HANCOCK ON TTTE ANATOMY OF DIB1UNCITTATE OErnALOPODA. 470 



the intestine is placed. The venous radicles of the abdominal walls 

 in the vicinity of the intestine migfet possibly abtotb the ehj Le ; bud 



fche anatomy of the parts shows nothing to warrant such an opinioiL 



After weighing this point with much care, I am foreed to the oou- 

 clusiun, which must have been generals* adopted when the macular 

 system in the Mollusca was thought to be complete, that the ab- 

 sorption is effected through the instrumentality of the intestinal veins 

 themselves, which are amply provided, and arc e\ cry way suitable, for 

 such a purpose. There are usually two or more such veins ; and in 

 the LoliginidcB they are placed symmetrically, on each side of the 

 alimentary tube, and have the portions which lie within the renal 

 chamber covered with glandular appendages, similar to those that 

 garnish the vena? cava?. They always open into the vena? cava?, or 

 into the great cephalic vein, close to the point where the latter gives 

 origin to the former, and are richly provided with twigs. 



Now, it would seem that it must be through the agency of the 

 capillaries of these vessels that the chyle, or nutritive fluid, finds its 

 way into the circulation. These capillaries probably penetrate to the 

 folds of the mucous membrane that lines the intestinal tube, and there 

 assuming the office of lacteals, in addition to that of veins, take up, 

 by a species of endosmosis, the nutritive products of digestion. Or, 

 it may be that, spreading out over the surface of this portion of the 

 alimentary tube, they there meet with and absorb the exuded chylous 

 fluid. 



There is nothing that should startle us in the idea that these 

 veins act in a double capacity, for everywhere throughout the animal 

 kingdom we observe one and the same organ performing several 

 functions, until the division of labour in organic life is fully con- 

 summated. And in the embryo of the higher animals the absorption 

 of the nutritive matters is actually effected by the sole agency of 

 the vascular system. Thus, in the embryo of the fowl, the yolk is 

 absorbed by the blood-vessels of the germinal membrane ; and the 

 nourishment of the mammalian embryo is accomplished by the aid of 

 the vascular tufts of the umbilical vessels, which likewise absorb the 

 required oxygen from the blood of the parent. So that, in the latter 

 case, these blood-vessels do not only act as lacteals, but also perform 

 the function of lungs. 



The chyle, then, in the Dihrancldate Cephalopoda appears to be 

 absorbed in this way by the intestinal veins, and to be poured by 

 them, mixed with the blood coming from the intestinal tube, into the 

 vena? cava?, and there commingled with the blood returning from all 

 parts of the system, to be subjected, on its way through the branchial 

 hearts to the aerating organs, to the action of the renal follicles. 



These hearts are of a very peculiar appearance ; so much so that 

 their cardiac nature has been denied. Their walls arc exceedingly 

 thick, soft and spongy, and are composed, for the most part, of 

 nucleated granular cells. On this account they are considered by 



VOL. I. — N. H. K. 3 Q 



