312 PHYSIOLOGICAL CHEMISTRY. 



tion between the volatile and non-volatile acids varies with 

 the animal, but not regularly. 



It -is not possible to trace exactly the source of all these 

 acids, but apparently they come in part from a decomposition 

 of the sugar of the liver, since this is found to decrease as the 

 acid increases. Lactic acid may be formed first from sugar 

 and butyric acid from the lactic as in the bacterial fermenta- 

 tions. The appearance of hydrogen and carbon dioxide at 

 the same time favors this view. 



The Alteration in the Proteins. When subjected to asep- 

 tic auto-digestion, or to the same digestion with chloroform 

 or toluene, the protein substances gradually break clown into 

 simpler products. Among these the amino acids may be most 

 readily recognized; there is also an increase in the nitrogen 

 which may be distilled off with magnesia. The behavior here 

 is somewhat similar to that which follows in acid hydrolysis 

 of the proteins, or which occurs in prolonged boiling with 

 water under pressure; in both cases a kind of hydrolysis re- 

 sults and this may be what takes place in auto-digestion. 



In prolonged aseptic auto-digestion of the liver very con- 

 siderable quantities of leucine and tyrosine are formed ; on the 

 outer surfaces, where evaporation can take place, the latter 

 may even separate in crystalline bunches easily recognized. 

 The hexone bases and bodies of the xanthine group also result 

 but not always in very great quantities. 



Pathological Importance. This possibility of self-diges- 

 tion in the liver and other organs may help explain some of 

 the phenomena observed in pathological conditions. The 

 acids found sometimes in the urine as well as the leucine and 

 tyrosine have usually been traced to the liver. These experi- 

 ments show the rapidity with which such products may be 

 formed by a degenerative process. Pathologically the urine 

 sometimes shows a very high reducing power which cannot 

 be associated with sugar or uric acid or creatinine. The 

 liquid formed in the liver autolysis is always strongly reducing 

 in action and this may suggest an explanation for the obser- 

 vation on the urine. 



