ACTIVITY DURING DIGESTION. 27 



ance, and that the white of the hen's egg is of sufficiently constant com- 

 position to be employed as a test object for the purpose. The law of 

 .Schiitz and Borrisow applies also in its full extent to the action of 

 tiypsin. 



The methods of comparing the working of other ferments are less 

 perfect, and in our experiments have been, and still are, frequently 

 modified. The activity of the amylolytic ferment of the pancreas was 

 for a long time determined in the laboratory by titrimetric estimation, 

 after the method of Fehling, of the sugar, which is formed from a given 

 quantity of starch paste exposed under certain conditions to the activity 

 of the ferment. The number of milligrammes of sugar produced, served 

 as a measure of the amylolytic activity. This method furnished good 

 and reliable results, but necessitated a great expenditure of time, and 

 was, therefore, not wholly satisfactory in a research where numerous 

 estimations were required. Hence a more rapid one was sought for, 

 and recently an attempt was made by the laboratory (I)rs. Glinski and 

 Walther) to estimate the activity of the proteolytic and amylolytic fer- 

 ments of the pancreas by analogous methods. Thin glass tubes were 

 filled with coloured starch paste and then exposed in the thermostat to 

 the action of the ferment for a certain period, usually for half an hour. 

 The paste was dissolved from the ends inwards, the limit of ferment- 

 action, thanks to the colouration, being clearly visible. As in peptic 

 digestion, the length of the digested column was measured and ex- 

 pressed in millimetres. From numerous experiments with artificial 

 solutions of ferment (pancreatic juice diluted twice, thrice, Arc.) the 

 relationship between the quantity of ferment and the length of the 

 dissolved column of starch has been established. The law of Schiitz 

 and Borrisow is valid here also to its full extent i.e., the content of 

 ferment in the fluids, varies with the square of the length of the 

 column of digested starch measured in millimetres. The activity of 

 the amylolytic ferment will therefore be expressed in both ways in tin- 

 experiments given below, viz., in terms of the milligrammes of sugar 

 formed, and also in that of the number of millimetres of starch-column 

 dissolved. 



Unfortunately all attempts to base an evaluation of the fat-splitting 

 ferment upon the same system have, up to the present, remained fruitless, 

 and we had finally to set to and determine by titration with baryta 

 solution, the acidity of the permanent emulsion formed by fat and 

 pancreatic juice, after it had stood for a certain time (with periodic 

 shaking) at a given temperature. The number of cubic centimetres of 

 baryta solution which were necessary for the neutralisation of the fat 

 acids, served as measure of the activity of the fat-splitting ferment. 

 But naturally our failure will not prevent us from endeavouring to 



