10 4 PHYSIOLOGY OF PANCREAS. 



tions or lobes, united by a slender isthmoid portion. In some individuals it is 

 single, and in others consists of three lobes. From each lobe an excretory duct is 

 given off, which terminates separately in the intestine near the opening of the 

 biliary canals. The color and appearance are similar to those of the well-developed 

 pancreas in all animals, cold or warm-blooded, and so constant in this respect are 

 the different glands in vertebrate animals that any one familiar with comparative 

 anatomy and physiology can distinguish them at a glance. 



The pancreas of the omnivorous and carnivorous Mammalia resembles, in appear- 

 ance and structure, that of Man ; its secretion enters the duodenum at the same 

 point as that of the liver. In the Apes, the Ruminantia, and most Carnivora and 

 Rodentia, it has but one duct which usually unites with the biliary. In some 

 animals— as the Horse, Hog, Otter, and Beaver — it has two ducts, one of which 

 unites with the biliary duct, and the other enters by itself, further behind, into the 

 duodenum. In the Rabbit, the biliary and pancreatic ducts are separated from 

 each other by a considerable interval. 



The pancreas of all the carnivorous Mammalia which I have thus far examined 

 is much larger than that of the frugivorous ones. This illustrates an important 

 physiological fact, which will be shown by numerous comparative weights of the 

 organ accurately ascertained. 



Having considered the development, structure, and comparative anatomy of the 

 pancreas in the four great classes of vertebrate animals, we shall next consider its 

 use in the animal economy. 



Although Mayer, Magendie, Tiedemann, Gmelin, Leuret, Lassaigne, and other 

 physiologists and chemists had investigated the physical and chemical properties of 

 the pancreatic fluid, still one of its important offices was entirely unknown until 

 the researches of M. CI. Bernard 1 demonstrated that it is indispensable for the 

 formation of chyle and the absorption of fatty matters. Previous to this discovery, 

 it was considered similar to the fluid secreted by the salivary glands, and its prin- 

 cipal use was affirmed to be the conversion of starch into glucose. The investiga- 

 tions of M. CI. Bernard demonstrated that the limpid chyle (formerly called vege- 

 table chyle) is the product of the digestion of materials which contain no fatty 

 matters, and the white chyle (called formerly animal chyle) contains fatty 

 matters in the state of an emulsion, and the lymphatics of the mesentery are found 

 to contain a white milky fluid only after the absorption of fatty matters, and that 

 this emulsion and modification of the fatty matters were effected by the agency of 

 the pancreatic juice. These conclusions were derived from the results of numerous 

 ingenious experiments. 



If Dogs are fed upon oleaginous matters, and killed at different periods, oil will 

 be found unaltered until it comes in contact with the pancreatic fluid, and if the 

 pancreatic ducts be tied, all alteration is prevented, and the oil remains transparent. 



The most conclusive and beautiful of all Dr. Bernard's experiments were per- 

 formed upon the Rabbit. In this animal, the pancreatic duct opens into the intes- 



1 Annales des Sciences Natur. Sept. 1848. 



