DIGESTIVE ORGANS OF FISHES. 221 



organs is very complicated ; for they are pro- 

 vided with a crop, a muscular gizzard, and a 

 caecum, which has a spiral form. In these ani- 

 mals we also discover tlie rudiment of another 

 auxiliary organ, namely, the Pancreas, which 

 secretes a fluid contributing to the assimilation 

 of the food. This organ becomes more and more 

 developed as we ascend in the scale of animals, 

 assuming a glandular character, and secreting 

 a watery fluid, which resembles the saliva, both 

 in its sensible and chemical properties. It has 

 been conjectured that many of the vessels, 

 which are attached to the upper portion of the 

 alimentary canal of insects, and have been 

 termed hepatic, may, in fact, prepare a fluid 

 having more of the qualities of the pancreatic 

 than of the biliary secretion. 



The alimentary canal of fishes is in general 

 characterised by being short ; and the con- 

 tinuity of the stomach with the intestines is often 

 such as to offer no well marked line of distinc- 

 tion between them. The cseca are generally 

 large and numerous ; and a number of tubular 

 organs, connected more especially with the 

 pylorus, and called therefore the pyloric appen- 

 dices, are frequently met with, resembling a 

 cluster of worms, and having some analogy, in 

 situation at least, to the hepatic or pancreatic 

 vessels of insects. Their appearance in the 



