268 CONCLUDING REMARKS. [Cuar. XIV. 
portions, bearing quadrifid processes; for these surfaces must 
be liable to be irrigated by foul water flowing from the 
concavity of the leaf when it contains dead animals.* This 
would follow from various causes,—from the gradual con- 
traction of the concavity,—from fluid in excess being secreted, 
—and from the generation of bubbles of air. More observa- 
tions are requisite on this head; but if this view is correct, 
we have the remarkable case of different parts of the same 
leaf serving for very different purposes—one part for true 
digestion, and another for the absorption of decayed animal 
matter. We can thus also understand how, by the gradual 
loss of either power, a plant might be gradually adapted for 
the one function to the exclusion of the other: and it will 
hereafter be shown that two genera, namely Pinguicula and 
Utricularia, belonging to the same family, have been adapted 
for these two different functions. 
* [Duval-Jouve’s observations 
throw some doubt on this point. He 
has shown (‘Bull. Soc. Bot. de 
France,’ t. xxiii. p. 130) that in the 
lar structures are described by Duval- 
Jouve as occurring on the leaves of 
Callitriche, Nuphar luteum and Nym- 
phea alba, and similar observations 
winter buds of Aldrovanda the leaves 
are reduced to a petiole, the lamina 
being absent. Now the lamina bears 
both the glands for which a peptic 
function is suggested in the text, and 
also the quadrifid processes which 
are believed to absorb the products 
of decay. Since the leaves of the 
winter buds have no lamina, and 
cannot therefore capture prey, we 
must believe that the glands on the 
petioles have merely general absorp- 
tive function, and are not specialised 
in relation to the products of the 
decaying victims of the plant. Ximi- 
were made by the late E. Ray Lan- 
kester (‘ Brit. Assoc, Report,’ 1850, 
published 1851, 2nd part of volume, 
p. 113). This being so we must sus- 
pend judgment as to the function of 
the quadrifid processes on the outer 
region of the lamina of the leaves of 
Aldrovanda. Charles Darwin appears 
to have been impressed with the im- 
portance of these facts, as I infer 
from a note pencilled in Prof. Mar- 
tin’s tranlation of ‘ Insectivorous 
Plants,’ where Duval-Jouve’s paper 
is discussed in a note by the trans- 
lator.—F, D.] 
