26 ORGANIC BEHAVIOUR 
be blown by the wind, touch and stick to these knobs, there 
follows an exudation of acid liquid, but no marked and con- 
tinuous change occurs in the position of the tentacles. But 
should an insect alight on the leaf, or a small piece of meat be 
placed upon the tentacles, not only is there a discharge of acid 
juice, but a ferment is also produced, which has a digestive 
action on the nitrogenous matter. 
Slowly the tentacle curves inwards 
and downwards, as one’s finger 
may bend towards the palm of 
one’s hand; neighbouring ten- 
tacles also turn towards and 
incline on to the stimulating 
substance ; then others, further 
off, behave in a similar way, until 
all the tentacles, some’ two hun- 
dred in number, are inflected and 
converge upon the nitrogenous 
particle. Nay, more: ‘“ When 
two little bits of meat are placed 
simultaneously on the right and 
re eee me es left halves of the same Sun-dew 
Leaf (enlarged) with the ten. leaf, the two hundred tentacles 
tacles on one side inflected divide into two groups, and each 
over a bit of meat placed on : : : 
the disc. (From Darwin’s O2€ of the groups directs its aim 
“ Insectivorous Plants.”) to one of the bits of meat.” * 
The movements, though slow, are orderly, methodical, and 
effective, the secretions of many glands being brought to bear 
on just those substances which are capable of digestion and 
absorption by the plant. The seemingly concerted action is 
moreover due to an organic transmission of impulses from cell 
to cell—a transmission accompanied by visible changes in a 
purple substance contained within the cells. In the Sun-dew 
any tentacle may form the starting-point of the spreading 
wave of impulse. But in the Venus’s Fly-trap there are six 
* Kerner, “Natural History of Plants,” translated by F. W. Oliver 
> 
vol. i, p. 145. 
