vironment. 2. Enregistered reactions.
3. Simple reflex actions. 4. Compound reflex actions. 5. Tropisms. 6.
Enregistered rhythms. 7. Simple instincts. 8. Chain instincts. 9.
Instinctive activities influenced by intelligence. 10. Subconscious
cerebration at a high level (man).]

[Illustration: _Photo: J. J. Ward, F.E.S._

VENUS' FLY-TRAP

One of the most remarkable plants in the world, which captures its prey
by means of a trap formed from part of its leaf. It has been induced to
snap at and hold a bristle. If an insect lighting on the leaf touches
one of six very sensitive hairs, which pull the trigger of the movement,
the two halves of the leaf close rapidly and the fringing teeth on the
margin interlock, preventing the insect's escape. Then follows an
exudation of digestive juice.]

[Illustration: _Reproduced by permission from "The Wonders of Instinct"
by J. H. Fabre._

A SPIDER SUNNING HER EGGS

A kind of spider, called Lycosa, lying head downwards at the edge of her
nest, and holding her silken cocoon--the bag containing the eggs--up
towards the sun in her hindmost pair of legs. This extraordinary
proceeding is believed to assist in the hatching.]

Reflex Actions

Among simple multicellular animals, such as sea-anemones, we find the
beginnings of reflex actions, and a considerable part of the behaviour
of the lower animals is reflex. That is to say, there are laid down in
the animal in the course of its development certain pre-arrangements of
nerve-cells and muscle-cells which secure that a fit and proper answer
is given to a frequently recurrent stimulus. An earthworm half out of
its burrow becomes aware of the light tread of a thrush's foot, and
jerks itself back into its hole before anyone can say "reflex action."
What is it that happens?

Certain sensory nerve-cells in the earthworm's skin are stimulated by
vibrations in the earth; the message travels down a sensory nerve-fibre
from each of the stimulated cells and enters the nerve-cord. The sensory
fibres come into vital connection with branches of intermediary,
associative, or communicating cells, which are likewise connected with
motor nerve-cells. To these the message is thus shunted. From the motor
nerve-cells an impulse or command travels by motor nerve-fibres, one
from each cell, to the muscles, which contract. If this took as long to
happen as it takes to describe, even in outline, it would not be of much
use to the earthworm. But the moto