

 two veins receive, also, two trunks, which bring the blood from the mantle 

 and are often dilated into two large sinuses.*^"' 



The distinct, but often very thin walls of the venous sinuses, are some- 

 times so intimately blended with the adjacent organs, that these sinuses may 

 be easily taken for wall-less lacunae.'"' 



6 Milne Edwards and Valenciennes (loc. cit.) 

 throw no light on these questions. It is moreover 

 singular that in the numerous and often very de- 

 tailed figures of Del/e Cfiiaje of the vascular sys- 

 tem of Cephalopoda, he has nowhere represented 

 in the least a capillary net-work between the arte- 

 ries and vems ; while KbUiker (Entwick. der Ce- 

 phal. p. 81), declares that he has seen numerous 

 oapillary vessels in the embryos of Sepia. 



7 All the arms of the Cephalopoda have two 

 venous trunks. Lebert and Robin (Mailer's 

 Arch. 1846, p. 130) have observed, in the venous 

 system Sepia officinalis, a valve preventing the 

 reflux of the blood towards the head. 



8 With Nautilus, this sinus is divided into four 

 venae cavae (Owen, loc. cit.). 



9 The so-called Branchial hearts of the dibranch- 

 iate Cephalopoda have no muscular fibres, but 

 have a very glandular aspect, and are in close re- 

 lation with the urinary organs ; see below, § 255. 



10 Delle Chiaje, loc. cit. Tav. LXXXVIT. 

 LXXXIX. XCI. XCIII. (17, 27, 21, 23), has also 

 figured with many details the venous system of 

 Octopus, Sepia, and Loligo. 



11 ft is, therefore, difficult to decide if the large 

 cavities which Milne Edwards (Ann. d. 8c. Nat. 

 III. loc. cit. PI. Xm.-XVI.) has mjected, were di- 

 lated veins or simple lacunae. In this last case, 

 the venous system would communicate directly with 



25 



the cavity of the body, and there are many circum- 

 stances in favor of this view. It is, therefore, to be 

 regretted that Milne Edwards did not, in his re- 

 searches, pay more attention to the aquiferous sys- 

 tem which is spread through the whole body of 

 the Cephalopoda, and thus, for the present at 

 least, prevent the objection, that these aqueous 

 reservoirs should be confounded with the venous 

 sinuses. The lymphatic reservoirs which, according 

 to Erdl (^fViegmann's Arch. 1843, I. p. 163) sur- 

 round, and can be injected by means of the arteries, 

 are also, perhaps, venous sinuses. An observation 

 of Owen (On the Nautilus, p. 27, PI. VI. fig. 1, 

 No. 11, or Isis, p. 24. Taf. IV. or Ann. d.Sc. Nat. p. 

 121, PI. III. fig. 2, No. H), and of Valenciennes 

 (loc. cit. p. 287), that the large superior vena cava 

 communicates with the abdominal cavity by nu- 

 merous orifices, is of much importance. For, in this 

 way, this vein must be regarded as a large blood- 

 reservoir, conducting, very probably, the nutritive 

 fluid, after its tr.ansudation through the intestinal 

 canal, into the general blood current. 



The pericardium of the Cephalopoda sustains, 

 perhaps, analogous relations to the blood-system, 

 for, with Nautilus, it is said to communicate with 

 the abdominal cavity, and with the principal vena 

 cava, with the other Cephalopoda ; see the conclud- 

 ing paragraph of note 1, § 251. 



