DIGESTION AND RESORPTION 87 



The acidity of the gastric juice is about 05 per 

 cent of hydrochloric acid, and varies, according to 

 Khigine, from 0-56 for the soup given to 047 for 

 bread — for ox-tallow an abnormously low value of 

 0-4 was found ; the fats, except milk-fat, remain 

 nearly unchanged in the stomach. The strength 

 of pepsin in the gastric juice is very different, 

 about half as great for milk as for flesh or soup, and 

 a fifth of that for bread. 



The longer the time of digestion of a food-stuff 

 the more indigestible is it. Boiled flesh is about 

 10 per cent more easily digestible than raw flesh 

 (for dogs). If regard is paid to its great content 

 of water, which is indifferent to the digestion, milk 

 seems to be less digestible than flesh, and soup of 

 oats and flesh less digestible than milk. With milk 

 we observe the influence of eating as compared 

 with introduction through a tube. This depends 

 upon the slow secretion of gastric juice in the 

 beginning in this latter case. The difference is still 

 more pronounced in the figures for the quantity of 

 gastric juice, which runs nearly parallel to the time 

 of digestion. The slow digestion of coagulated 

 (boiled) egg-white is very pronounced. Boldyreff 

 has shown that fish needs about 30 per cent more 

 stomachical juice than horse-flesh. 



For bread Khigine has only one figure. London 

 and Polowzowa have varied the quantity of bread 

 given to their dog. The quantity of juice secreted 

 during the first three hours follows the square- 

 root rule. The high value of this quantity in their 



