172 ELEMENTARY PHYSIOLOGY. [XVL 



remove with blotting-paper the excess of 

 fluid, add five. times its bulk of glycerine 

 and place aside stirring occasionally. It is 

 best to leave the mixture for some days 

 before use, it may be kept almost indefinitely. 

 When required for use, filter through muslin, 

 add to the fluid ten to twenty times its 

 volume of HCl "2 p.c. and filter. 



Action of Gastric Juice. 



2. a. Take four test-tubes. In A place 5 c.c. of 

 hydrochloric acid "2 p.c. In 5 5 c.c. of 

 artificial gaStric juice. In (7 5 c.c. of the 

 same juice, carefully neutralized with dilute 

 NajCOj. In D .5 c.c. " of the same juice, 

 thoroughly boiled. Add "the same quantity 

 of fibrin' to «ach, and place! in a water bath 

 at about 37° 0. Examine from time to time. 



A, the fibrin will swell up and become trans- 

 parent, but will not be dissolved; on neu- 

 tralization it will appear unaltered. 



B, the fibrin will be digested. 



C, the fibrin will be unaltered. 



D, the fibrin will be like that in A. 



1 Eaw fibrin digests more easily than that which has been boiled 

 or kept in alcohol, it often however contains traces of pepsin so that 

 a slow digestion may take place when acid only is added to it. When 

 it is required to measure accurately the amount of fibrin added, raw 

 fibrin finely chopped up should be placed in dilute HCl until it is 

 well swollen, the excess of acid poured off and the fibrin measured in 

 small tubes containing (e.g.) 2 c.c. 



