Pe SSN Straten eneon, 
Cuar. XIU] DIGESTION, 243 
infusion of raw meat, to see whether they absorbed the 
vapour, but their contents were not affected. 
Digestive Power of the Secretion.*—When a leaf closes over 
any object, it may be said to form itself into a temporary 
stomach; and if the object yields ever so little animal 
matter, this serves, to use Schiff’s expression, as a peptogene, t 
and the glands on the surface pour forth their acid secretion, 
which acts like the gastric juice of animals. As so many ex- 
periments were tried on the digestive power of Drosera, only 
a few were made with Dionæa, but they were amply sufficient 
to prove that it digests. This plant, moreover, is not so 
* Dr. W. M. Canby, of Wilmington, 
to whom I am much indebted for 
information regarding Dionza in its 
native home, has published in the 
‘Gardener’s Monthly,’ Philadelphia, 
August 1868, some interesting ob- 
servations. He ascertained that the 
secretion digests animal matter, such 
as the contents of insects, bits of 
meat, &c.; and that the secretion is 
reabsorbed. He was also well aware 
that the lobes remain closed for a 
much longer time when in contact 
with animal matter than when made 
to shut by a mere touch, or over 
objects not yielding soluble nutri- 
ment; and that in these latter cases 
the glands do not secrete. The Rey. 
Dr. Curtis first observed (¢ Boston 
Journal Nat. Hist.’ vol. i. p. 123) 
the secretion from the glands. I 
may here add that a gardener, Mr. 
Knight, is said (Kirby and Spence’s 
‘Introduction to Entomology,’ 1818, 
vol. i. p. 295) to have found that a 
plant of the Dionza, on the leaves of 
which “ he laid fine filaments of raw 
beef, was much more luxuriant in its 
growth than others not so treated.” 
[The earlier history of the subject 
is given in Sir Joseph Hooker’s “ Ad- 
dress to the Department of Botany 
and Zoology,” ‘British Association 
Report,’ 1874, p. 102, whence the 
following facts are taken. 
About 1768 Ellis, a well-known 
English naturalist, sent to Linnzus a 
drawing and specimens of Dionea 
with the following remarks (“ A Bo- 
tanical Description of the Ponza 
muscipula.... in a letter to Sir 
Charles Linnzeus,” p. 37) :— 
“The plant, of which I now enclose 
you an exact figure. . . . shows that 
Nature may have some views towards 
its nourishment, in forming the upper 
joint of its leaf like a machine to 
catch food.” 
Linnzus was unable to believe that 
the plant could profit by the captured 
insects ; he only saw in the phenomena 
“an extreme case of sensitiveness in 
the leaves which causes them to fold 
up where irritated, just as the sensi- 
tive plant does; and he consequently 
regarded the capture of the disturb- 
ing insect as something merely 
accidental and of no importance to 
the piant. . . . Linnzus’s authority 
overbore criticism if any was offered ; 
and his statement about the behaviour 
of the leaves was copied from book to 
book. ... Dr. [Erasmus] Darwin 
(1791) was contented to suppose that 
Dionæa surrounded itself with insect- 
traps to prevent depredations upon 
its flowers. Dr. Curtis, whose con- 
tribution to the subject has been 
already mentioned, describes the 
captured insects as enveloped in a 
fluid of a mucilaginous consistence 
which seems to act as a solvent, the 
insects being more or less consumed 
by it.”—F. D.] 
t [See footnote, p. 106.—F. D.] 
E2 
