THE DIGESTIVE ACTIVITY OF THE PANCREATIC JUICE. 305 



tract first affects milk-casein in such a manner that it is coagulated by 

 heat, after which it is peptonized. In other respects, trypsin has an 

 action like that of pepsin upon tissues containing albumin. 



Casein is almost wholly digested by trypsin. The tryptic ferment, which is 

 also present in the pancreas of new-born infants, is carried down mechanically 

 from the pancreatic juice diluted with water, by the production of a voluminous 

 precipitate, with collodion. The precipitate is washed and dried, and then the 

 collodion is dissolved out in a mixture of ether and alcohol. The residue is soluble 

 in water, and represents the ferment. Kuhne further separates with especial care 

 the albumin still combined with the ferment in the aqueous extract of the gland, 

 and thus secures the ferment in a purer form. It is soluble in water, insoluble in 

 alcohol and in pure glycerin. 



As trypsin is destroyed by hydrochloric acid, it is not advisable, as in the 

 presence of weakened digestion, to administer trypsin by the mouth. In a dried 

 state it can be heated to a temperature of 140 C. without injury; in a moist 

 state, if pure, to 50 C.; and mixed with salts or with albumoses and peptones, 

 to 60 C. 



Method: For testing trypsin, gelatin is especially useful, being liquefied in a 

 test-tube at the temperature of the body: 7 grams of gelatin boiled with 93 grams 

 of an aqueous solution of thymol. For antiseptic purposes thymol should be 

 added also, after nitration, to the fluid to be tested for the presence of the ferment. 



Trypsin results through the taking up of oxygen within the pan- 

 creas, from a mother- substance, zymogen, which collects in the interior 

 of the secreting cells in smallest amount between the sixth and the 

 tenth hour, and in largest amount, on the other hand, sixteen hours 

 after eating. It can be extracted from fresh glands by glycerin or by 

 water. In aqueous solution this body yields the ferment. Within the 

 excised pancreas the same result occurs on treatment with strong alcohol. 



The addition of bile, sodium chlorid. sodium glycocholate and carbonate, as 

 well as carbon dioxid, increases the activity of the ferment, while magnesium sul- 

 phate and sodium sulphate enfeeble its action. 



With continued action of the trypsin upon the hemipeptone pro- 

 duced, this is converted in part into the amido-acids: leucin (C 6 H 13 NO2), 

 tyrosin (C 9 H U NO 3 ), aspartic or amidosuccinic acid (C 4 H 7 NO 4 ) in the diges- 

 tion of fibrin and glutin, glutamic acid (C 5 H 9 NO 4 ), and butalanin or 

 amidovalerianic acid (C5H n NO 2 ). Gelatin-peptone, according to Nencki, 

 on further decomposition yields glycin and ammonia. The amido-acids 

 produced may be partly absorbed as such and may be consumed in the 

 circulation. 



The following bases also occur: xant bin-bases , lysin, lysatinin, argi- 

 nin, together with ammonia and a body that becomes reddened by 

 chlorin-water or bromin-water. 



If the action be continued still further, matters having a fecal odor 

 result, and with especial rapidity when the reaction is alkaline, also indol 

 (C 8 H 7 N), skatol (C 9 H 9 N), and phenol (C 6 H 6 O), volatile fatty acids with 

 the development of hydrogen, carbon dioxid, hydrogen sulphid, marsh- 

 gas and nitrogen. These products of decomposition, however, result 

 wholly from putrefaction of the preparations. This can be prevented 

 by the addition of salicylic acid or thymol, which destroys the putre- 

 factive organisms that are always present. 



Prolonged boiling of the albuminates with dilute sulphuric acid, like the action 

 of trypsin, produces first peptone, then leucin and tyrosin, and glycin from gelatin. 

 Hypoxanthin and xanthin result in this way on boiling fibnn, the former als( 

 from long-continued boiling of fibrin with wuti v r. 



Leucin, tyrosin, glutamic and aspartic acids, together with xanthm-bodies, 



