1881.] and Proteolytic Activity of Pancreatic Extracts. 161 



of preparations of the proteolytic enzymes. I venture to think that we 

 have in this method a means of estimating the activity of trypsin 

 preparations which is superior in ease and precision to any we possess 

 for the evaluation of pepsin preparations. What may be the limits of 

 error arising from inequalities in the composition of milk I am unable 

 to say, but with the same specimen of milk the limits of error do not 

 certainly exceed 6 to 8 per cent. 



The tryptic value of pancreatic extract from the pig, made on the 

 large scale, was found to range from 40 to 70 at 40° C. The pan- 

 creatic tissue of the ox and sheep yielded an extract which possessed 

 about the same tryptic activity as that of the pig. Extracts prepared 

 from single glands presented very considerable variations both in 

 regard to their diastasic and their tryptic activity. The following- 

 table shows the enzymic values of twelve samples of pancreatic extract 

 prepared with single glands from four pigs, four oxen, and four sheep, 

 killed for the market. 



Table IX. 



(All the observations were made at 40° C.) 

 CD stands for diastasic value, and T for tryptic value.) 



Kg. 



Ox. 



Sheep. 



*<•• * mr 



o JD = 100 



No. 3 | T=72 

 No 4 i" 1 ^ 100 



No " 5 {t=64 



-vr fl JB = 10 



No. 6 | T==50 



7 {t2% 



no. s 



No 9i D = 5 



no. u{5:jj 

 No. i2{?:^ 8 



It may be observed that the oscillations in the two enzymic values 

 bear no mutual relations to one another. 



The most appropriate standard of temperature for the valuation of 

 tryptic activity, is 40° 0., because this corresponds very nearly with 

 the temperature at which trypsin operates in the normal digestion of 

 warm-blooded animals. But it is more convenient to perform the- 

 testing at, or near, the ordinary temperature of the room (say, at 20°) 

 inasmuch as in the latter case, it is much less troublesome to main- 

 tain a continuously uniform temperature than at 40°. 



I have, therefore, taken some pains to ascertain the exact relation 

 between the value of T at 40° and at 20° respectively, and have found 

 that at 40° the value of T is very nearly three and a half times as 

 great as at 20°. If, therefore, the testing be performed at 20°, the 

 resulting value of T multiplied by 3 "5, will grve with sufficient 

 accuracy the value of T at 40°. 



