DIGESTIVE SYSTEM OP NAUTILUS. 577 



(1542.) From the crop, a short passage (fig. 289, u) leads into a 

 strong muscular gizzard (v) resembling that of a granivorous bird, and 

 lined in the same manner by a thick coriaceous cuticular layer : in this 

 gizzard, therefore, the food is gradually bruised and reduced to a pulta- 

 ceous magma. 



(1543.) At a little distance from the gizzard there is, in the Nautilus, 

 appended to the side of the intestine, a globular viscus (y), which is 

 hollow, and its cavity communicates freely with the intestinal canal. 

 The interior of this organ Professor Owen found to be occupied by broad 

 parallel laminae, puckered transversely, so as to offer a great extent of 

 surface ; and when examined under a lens, their structure was seen to 

 be follicular, and evidently fitted for secretion. The bile is poured into 

 this cavity, at the extremity furthest from the intestine, by a duct large 

 enough to admit a common probe. 



(1544.) In other genera this laminated viscus is represented by a 

 csecal appendage to the intestine, placed precisely in the same situation ; 

 and on opening it, its internal surface is found to be increased by a 

 spiral lamella that winds closely upon itself from one end to the other. 

 In such cases it is near the apex of the spire that the bile is received 

 from the liver ; so that in all essential particulars this spiriform viscus is 

 precisely analogous to the laminated cavity of the Nautilus. There can 

 be little doubt that this apparatus represents a capacious duodenum, 

 and that it is by the extensive surface afforded in its interior that the 

 nutritious portions of the food are separated, as neither the gizzard nor 

 the intestine itself presents an organization adapted to such a purpose. 

 With respect to its other uses Professor Owen remarks that its recep- 

 tion of the biliary secretion renders it in some measure analogous to a 

 gall-bladder ; but most probably its chief office is to pour into the com- 

 mencement of the intestinal canal a fluid which is necessary for the 

 completion of digestion ; so that, like the pyloric appendages of fishes, it 

 might be considered to be the representative of a pancreas. 



(1545.) The remainder of the intestine is a simple tube, which, after 

 one or two turns upon itself, mounts up to the base of the funnel, into 

 which it opens, and thus allows the excrement to be ejected to a distance 

 from the body. 



(1546.) The liver (fig. 289, z) is of very great bulk when compared 

 with the rest of the digestive apparatus. In Nautilus it is divided into 

 four distinct lobes, which are themselves made up of numerous lobules 

 of an angular form, each being invested with a very delicate capsule. 

 On removing the capsule every lobule is seen to be composed of nume- 

 rous acini, which with a needle may be readily separated into clusters 

 connected by the ramifications of their excretory duct. In other genera, 

 such as Octopus, wherein these acini have been minutely examined, 

 they have proved to be delicate cells or secerning caeca wherein the bile 

 is elaborated. The excretory canals derived from all the lobules of the 



2p 



