PTYALINE. PANCREATINE. 89 



A nitrogenous substance, termed vegetable caseine, exists abundantly 

 in peas and beans, where it is known as " legumine." It is found 

 also in small quantity in oats, in the potato, and in the juices of many 

 plants. It resembles the caseine of milk in not being affected by a 

 boiling temperature, and in its coagulability by the organic acids and 

 magnesium sulphate. 



Ptyaline 



Is an ingredient of the saliva, to which it communicates the property 

 of converting hydrated starch into glucose. From this circumstance it 

 has sometimes been called "animal diastase." It differs from albumen 

 in many of its characters, and is not coagulated by nitric acid nor by 

 potassium ferrocyanide in an acidulated solution. On the other hand, 

 it is precipitated by alcohol in excess, and by a boiling temperature ; 

 but while, after precipitation by alcohol, it may be redissolved in water 

 with all its original properties, the action of heat produces in it a per- 

 manent alteration, and saliva which has once been boiled and allowed 

 to cool is found to have lost its power of converting starch. Ptyaline 

 can also be thrown down by adding to the saliva dilute phosphoric acid, 

 and afterward neutralizing the solution with lime water. The precipi- 

 tate of lime phosphate thus produced brings down with it the ptyaline, 

 which may afterward be redissolved in water, and again separately 

 precipitated by alcohol. Ptyaline does not constitute the whole of the 

 organic ingredients of the saliva, but is mingled in the secretion with 

 other albuminous substances. 



Fepsine 



Is the albuminous matter of the gastric juice, where it is found in the pro- 

 portion of fifteen parts per thousand. It is this substance which effects 

 the conversion of nitrogenous matters into albuminose in the digestive 

 process. It requires, however, in order to exert this action, to be dis- 

 solved in an acidulated liquid. It also causes the coagulation of caseine, 

 when first brought in contact with that substance. It is coagulated by 

 a boiling temperature, and when once subjected to the action of heat 

 loses permanently its digestive power. It is also thrown down by alco- 

 hol in excess, but may be redissolved in water after removal of the 

 alcohol. Pepsine is produced in the glandular follicles of the stomach, 

 and there mingled with the other ingredients of the gastric juice. 



Pancreatine. 



This is the characteristic ingredient of the pancreatic juice, where it 

 is very abundant ; being present in the proportion of a little over ninety 

 parts per thousand. It is coagulable by heat, nitric acid, alcohol, and 

 the metallic salts ; in these respects resembling albumen. But it is 

 also coagulated by magnesium sulphate, which has no effect on albumen. 

 It is further distinguished by the fact that, after precipitation by alcohol, 

 it may be again dissolved in water, and its solution exhibits the same 

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