292 CONCLUDING REMARKS. 
[CHAP. XV. 
and the glands of one of them apparently absorb matter from 
captured insects, and certainly from an infusion of raw meat. 
There is, therefore, nothing anomalous in the Droseraceæ 
having acquired the power of absorption in a much more 
highly developed degree. 
It is a far more remarkable problem how the members of 
this family, and Pinguicula, and, as Dr. Hooker has recently 
shown, Nepenthes, could all have acquired the power of 
secreting a fluid which dissolves or digests animal matter. 
The six genera of the Droseracew have probably inherited 
this power from a common progenitor, but this cannot apply 
to Pinguicula or Nepenthes, for these plants are not at all 
closely related to the Droseracexw. But the difficulty is not 
nearly so great as it at first appears. Firstly, the juices of 
many plants contain an acid, and, apparently, any acid 
serves for digestion. Secondly, as Dr. Hooker has remarked 
in relation to the present subject in his address at Belfast 
(1874), and as Sachs repeatedly insists,* the embryos of some 
plants secrete a fluid which dissolves albuminous substances 
out of the endosperm ; although the endosperm is not actually 
united with, only in contact with, the embryo. All plants, 
moreover, have the power of dissolving albuminous or proteid 
substances, such as protoplasm, chlorophyll, gluten, aleurone, 
and of carrying them from one part to other parts of their 
tissues. This must be effected by a solvent, probably con- 
sisting of a ferment together with an acid.t Now, in the 
case of plants which are able to absorb already soluble matter 
from captured insects, though not capable of true digestion, 
the solvent just referred to, which must be occasionally 
present in the glands, would be apt to exude from the glands 
together with the viscid secretion, inasmuch as endosmose 
is accompanied by exosmose. If such exudation did ever 
occur, the solvent would act on the animal matter contained 
within the captured insects, and this would be an act of true 
digestion. As it cannot be doubted that this process would 
* ¢Traité de Botanique, 3rd edit. 
1874, p. 844. See also for following 
facts pp. 64, 76, 828, 831. 
+ Since this sentence was written, 
I have received a paper by Gorup- 
Besanez (‘Berichte der Deutschen 
Chem. Gesellschaft,’ Berlin, 1874, p. 
1478), who, with the aid of Dr. H. 
Will, has actually made the discovery 
that the seeds of the vetch contain a 
ferment, which, when extracted by 
glycerine, dissolves albuminous sub- 
stances, such as fibrin, and converts 
them into true peptones. [See, how- 
ever, Vines’ ‘Physiology of Plants,” 
p. 190.—F. D) 
