680 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



Bunge has stated that it is this large amount of K in the food of 

 the herbivora that causes them to require so much NaCl. For when 

 potassium salts, the electro-negative constituent of which is other than 

 chlorine, such as carbonate, phosphate, or sulphate of potassium, come 

 into watery solution with NaCl at the body temperature they are partly 

 decomposed, both salts give up their acids, and, in addition to potassium 

 chloride, the carbonate, phosphate, and sulphate of sodium result through 

 double decomposition. If these K salts enter the alimentary canal they 

 are rapidly absorbed and meet with NaCl in the blood. As the above 

 interchange then takes place, the blood in attempting to preserve its 

 normal composition allows the new substances rapidly to diffuse away 

 through the kidneys. Consequently, through the taking in of potassium 

 sulphate, carbonate, or phosphate, the blood loses both Na and 01, and 

 this loss must be replaced by the ingestion of extra amounts of NaCl. 

 Consequently, herbivora, whose diet is rich in K salts, require more 

 XaCl than the carnivora. 



It is thus seen that the character and extent of the tissue changes 

 in starvation will be largely governed by the previous nutritive condition 

 of the animal. The following table, after Lawes & Gilbert, shows the 

 percentage of albumen, fat, salts, and water in the tissue of animals in 

 different conditions : 



2. THE NUTRITIVE PROCESSES IN FEEDING. (a) Feeding with Meat. 

 When animals are fed exclusively with fats or carbohydrates there is but 

 little difference in the metamorphosis of proteids other than is seen in star- 

 vation. So, also, exercise, water, and various other conditions are of little 

 influence. When, however, proteids are given with the food there is an 

 immediate increase in the amount of urea eliminated, for the albumen of 

 the food after being absorbed almost at once undergoes decomposition. 



Bischoff and Yoit found that a fasting dog which eliminated daily 

 twelve grammes of urea, when fed with twent3^-five hundred grammes of 

 meat eliminated one hundred and eighty-four grammes of urea daily ; 

 the destruction of albumen, therefore, increased more than fifteen fold. 



It would at first appear that if the same amount of albumen is 



