CHAP. III.] PRIMARY PRODUCTS OF DIGESTION BY TRYPSIN. 225 



allowed to set in, and in studying uncomplicated digestion by trypsin 

 it is now usual, according to Kuhne's directions, to employ salicylic 

 acid and thymol, agents which, in certain proportions, do not affect the 

 action of the pancreatic enzymes, whilst they absolutely check the 

 development of those organisms which are the essential cause of 

 putrefaction. We are thus able to study the process of the decom- 

 position of the proteids by trypsin, uncomplicated by the presence of 

 products of bacterial action. 



The primary The fi rst products of the action of trypsin upon the 

 products of proteids are, as has been already repeatedly stated, the 

 the action same as those which result from the action of acids and 



of trypsin. pepsin at a suitable temperature, to wit, herni-albumose 

 and anti-albumose, and these by the continued action of trypsin are 

 converted into hemi-peptone and anti-peptone. 



We have already pointed out that it is a characteristic of hemi- 

 peptone that under the influence of trypsin in alkaline media it 

 undergoes decomposition, yielding, in the first instance, such bodies 

 as leucine, tyrosine and glutamic acid, whilst anti-peptone absolutely 

 resists the action of trypsin and may thus be obtained with com- 

 parative ease free from all traces of hemi-peptone. 



Quantities "^ * s ^ ^ nterest to ascertain so far as possible the 



of products ob- quantities of the chief products obtained when a 



tainedinthe proteid is subjected to digestion with trypsin. One of 



decomposition the earliest of Kuhne's experiments furnishes us with 



this information - 



A quantity of blood-fibrin, corresponding to 382 grms. 



of the dried substance, was digested in 6 litres of water at a 

 temperature of about 40 C., in the presence of Na 2 C0 3 , through the 

 agency of chopped-up dog's pancreas weighing 55 grms. ; the solid 

 matter in the pancreas used was calculated to be 15*2 grms. At the 

 completion of the digestion it was found that 343*7 grms. of fibrin 

 had passed into solution. From the latter the peptone obtained by pre- 

 cipitation with alcohol amounted to 211*2 grms. ; further, there were 

 obtained 13*3 grms. of tyrosin and 31*6 grms. of leucin. In this diges- 

 tion the amount of peptone obtained amounted to 53 per cent.; the 

 leucine to 7*9 and the tyrosine to 3*3 per cent, of the combined water- 

 free fibrin and gland digested, whilst about 20 per cent, of other 

 unknown soluble products were formed. 



Normal Under the influence of bacterial action, as we shall 



trypsin diges- afterwards have to shew, the digestion of proteids by 



tion not asso- trypsin is associated with the evolution of large quanti- 



ciated with ties of inflammable and foetid gases. When however 



the evolution bacteria are excluded, the decomposition of proteids by 



of gases. . i .!* L .1 i . f i 



trypsm proceeds without the evolution of gases, as has 



been shewn by the researches of Hiifner 1 . This observer found 



1 Hiifner, 'Ueber ungeformte Fermente und ihre Wirkungen bei der Pankreas- 

 verdauung.' Journal fur prakt. Chemie, Vol. x. p. 1. 



(UNIVERSITY) 



V 



