76 DROSERA ROTUNDIFOLIA. [Cuar. VI. 
“Quantity of fibrin digested in four hours by 10 cub. cent. of the 
liquid : 
“ Hydrochloric acid = me 0° 2915 
Propionic acid .. ae 0:1490 
Butyric acid -i z 0:1044 
Valerianic acid .. oC oc 0:0520 
“Comparing, as before, the three last numbers with the first taken 
as 100, the digestive power of propionic acid is represented by 16°8; 
that of butyric acid by 85°8; and that of valerianic by 17°8. 
“The mean of these three sets of observations (hydrochloric acid 
being taken as 100) gives for 
“Propionic acid... es z 15°8 
Butyric acid - PS = 32°0 
Valerianic acid .. es - 21°4 
«7. A further experiment was made to ascertain whether the 
digestive activity of butyric acid (which was selected as being 
apparently the most efficacious) was relatively greater at ordinary 
temperatures than at the temperature of the body. It was found that 
whereas 10 cub. cent. of a liquid containing the ordinary proportion of 
hydrochloric acid digested 0°1311 gramme, a similar liquid prepared 
with butyric acid digested 0°0455 gramme of fibrin. 
“Hence, taking the quantities digested with hydrochloric acid at 
the temperature of the body as 100, we have the digestive power of 
hydrochloric acid at the temperature of 16° to 18° Cent. represented 
by 44°95 that of butyric acid at the same temperature being 15:6.” 
We here see that at the lower of these two temperatures, hydro- 
chloric acid with pepsin digests, within the same time, rather less than 
half the quantity of fibrin compared with what it digests at the 
higher temperature: and the power of butyric acid is reduced in the 
same proportion under similar conditions and temperatures. We have 
also seen that butyric acid, which is much more efficacious than 
propionic or valerianic acids, digests with pepsin at the higher tem- 
perature less than a third of the fibrin which is digested at the same 
temperature by hydrochloric acid. 
I will now give in detail my experiments on the digestive 
power of the secretion of Drosera, dividing the substances 
tried into two series, namely those which are digested more 
or less completely, and those which are not digested. We 
shall presently see that all these substances are acted on by 
the gastric juice of the higher animals in the same manner. 
I beg leave to call attention to the experiments under the 
air fag: 
