304 jR. H. Chittenden — Papoid-digei^tion. 



d. Action on Raw Blood-fihrin. 



Fresh blood-tibrin washed for 18 or 24 hours with cold water until 

 perfectly white, was pressed as dry as possible and cut into moder- 

 ately small fragments. 



Each digestive mixture contained O'o gram papoid, 15 grams of 

 moist fibrin, and 50 c. c. of water together with the indicated per- 

 centage of acid or alkali. 



The 15 grams of fibrin contained 3 '4 161 grams of dry proteid 

 (110° C). 



The digestions were warmed at 40-45° C. for 8 hours. 



Weit;lit of 

 Reaciion. nndigesied residue. Raw fibrin digested. 



Neutral 1-9077 grams 44-1 per cent. 



0"04 per cent. Hydrochloric acid 1-4452 " 57-6 '• 



1-00 '-' Bicarb, soda 1-9469 '' 43-0 



A second series of experiments with raw blood-fibrin was tried, 

 especially to ascertain more fully the influence of an increase of 

 acid on the action of the ferment. The results, however, are not 

 only interesting as showing the effect of dilute acid, but are likewise 

 instructiye as showing the influence of dilution on the action of the 

 ferment. 



Each digestive mixture contained 10 grams of raw fibrin, 0*5 

 gram papoid, and 25 c. c. of water together with the indicated per- 

 centages of acid. 



The digestions were continued for 34- hours at 40-45° C. 



The 10 grams of moist fibrin contained 2-277 grams of dry proteid 

 (110° C). 



Weight of 

 Reaction. undigested residue. Raw fibrin digested. 



Neutral • 0-8982 gram 60-5 per cent. 



0-04 per cent. Hydrochloric acid 0-2452 " 89-2 



0-10 '- " •' 0-5270 " 76-8 



0-20 '= " " 1-6746 " 26-4 



These two series of experiments agree in showing a very marked 

 increase of digestive action in the presence of small amounts of 

 hydrochloric acid. Furthermore, the last series, especially, shows 

 that raw fibrin is particularly susceptible to the action of papoid, 

 both in a neutral and acid solution. In the last experiment, it is to 

 be noted that the digestions were continued for only 3^ hours, and 

 yet nearly 90 per cent, of the fibrin was dissolved in one case. This 

 is suggestive in view of the fact that raw blood-fibrin probably 

 comes nearest chemically to the so-called pseudo-membranes, such 



