Study of Autolysis by Physico-chemical Methods 7 



first splitting out and rendering soluble of the nucleic acid complex. 

 Only the autolytic changes which affect coagulable or insoluble 

 nitrogenous cellular constituents are shown, and the changes in 

 such substances as collagen or the other non-coagulable nitrog- 

 enous tissue elements are not brought out. In other words, the 

 ratio of coagulable and non-coagulable nitrogen in autolyzing tissues 

 shows only one of the many changes that are being accomplished 

 by the autolytic processes. 



On the other hand the freezing point determination gives an 

 absolute, delicate and reliable measure of the disintegration of the 

 tissue, since practically every step of this disintegration results in 

 an increase in the number of molecules in the solution. A freez- 

 ing point curve is, therefore, a correct picture of the total disin- 

 tegrative change that is taking place in the mixture, which a non- 

 coagulable nitrogen curve cannot well be. If we supplement the 

 freezing point curve with a conductivity curve we secure, in addi- 

 tion, information as to qualitative changes, for the conductivity 

 curve indicates only the increase in the number of free ions, which 

 we know are largely supplied by certain of the products of autoly- 

 sis, while the difference between the two curves gives us a measure 

 of the newly formed non-electrolytes. The information obtained 

 by these two methods is, therefore, much more instructive as to 

 the actual amount and rate of autolytic change than are the results 

 of coagulable nitrogen estimations, and in addition the methods 

 involved are much simpler and easier. A score of freezing point 

 determinations and a hundred conductivity measurements can be 

 obtained with no more expenditure of time and labor than one 

 nitrogen determination, and much smaller quantities of material 

 suffice — a point of great importance in many investigations. 



As a general rule the curves of conductivity increase and 

 freezing point depressions for the same tissue parallel each other 

 fairly closely ; at first the change in conductivity proceeds slower 

 than the change in freezing point, but later the conductivity con- 

 tinues to rise when the depression of freezing point has come nearly 

 to a standstill. This last phenomenon probably depends upon 

 the liberation of ammonia from the amino-acids and purines by the 

 amidases, and the formation of organic acids. Blood serum, 

 lymph and cerebro-spinal fluid show no evidence of autolysis by 



