20 THE WORK OF THE DIGESTIVE C! LANDS. 



digestion of the proteid columns, at least within the first ten hours 

 (employing the fluids which we have to deal with) is directly proportional 

 to the length of the period. This was the case even when the fluid 

 possessed its highest digesting power. These experiments did away 

 with the very natural mistrust that the solution of the proteid may 

 proceed at varying rates at different depths of the tubes, dependent 

 upon more or less stagnation of the digestive products within the lumen. 

 It may therefore be accepted that the length in mnis. of egg-white 

 dissolved by the several juices in a certain time, gives us an exact rela- 

 tive measure of the digestive power of the fluid. In the researches of 

 Borrisow, carried out upon this question in the laboratory of Pro- 

 fessor Tarchanoff, the relationship which lies at the basis of the connec- 

 tion between the length of the digested column of egg-white and the 

 pepsin contents of the fluid under investigation, came out with perfect 

 clearness. The following is the rule which expresses it, viz., the quantity 

 of pepsin in the compared fluids is proportional to the square of the 

 rapidity of digestion i.e., to the square of the column (expressed in 

 millimetres) which the juices are capable of digesting in the same 

 period of time. An example in figures will make this clear. If 

 one of the fluids digests a column of 2 mm. of proteid, and the other a 

 column of 8 mm., the relative quantity of pepsin in each is not 

 expressed by the figures 2 and 3 respectively, but by the squares of 

 these numbers i.e., by 4 and 9. The difference is instructive. According 

 to linear measurement, we should have in the second fluid one and a 

 half times more ferment, but according to our rule of squares, the 

 second fluid is two and a quarter times stronger than the first. 

 This rule has, of course, been deduced from comparisons made with 

 numerous artificial solutions of pepsin exactly prepared. Moreover, 

 the result which Dr. Borrisow arrived at independently, had already 

 been discovered before him, by Schiitz, from polarimetric estimation 

 of the amounts of peptone formed during the digestion of egg-white. 

 This correspondence in the data furnished by different methods affords 

 strong assurance of the correctness of the rule. I must here express 

 my regret that the method of Mett, which was published so long ago as 

 the year 1889, has not been as widely employed as it in reality deserves. 

 How easily could it be made a universal means of comparing proteid 

 digesting ferments, so that investigations upon these ferments would be 

 comparable with each other ? No one will deny that this is desirable in 

 a high degree, for then all observations on the juices of different 

 animals and men would be represented upon a uniform scale, which 

 would lead to important deductions concerning variations of ferment in 

 the individual, the species, and the genera. .We have still to add that 

 the diameter of the tube, even within wide limits, is without import- 



