on the Proteolytic Action of Pepsin-hydrochloric Acid. 99 
we find that, with like percentages of the two salts, ammonium oxal- 
ate has far the greater retarding power, and yet it is well known 
that the ferment acts well when combined with oxalic acid. More- 
over, our experiments show further on, that ammonium chloride has 
no greater retarding power than sodium chloride. Hence, there must 
be some reason, other than the one mentioned above, to account for 
all of the retarding action manifested by the oxalate. 
Petit* states, that the maximum digestive action of oxalic acid, 
with 0°2—0-4 per cent. of his pepsin, is attained with 0°5—4-0 per cent. 
of the acid, according to the amount of pepsin. 
The comparative digestive power of pepsin-oxalic acid and pepsin- 
hydrochloric acid is shown by the following experiments :f 
A. B. 0. 
HO sol. pepsin --.-- 50 ce. 50 c.c. 50 c.c. 
0°2 per cent. HOl.-.. 50 0 0 
Okina Ope te te a 0 0°5 gram. 1:0 gram. 
JB ly, O) 8 Sas ee 0 50 c.c, 50 ce. 
100 100 100 
01% HCl 0°5 % CoH2O. 1:0 4 C.H20, 
Warmed at 40°C. for 2 hours with 1 gram of pure, dry fibrin, the 
following results were obtained : 
A. B. C. 
Wt. of undigested residue --... 0°2170 04450 0°4371 
Per cent. digested .-.-.2------ 78°30 55°45 56:29 
A second series, with larger amounts of oxalic acid, gave the fol- 
lowing results: 
A. B. C. 
H,0 sol. pepsin--- 50c.c. : 50 ec. e. 50 ¢c. ¢. 
0-2 per cent. HCl. 50 0 0 
eta Og ese. 2 0 1°5 grams. 2:0 grams. 
ib (0) ee eee 0 50 c.¢. 50 ¢. ¢. 
100 100 100 
0-1 per cent. HCl 1°5 per cent. C.H.0,4 2°0 per cent. Cp H.04 
Undigested residue 0-1085 gram. 03090 gram. 0:3640 gram. 
Per cent. digested 89°15 69°10 63°60 
These four results being placed on the same basis, i. e. compared 
with their respective controls (100) show as follows: 
* Jahresbericht fiir Thierchemie, 1880, p. 309. 
+ Made in this laboratory by Mr. R. W. Pinney. 
