212 CARBOHYDRATE-SPLITTING FERMENTS 



relate to the kinetics of fermentation, to make reference to 

 the comprehensive monographs which have appeared. 62 



Quantitative Determination of Diastase. Each advance 

 of our knowledge of the physiological role and importance of 

 the "carbohydrases," especially of the diastases, presup- 

 poses the possibility of their being quantitatively estimated 

 with reasonable exactness in animal fluids and tissues. In 

 a fluid this is not particularly complicated, aside from the 

 difficulty, which obtains in all fermentation investigations, 

 that it is impossible to estimate the ferments directly, 

 but only possible to determine them in terms of their active 

 strength. If a fluid containing diastase be treated with an 

 excess of soluble starch or glycogen solution, and after a 

 time the quantity of newly formed reducing sugar calculated, 

 an applicable measure of the activity of the ferment is 

 obtained. Because of the difficulties of detail attendant in 

 such a method there is need of methods capable of affording 

 a quicker means of orientation. The method of delle pro- 

 duction on a starch-paste plate, for example, has proved a 

 simple aid for this purpose in the study of diastasic fer- 

 ments. 63 In Pawlow's Institute, in imitation of the well- 

 known Mett method of estimating pepsin, the shortening of 

 starch cylinders (made by packing the starch in glass tubes) 

 has been employed for the same purpose. 64 A colorimetric 

 method devised by Wohlgemuth has, however, proved to 

 be the most useful of these measures; being based upon 

 the determination of the amount of ferment solution re- 

 quired to so change a known solution of starch, at given 

 temperature and length of time, that further bluing of the 

 solution will not follow when iodine is added. The tints ap- 

 pearing in serially arranged tests when iodine is added 



62 Literature upon Carbohydrate-splitting Ferments: F. Samuely, Handb. 

 d. Biochem., 1, 537-546, 1909; C. Oppenheimer, Die Fermente, 3d ed.; II, 66- 

 108, 1910; H. M. Vernon, Ergebn. d. Physiol., 9, 183-193, 1910; W. Biedermann, 

 Handb. d. vergl. Physiol., 2' 1397-1402, 1911. 



68 E. Muller, Centralbl. f . innere Med., 1908, 386. 



** Walter, cf . Pawlow, Arbeit, der Verdauungsdriisen, Wiesbaden, 1898. 



