3?6 PHILOSOPHY OF ZOOLOGY. 



mencemenl of the intestinal canal. In this cavity the chyme 

 is destined 10 be mixed with other secretions, before it be 

 rendered n't 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 si/e, 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 biliary ducts ; in 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 of 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 effects are produ- 

 ced on the chyme by its presence, whether it acts chemi- 

 cally as a 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. This 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 is a very striking analogy in structure, colour and 

 consistence. It receives an artery in the mammalia, term- 

 ed the hepatic; and a vein which likewise terminates in its 

 substance. This last circumstance is peculiar to this gland. 



