330 A MANUAL OF PHYSIOLOGY 



possesses. Doubtless, a dog without a stomach will use to the 

 best advantage the digestive fluids that remain to him ; and the 

 pancreatic juice, with the aid of the bile and the succus entericus, 

 may be adequate to the complete task of digestion. So, too, a 

 man from whom the surgeon has removed a kidney, or a testicle, 

 or a lobe of the thyroid gland, may be in no respect worse off 

 than the man who possesses a pair of these organs. But what 

 do we deduce from this ? Not, surely, that the excised thyroid, 

 or testicle, or kidney was useless, or the gastric juice inactive, 

 but that the organism has been able to compensate itself for 

 their loss. Further, it would seem that the fate of the protein 

 or of part of the protein digested and absorbed by the stomach 

 is different from that digested and absorbed by the intestine. 

 For after the operation of gastro-enterostomy (the establish- 

 ment of an artificial opening between the stomach and the small 

 intestine through which the food passes rapidly without having 

 to submit to the challenge of the pyloric sphincter), the ingested 

 nitrogen is more quickly eliminated than when the protein is 

 first subjected to full gastric digestion. So that when the 

 quantity of protein in the food is increased above that neces- 

 sary for nitrogen equilibrium (p. 529) none of the excess is 

 assimilated and stored up, as is the case in a normal animal 

 (Levin, etc.). 



Pancreatic Juice. Pancreatic juice, bile, and intestinal juice 

 are all mingled together in the small intestine, and act upon the 

 food, not in succession, but simultaneously. But by artificial 

 fistulse in animals they can be obtained separately ; and occa- 

 sionally some of them can be procured through accidental fistulae 

 in man. It is said that under certain conditions, especially 

 when fat or oil is introduced into the stomach, the pylorus may 

 remain open long enough to permit the passage of pancreatic 

 juice or bile from the duodenum into the stomach, and this has 

 been recommended as a practical method of obtaining these 

 secretions in man. 



Human pancreatic juice, as obtained from a fistula, is a clear, 

 only slightly viscid liquid of distinctly alkaline reaction to 

 litmus. Its specific gravity is about 1007 to 1010. The total 

 solids constitute about 1-5 or 2 per cent., of which a little less 

 than i per cent, is made up of inorganic salts, chiefly sodium 

 carbonate, with small quantities of chlorides. The balance of 

 the solids consists mainly of proteins. The alkaline reaction 

 is due to the sodium carbonate, and it is worthy of remark, as 

 showing the important part taken by this secretion in the neutrali- 

 zation of the chyme, that when titrated against standard acid 

 the alkalinity of the pancreatic juice is not much less than the 



