364 
POPULAR SCIENCE REVIEW. 
quently found a great mass of dead flies and other insects, which 
have been apparently lured into the pitcher by the secreted 
fluid ; and, their escape being prevented by a rim furnished 
with bristles pointing downwards below its mouth, have there 
miserably perished. It was determined by Dr. Hooker that the 
fluid is distinctly acid, and that it possesses the power, not 
merely of hastening the decay, but of actually digesting the 
bodies of the insects drowned in it. He also made the addi- 
tional remarkable observation that when removed from the 
pitcher and placed in a glass vessel, although still acid, it has 
entirely lost its power of digestion. This singular fact is in- 
terpreted by Mr. Darwin — and with great probability — to 
indicate that the actual agent in the digestion is a ferment of 
a nature similar to pepsin, which is secreted only during the 
absorption of some digestible nitrogenous substance. In the 
walls of the pitchers of Nepenthes are minute bodies resembling 
and possibly homologous to the “ quadrifids,” or rudimentary 
papillae of Genlisea or Pinguicula. 
To the last order, Sarraceniacese, belong the three genera Sctr- 
racenia , Darlingtonia , and Heliamphora , natives of America, 
also cultivated in this country under the name of “ Side-saddle 
plants.” The pitchers in this instance consist of the convoluted 
stalk of the leaf only, the blade forming the lid. They have not 
at present been subjected to the same careful examination as 
Nepenthes ; but, from the observations of Dr. Hooker, Dr. Canby, 
and others, there is little doubt that they will be found to pre- 
sent very similar phenomena. 
From the fact that the plants we have now passed under 
review belong to families very widely separated from one another 
on any system of classification, it is highly probable that phe- 
nomena of a similar character still remain to be discovered in 
other groups of the vegetable kingdom. Although, as we said 
at the outset, the assimilation of animal food by plants is no 
newly discovered fact, it must still be admitted that the series 
of observations here recorded — and especially the apparent pro- 
duction by vegetables of a digestive ferment performing all the 
functions of pepsin in the animal economy — form one of the 
most important and interesting additions to our knowledge of 
vegetable physiology that have been made for many years. 
EXPLANATION OF PLATE CXXVI. 
Fig. 1. Drosera rotundifolia ; natural size. 
Fig. 2. A leaf, x 2.J 
Fig. 3. A leaf, with imprisoned insect ; the tentacles partially inflected, 
x 4. 
