91 DIGESTION OF ALBUMEN AND FLESH. 



into sugar; whilst protein bodies and fats were not affected in any appreciable 

 manner. Professor Lehrnann, however, attaches little importance to these experi- 

 ments performed by himself, from the fact that the fistulous opening was in the 

 lower portion of the ileum, and probably near the caecum. He adopts the experi- 

 ments of Bidder and Schmidt, and by an argument drawn from the amount of gas- 

 tric juice secreted in a given length of time, and the amount of protein substances 

 which it is capable of digesting, concludes that a large portion of flesh and albumen, 

 and the other protein bodies, pass out of the stomach undigested, and are finally 

 dissolved by the intestinal fluid. According to Professor Lehrnann, the amount of 

 gastric fluid secreted by a dog in 24 hours, equals one-tenth the weight of the whole 

 body. 100 grains of recent gastric juice are capable of dissolving from 3 to 5 grains 

 of coagulated albumen. A dog needs daily, for the perfect maintenance of all .the 

 physiological functions, 50 grains of flesh (containing 10 grains of albuminates) for 

 every 1000 grains of its weight. It secretes, however, only 100 grains of gastric 

 juice for every 1000 grains of its weight, only one-half the amount capable of 

 dissolving the albuminates of the flesh. Hence a large portion of the protein bodies 

 must pass out of the stomach undigested. 



Careful experiments have shown that the gastric juice is deprived in the duo- 

 denum, of its free acid ; and, with it, of its power of digestion by the bile and 

 pancreatic fluid. Hence other fluids must flow into the intestines, which are 

 capable of dissolving the protein bodies. 



The only method of deciding accurately upon the truth of these conclusions, 

 drawn by Prof. Lehrnann from the preceding argument, is to appeal to the 

 physico-chemical process of digestion, as it is performed in a normal condition in 

 the animal economy. 



I have enjoyed numerous opportunities of examining the contents of the sto- 

 machs of Fishes, Reptiles, Birds, and Mammals in every stage of the digestive 

 process, and have never discovered undigested particles of flesh in the small 

 intestines. The following observations were made during the prosecution of 

 various researches upon the blood, urine, relative weights of the organs, compara- 

 tive anatomy and minute structure of the organs of different animals, without 

 any reference whatever to the maintenance of an hypothesis. 



The stomach of an Alligator (Alligator Mmissippi&nsis) contained the bones, 

 teeth, hoofs, and hair of a pig. The flesh had been entirely digested, leaving the 

 bones as clean as those of a prepared skeleton. 



In the stomach of other alligators, we have found fishes, snakes, crabs, &c, in 

 different stages of digestion — some but slightly acted upon by the gastric juice, 

 others partially dissolved ; whilst of others, little more than their bones remained. 



The stomach of a Bullfrog (Sana ca(esbceana) , which had been captured twenty- 

 four hours, contained several Crawfish (Astacus Bartoni), and a slender Grass 

 Snake (Tropidonotus ordlnatus), about three feet in length. Although this food 

 had been swallowed for more than twenty-four hours, only the exterior parts of the 

 body of the serpent showed the evidences of the action of tbe gastric juice, and 

 the shell of the invertebrate animals was of a red color, resembling that which 

 they assume after they have been acted upon by boiling water. 



