412 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



canal, the extent to which these processes take place can be scarcely 

 estimated; of course, the more proteid which is so broken up, the greater 

 will be the nutritive loss to the economy, since such putrefactive products' 

 have no physiological value. It may, therefore, be assumed that it is 

 only the excess of proteids which is so broken up, for under normal 

 conditions it may be assumed that peptone is absorbed as fast as it is 

 formed. In the case of the herbivora, whose long intestinal tract is 

 nearly always filled with residue of food, this decomposing process will 

 probably attain a higher degree than in the case of the carnivora. That 

 the intestinal contents are comparatively free from putrefactive odor in 

 these animals is not an objection to this statement, since it is always so 

 largely composed of cellulose and other non-putrefactive substances. 



It has been found that the amount of inclican contained in the urine 

 is a measure of the amount of putrefaction occurring in the intestine; 

 and since indican is present in the urine of herbivora in about twenty- 

 three times the amount found in the urine of man, it is evident that the 

 putrefactive process in the intestinal canal of the herbivora must be 

 also largely in excess. In addition to the fact that the proteids are 

 rapidly absorbed as soon as acted on by the digestive secretions, the 

 influence of the bile is also to be alluded to as a preventive of putrefaction. 



3. The Secretion of Pancreatic Juice. — In the pancreatic secretion 

 the digestive juices reach their maximum as regards intensity of action 

 and variety of food-stuffs on which they act. Human pancreatic juice 

 has never been obtained in a condition of purity, and were it not for the 

 studies made on animals this branch of our subject would be an empty 

 page. The volume of this gland, which is very constantly present and 

 subject to a great variety of changes, is much larger in the carnivora 

 than in the herbivora. In the herbivora the secretion is constant, in the 

 carnivora it is intermittent, while in the ruminant its maximum activity 

 appears to coincide with the end of rumination, when as much as two 

 hundred to two hundred and seventy grammes may be secreted per 

 hour. During fasting in the ruminant, although not absolutely sus- 

 pended, its secretion is greatly reduced in amount. In the horse, from 

 experiments made by Leuret and Lassaigne, Colin was able to determine 

 that the maximum hourly secretion was two hundred and sixty-five 

 grammes, or about the same as that of the ox, though part was probably 

 lost by not tying the supplementary ducts. As in the carnivora, so, 

 also, in the herbivora, this gland is extremely liable to inflammation, 

 which , of course, will affect the general result. 



Another method by which the amount of pancreatic secretion 

 poured out was estimated was to ligate the bile-duct and pylorus, then 

 empty the intestine by pressure, and then to tie its lower extremity. In 

 this way six hundred to one thousand grammes of clear, limpid fluid 



