GENERAL CONCLUSIONS. 



109 



appearance those of the triple phosphate. It is probable that the gland, not being 

 normally exercised, degenerated in structure. 



In the first of a series of experiments which have not as yet been completed, I 

 ascertained the correctness of M. CI. Bernard's statement that fatty substances are 

 not altered in the stomach or intestines of dogs if the pancreatic duct be tied. 



The abdominal cavity of a remarkably large and voracious pointer dog, noted for 

 his powerful digestive powers, was opened along the linea alba, and two fluidounces 

 of lard oil secured in the stomach by ligatures above and below, and one fluidounce 

 was injected and secured in the same manner in the intestines. The viscera were 

 then carefully returned and the wound sewed up. 



At the expiration of six hours the dog was killed, and the contents of the stomach 

 and intestines had neither increased nor diminished, and were changed neither in 

 physical or chemical properties, and the lymphatics of the mesentery did not appear 

 to contain any milky emulsion. Under the microscope, the lard oil presented an 

 appearance differing in no respect from that of ordinary oil. 



Lard oil was inclosed separately in the stomach and intestines of a dog, and 

 immersed for eighteen hours in the serum of this animal. At the end of this time 

 neither endosmose of the serum nor exosmose of the oil had taken place. In the 

 living dog the bloodvessels of the stomach and intestines retained their natural size 

 and appearance. When saline solutions of high specific gravity were enclosed in a 

 similar manner in the stomach and intestines of dogs and cats, the bloodvessels 

 were congested with blood, and the internal surface of the mucous membrane pre- 

 sented a pinkish-purple color. 



The following general conclusions have been drawn from this study of the com- 

 parative anatomy and physiology of the pancreas : — 



1. In the Invertebrate Animals, this gland and the lymphatic system do not 

 exist, because the character of the circulatory system, and the manner in which it 

 receives the digested matters from the visceral cavity, are such, that the conditions 

 requiring their presence are wanting. 



2. In Fishes we may study the development of the pancreas, the permanent 

 forms being but the transient conditions in the development of this gland in the 

 higher animals. 



3. The assertion of M. CI. Bernard, that the chief office of the pancreas is to 

 prepare fatty matters for absorption, is sustained by the following facts : — 



a. In the Garfish {Lepisosteus osseus), the emulsion of the tiitty matters takes 

 place in the duct and casca of the pancreas and their immediate vicinity, and no- 

 where else in the alimentary canal. 



h. The pancreas of carnivorous animals is relatively much larger than that of 

 frugivorous and granivorous ones. The amount of oil consumed by the former 

 is much greater than that consumed by the latter. It may be inferred from these 

 data, that the principal office of the pancreatic juice is the preparation of fats for 

 absorption. This is farther sustained by the fact that the size of the pancreas 

 amongst carnivorous animals is in a measure proportional to the amount of oleagin- 

 ous matters consumed. The pancreas of the active, voracious Garfish, which destroys 

 large numbers of small fish, is larger than that of the more sluggish fishes. 



c. The pancreas of carnivorous Chelonians fed upon vegetable matters, degener- 

 ated in its structure. 



