nap. VL DIGESTION. 123 
round the margins of the discs were a little inflected, and 
the secretion collected on the disc was acid, but the exterior 
tentacles were not affected. One leaf began to re-expand on the 
fourth day, and all were fully re-expanded on the sixth. The 
glands which had been in contact with the mucin were a little 
darkened. We may therefore conclude that a small amount of 
some impurity of a moderately exciting nature had been 
absorbed. That the mucin employed by me did contain some 
soluble matter was proved by Dr. Sanderson, who on subjecting 
it to artificial gastric juice found that in 1 hr. some was dis- 
solved, but only in the proportion of 23 to 100 of fibrin during 
the same time. The cubes, though perhaps rather softer than 
those left in water for the same time, retained their angles as 
sharp as ever. We may therefore infer that the mucin itself 
was not dissolved or digested. Nor is it digested by the 
gastric juice of living animals, and according to Schiff* it is a 
layer of this substance which protects the coats of the stomach 
from being corroded during digestion. 
Pepsin.—My experiments are hardly worth giving, as it is 
scarcely possible to prepare pepsin free from other albuminoids ; 
but I was curious to ascertain, as far as that was possible, 
whether the ferment of the secretion of Drosera would act on 
the ferment of the gastric juice of animals. I first used the 
common pepsin sold for medicinal purposes, and afterwards 
some which was much purer, prepared for me by Dr. Moore. 
Five leaves to which a considerable quantity of the former was 
given remained inflected for five days; four of them then died, 
apparently from too great stimulation. I then tried Dr. Moore’s 
pepsin, making it into a paste with water, and placing such 
small particles on the discs of five leaves that all would have 
been quickly dissolved had it been meat or albumen. The 
leaves were soon inflected; two of them began to re-expand 
after only 20 hrs., and the other three were almost completely 
re-expanded after 44 hrs. Some of the glands which had been 
in contact with the particles of pepsin, or with the acid secre- 
tion surrounding them, were singularly pale, whereas others 
were singularly dark-coloured. Some of the secretion was 
scraped off and examined under a high power; and it abounded 
with granules undistinguishable from those of pepsin left in 
water for the same length of time. We may therefore infer, 
as highly probable (remembering what small quantities were 
given), that the ferment of Drosera does not act on or digest 
* ‘Lecons phys. de la Digestion,’ 1867, tom. ii. p. 304. 
