on Amylolytic and Proteolytic Action. 141 
and thoroughly washed blood fibrin. All soluble matters are re- 
moved by successive extraction with boiling water, cold and boiling 
alcohol, and finally with cold and warm ether. The fibrin is thus 
obtained in a perfectly friable condition and can be easily ground to 
a coarse powder. It is then dried at 100-110° C, This materia! is 
well adapted for quantitative experiments with pepsin-hydrochloric 
acid; the residue remaining after a digestion can be rapidly filtered 
with the aid of a pump, and can be easily freed, by washing, from 
peptones and other soluble products of digestion. 
The gastric juice employed in the experiments, consisted of a 
hydrochloric acid solution of a glycerine extract of the mucous mem- 
brane from a pig’s stomach, in the proportion of 10 grams glycerine 
extract to 1 litre of 0:2 per cent. hydrochloric acid. 50 or 100 c.c¢. 
of this pepsin-hydrochloric acid were employed in each experiment, 
to which was added 1 or 2 grams of the dried fibrin (2 per cent.), 
together with the given percentage of bile or bile acids. 
We first tried the influence of bile itself, using fresh ox bile, 
slightly alkaline in reaction and containing 10°02 per cent. of solid 
matter. 
The digestive mixtures were warmed at 40° C. for two hours, then 
filtered at once, and the undigested residue washed thoroughly,* 
and dried at 100° C. until of constant weight. Following are the 
results of the first series of experiments, with 2 grams of fibrin and 
100 c. e. of gastric juice. 
Bile in Weight of Fibrin 
digestive mixture. undigested residue. digested. 
0 per cent. 0°1957 gram. 90-21 per cent. 
0°25 01890 90°55 
0°50 0°2050 89°75 
1:00 0°2234 88°83 
3°00 0°5453 72°73 
500 0°7642 61°84 
* In all of the pepsin-hydrochloric acid digestions the presence of bile or bile salts 
naturally causes more or less of “a precipitate, dependent in amount upon the percent- 
age of bile and also upon the amount of digestive products. In washing the undi- 
gested fibrin it was of course necessary to remove this precipitate. This was accom- 
plished by pouring over the precipitate on the filter 50 c. c. of 0°5 per cent. potassium 
hydroxide and then washing with water until the alkali was wholly removed. 
The following experiment shows that under these conditions the alkali affects the 
swollen fibrin but little, if any. Two portions of fibrin of 2 grams each were warmed 
with 100 c. c. of 0-2 per cent. HCl for 30 minutes, then filtered and one washed with 
water alone, the other with water and alkali. The first gave 1:9272 grams dried 
residue, the other 1°9155 grams. 
