168 



OF FOOD, AND THE DIGESTIVE PROCESS. 



a sort of budding forth of the alimentary canal at a particular spot upon 

 which a mass of cells has previously accumulated. The secretion of this 

 gland resembles saliva in its general appearance, being clear and colorless, 

 free from smell, alkaline in its reaction, and very viscid ; the only morpho- 

 logical constituents it contains are numerous granules of oil. Upon the ap- 

 plication of heat, or upon the addition of any of the stronger mineral acids, 

 it coagulates into a solid mass like the white of an egg. This appears to be 

 due to the presence of alkali-albumen and serum-albumen, as well as to a 

 peculiar form of albumen, which is precipitated in a gelatinous condition at 

 a temperature of 32 Fahr. from the concentrated secretion. 1 The proper- 

 ties of the secretion seem to vary according to the period of digestion at 

 which it is collected, being at first very tenacious and coagulating com- 

 pletely, and at a later period becoming thinner, more alkaline, and less per- 

 fectly coagulable by heat ; its solvent powers upon various constituents of 

 the food are, at the same time, less strongly marked. The composition of 

 the Pancreatic juice of the Dog is represented in the following Table; 2 the 

 term pancreatic including all the albuminous constituents: 



Leucin, Guanin, and Tyrosin, have been stated to be constant constituents 

 of the substance of the gland, and Leuciu and Xanthiu have occasionally 

 been found in the secretion. Recent experiments, however, 3 render it prob- 

 able that these substances proceed from the action of the secretion on the 

 albuminous constituents of the food, or even on the tissue of the gland 

 itself. 



119. The nature of the organic substance which forms so large a part of 

 the solid residue of the pancreatic juice, and which is so singularly prone to 

 decomposition, has not been accurately determined. Bernard states that it 

 resembles albumen in being precipitated by heat, acids, alcohol, and metal- 

 lic salts, but differs in being thrown down by sulphate of magnesia, and by 

 the circumstance that, after being precipitated by alcohol, it can be rcdis- 

 solved in water. The quantity of the secretion which is poured forth in 

 twenty-four hours, has been variously estimated ; and perhaps the differences 



i Wundt, Physioloejio, 1873, p. 217. 

 * (iorup-Besanez, Physiol. Cliomio, 1862, p. 487. 



3 Kiilmc, Centralblatt f. d. Mod. Wiss., 1807, p. 420, and Fudakowski, idem, 

 p. 540. 



