DIGESTIVE SYSTEM. 331 
or Jess intimately connected with the digestive organs. ‘I'he 
first of these is the 
Spleen.—This organ is confined to the vertebral animals. 
In general it is single. In a few species, however, it is di- 
vided into several lobes. Its texture is vascular, consisting 
of a great assemblage of bloodvessels, united by a small 
quantity of cellular substance. It is covered externally by 
the peritoneum, beneath which there is another integument 
peculiar to it, which penetrates its substance along with the 
vessels, The arteries by which the spleen is supplied with 
blood, are, in general, branches from those of the stomach ; 
and the veins in which these terminate, ultimately pour 
their contents into the liver. In position, the spleen is, in 
some cases, connected with the stomach; in others, more 
itimately related to the liver, but united to both by means 
of its bloodvessels. 
The use of this organ in the animal economy remains to 
be ascertained. Though largely supplied with bloodvessels, 
it has no excretory duct, nor is its vascular, rather than 
glandular structure, favourable to the supposition that it is 
a secreting organ. Its lymphatic vessels are regarded by 
some as “* nowise remarkable for their number or size *;” 
while others assert, that they “ are both larger and more 
numerous than in any other organ +.” N 
It seems to be generally admitted, that the blood of the 
splenic vein is more fluid, and coagulates with greater diffi- 
culty than the blood in the splenic artery. Therefore, 
some change must have taken place on the blood in the 
spleen. By this change, the blood is probably prepared 
for the use of the liver, to which it flows. When the spleen 
has been removed from a dog, the cystic bile has been 

® Monro on Fishes, p. 37. 
+ Home’s Lect. on Comp. Anat. vol. i. p. 235. 
