$°6 PHILOSOPHY OF ZOOLOGY. 
mencement of the intestinal canal. In this cavity the chyme 
is destined to be mixed with other secretions, before it be 
rendered fit to be taken up for the use of the circulation. 
These are the pancreatic juice and the bile. 
The pancreas is a large conglomerate gland, bearing a 
very close resemblance in its texture and secretions to the 
salivary glands. In the different vertebral animals, it exhi- 
bits remarkable modifications of size, colour, consistence and 
form. It is destined to prepare the pancreatic juice. This 
liquor is collected in the gland by small radicles, which gra- 
dually unite, to form the excretory ducts. These last some- 
times unite with the bihary ducts ; im other instances they 
continue distinct, and pour their contents into the duodenum. 
In some animals the stomach itself receives the fluid. 
Sometimes there is but one opening, in other cases the 
ducts are as numerous as the lobes or the divisions of the 
gland. The excretion from the ducts is promoted by pres- 
sure and stimuli. 
The nature of this juice has not been satisfactorily ex- 
amined. It is, by some, considered as similar to the sali- 
va; by others, as of the nature of the gastric juice. It 
likewise remains to be ascertained, what effeets are produ- 
ced on the chyme by its presence, whether it acts chemi- 
cally asa solvent, or, by assimilating it nearer to the nature 
of the blood, renders it more fit for being absorbed and 
mixed with that fluid. The other organ which is concern- 
ed in the process of chylification, is the 
Liver. —'Vhis gland exists in all those animals which are 
furnished with a heart and circulating system. It varies 
greatly in form, size and subdivisons; but in all cases 
there isa very striking analogy in structure, colour and 
consistence. It receives an artery im the mammalia, term- 
ed the hepatic ; and a vein which likewise terminates in its 
substance. his last circumstance is peculiar to this gland. 
