546 Vines . — The Proteolytic 
every case there was a control digestion-experiment with 
unheated liquids: — 
(March i, '98.) Liquid heated to 70-80° C., for 15 minutes: 
digestion of fibrin (-05 grm.) not complete in 5 hours, though it 
eventually took place ; control-experiment, digestion complete in 
2f hours. 
(March 3.) Liquid gradually heated from 6o°-8o° C., maintained 
at 80° C. for 5 minutes, then allowed to cool : total time of exposure 
to heat, 1 5 minutes ; digestion not complete in 5 hours, but within 
20 hours; control, digestion complete within 2 hours. 
(March 8.) Liquid maintained at 8o° C. for 15-20 minutes: 
digestion not complete until morning of the fourth day (March 11); 
control, digestion complete within 3 hours. In a subsequent experi- 
ment (May 17) the effect of treating the liquid to 8o°C. for 20 minutes 
was less marked: in this case the time required by 10 cc. of the liquid 
to digest -05 grm. of glycerin-fibrin was just 24 hours. 
(March 15.) Liquid maintained at 78-83° C. for 30 minutes: 
digestion did not take place, although the experiment was continued 
for 4 days; in the control, digestion was complete in ij hour. In 
a subsequent experiment (March 19) I found that liquid which had 
been kept at 80° C. for 30 minutes gave no indication of digestive 
action on fibrin although the experiment was prolonged for a week ; it 
may be fairly concluded that the digestive power had been entirely 
destroyed. In the control, digestion was complete within 5 hours. 
With regard to the action of a boiling temperature (ioo°C.), 
I was surprised to find, on several occasions, that liquid boiled 
for some seconds did not lose its digestive power, though the 
rate of digestion was made very much slower. It seems, in 
fact, that to entirely destroy digestive power, the liquid must 
be kept at ico°C. for an appreciable time, say 3-5 minutes. 
Alkali . I have confined myself to the investigation of the 
action of sodium carbonate (Na 2 CO s ) upon the digestive 
activity of the liquid. The method of experiment was to 
add to a quantity (usually 5 or 10 cc.) of the pitcher-liquid 
an amount of the solid salt requisite to produce the desired 
degree of alkalinity : the alkaline liquid was then placed in 
the incubator, and maintained for any required time at any 
