DIGESTIVE SYSTEM. 263 



origin. To elucidate this structure, it has been likened to a 

 piece of sponge, or a honeycomb ; to which, if bloodvessels were 

 superadded, probably the general fabric bears some resemblance. 

 By regarding it as a spongy or porous body, we can account very 

 satisfactorily for the extreme variableness in ti)e magnitude and 

 weight of this organ ; for it is obvious that it will admit of great 

 latitude in its state of distention, and that its volume must greatly 

 depend upon the quantity of blood it may contain. It also pos- 

 sesses nerves, though they are but small; as well as absorbents, 

 which vessels are very numerous, and readily demonstrable by 

 injecting quicksilver under its peritoneal tunic. 



Oiganizalion. — This viscus receives its blood from the splenic 

 artery, a larae branch of the posterior aorta, which, in running 

 along the great curvature of the stomach, detaches numerous 

 short ramifications both to it and to the spleen. The splenic 

 veins, much larger than the arteries, unite with those of the sto- 

 mach, and form a vessel that largely contributes to the produc- 

 tion of the vena portse. Its nerves come from the coeliac plexus. 



Importance. — The magnitude and organization of the spleen 

 in the higher order of animals, together with the constancy of its 

 presence, are of themselves forcible arguments to establish its im- 

 portance in the animal constitution, though it would appear, from 

 some facts, not to be equally useful with other abdominal viscera; 

 for, if it be carefully extirpated, the animal will not only survive, 

 but thrive and do well : indeed, in the human subject, it has 

 been found after death so disorganized from disease, as to have 

 been apparently incapable of performing its function during life ; 

 and one case is related in which it was cut out without the indivi- 

 dual experiencing any great inconvenience from its loss. 



From the resemblance in general appearance and structure be- 

 tween this organ and those that are known to be glandular, very 

 diligent search has been made after an excretory duct: no ves- 

 sel of the kind, however, has yet been demonstrated, though, 

 more than once, have anatomists been led away with the idea 

 that they had discovered traces of one. Seeing, then, that the 

 spleen was without a duct (and, as was observed before, there is 

 no want of one, there being no secretion carried on), physiolo- 

 gists, compelled to relinquish the notion of its being a gland, 

 have attempted to explain its use from what appears to be a 

 faithful description of its structure, connexions, and relative 

 situation. 



OF THE PANCREAS. 



The pancreas or sweetbread is a glandular body lying across 

 the spine in the epigastric region. 



