205 



Jess pure preparation may often answer, and various methods of 

 preparing such have been proposed, but we cannot describe all of 

 them. For the production of a glycerin extract the gland should 

 be rubbed with glass powder or pure quartz-sand, this mass care- 

 fully mixed with acetic acid of \% (1 cc. to each grm. of gland), 

 then for each part of the gland-mass add 10 parts of glycerin, and 

 filter after about three days. By precipitating the glycerin extract 

 with alcohol and redissolving the precipitate in water, we obtain a 

 solution which has a powerful digestive action (HEIDENHAIN). A 

 watery infusion of the gland may be made only after it has been 

 exposed to the air for 24 hours, and 5-10 parts of water for each 

 part by weight of the gland should be used. The simplest 

 method is to cut the gland fine and place it in a flask and allow it 

 to digest with water to which 510 cc. of chloroform (SALKOWSKI) 

 or ether has been added for each litre. After a few days we 

 obtain in this way a powerful infusion which keeps. 



The action of trypsin on proteids is best demonstrated by the 

 use of fibrin. Very considerable quantities of this albuminous body 

 are dissolved by a small amount of trypsin at 37-40 C. It is always 

 necessary to make a control test with fibrin alone, with or without 

 the addition of alkali. Fibrin is dissolved by trypsin without any 

 putrefaction; the liquid has a pleasant odor somewhat like bouillon. 

 To completely exclude putrefaction a little thymol, chloroform, 

 or ether should be added to the liquid. Trypsin digestion differs 

 essentially from pepsin digestion in that the first takes place in 

 neutral or alkaline reaction and not, as is necessary for pepsin di- 

 gestion, in an acidity of 1-2 p. m. HOI, and further by the fact that 

 the proteids dissolve in the trypsin digestion without previous ex- 

 pansion. 



Many circumstances exert a marked influence on the rapidity 

 of the trypsin digestion. With an increase in the quantity of 

 enzyme present the digestion is hastened at least to a certain point, 

 and the same is also true of an increase in temperature at least to 

 about -f 40 C., at which temperature the albumin is very rapidly 

 dissolved by the trypsin. The reaction is also of the greatest im- 

 portance. Trypsin acts energetically in neutral, or still better in 

 alkaline, solutions, and best in an alkalinity of 3-4 p. m. Na^O^ 

 Free mineral acids, even in very small quantities, completely prevent 

 the digestion. If the acid is not actually free, but combined with 

 albuminous bodies, then the digestion may take place quickly when 



