408 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



juice is, therefore, of two kinds. Mechanically, it forms an emulsion 

 with the oil, while chemically it liberates the fatty acids with glycerin, 

 the formation of the emulsion being largely the result of the liberation 

 of fatty acids. 



(c) Action on Proteids. The action of pancreatic juice on proteids 

 coincides with that of gastric juice in so far that in both cases the con- 

 version is due to a ferment which is destroyed by heat, and that both 

 secretions convert proteids into peptones. Many points of contrast, 

 however, exist. In the first place, it was seen that gastric digestion 

 required the presence of dilute hydrochloric acid. In the case of pan- 

 creatic digestion it will be found that a half of 1 per cent, solution of 

 sodium carbonate produces the most active results. If a fragment of 

 .thoroughly boiled fibrin is placed in an artificial pancreatic juice, made 

 by adding a few drops of the glycerin-acetic acid extract to a 1 per cent, 

 solution of sodium carbonate, it will ultimately dissolve, but the process 

 will differ from that occurring in gastric digestion. After having 

 remained for an hour or two in contact with the pancreatic juice, the 

 fibrin will at first appear to be unaltered, but if it is stirred with a glass 

 rod, many small fragments dissolve, and on removing some of the larger 

 pieces and washing them with water, they are seen to be corroded and 

 as opaque as before, but not swollen and transparent, as would occur in 

 an analogous stage of gastric juice. Besides these superficial changes, 

 however, the properties of the fibrin have been considerably modified. 

 Undigested boiled fibrin is entirely insoluble in dilute acid, and if this 

 boiled fibrin, which has been partially digested by pancreatic juice, is 

 placed in a two-tenths of 1 per cent, solution of hydrochloric acid, it 

 will be rapidly dissolved, and form a solution of syntonin, which may be 

 precipitated by neutralization. Before being dissolved, therefore, boiled 

 fibrin is rendered by pancreatic juice more soluble in dilute acid than 

 even raw fibrin, which, as is well known, will not dissolve for many 

 hours. 



Again, in this stage of pancreatic digestion, the boiled fibrin becomes 

 soluble in a 10 per cent, solution of sodium chloride, and is readily 

 coagulated by nitric acid and boiling; it thus appears that the first step 

 in the pancreatic digestion of boiled fibrin is to change it to a soluble 

 albuminoid, somewhat resembling raw fibrin. 



Again, if the fibrin be allowed to remain in pancreatic juice until it 

 has been dissolved, a precipitate may be formed on neutralization which 

 is evidently of the nature of an alkali albuminate and analogous to the 

 parapeptone formed in gastric digestion ; while boiling will also produce a 

 precipitate, a phenomenon which is entirely unrepresented in any known 

 stage of gastric digestion. Although, as already mentioned, an alkaline 

 reaction appears to favor pancreatic digestion, nevertheless, it appears 



