s, have observed strong reflex actions. These and
other similar cases indicate clearly that reflex action occurs
_independently_ of the mind--that the mind neither causes nor controls it.
If a further proof of this fact were needed, it is supplied by experiments
upon certain of the lower animals,(106) which live for a while after the
removal of the brain. These experiments show that the nervous impulses
that produce reflex action need only pass through the spinal cord and do
not reach the cerebrum, the organ of the mind.

*The Reflex Action Pathway.*--By study of the impulses that produce any
reflex action, a rather definite pathway may be made out, having the
following divisions:

1. _From the surface of the body to the central nervous system_ (usually
the spinal cord). This, the _afferent_ division, is made up of di-axonic
neurons, and these have (in the case of the spinal nerves) their
cell-bodies in the dorsal root ganglia (page 295). They are acted upon by
external stimuli, while their impulses in turn act on the neurons in the
spinal cord.

2. _Through the central system_ (spinal cord or base of brain). This, the
_intermediate_ division, may be composed of mon-axonic neurons, or it may
consist of branches from the afferent neurons. In the case of separate
neurons, these are acted upon by impulses from the afferent neurons, while
their impulses serve in turn as stimuli to other neurons within the cord
(Fig. 129).

3. _From the central nervous system to the muscles._ This, the _efferent_
division, is made up of mon-axonic neurons. Most of these have their
cell-bodies in the gray matter of the cord, while their fibers pass into
the spinal nerves by the ventral roots.(107) They may be stimulated by
impulses either from the intermediate neurons, or from branches of the
afferent neurons. Their impulses reach and stimulate the muscles.

*Reflex Action in Digestion.*--The flowing of the saliva, when food is
present in the mouth, is an example of reflex action. In this case,
however, the organ excited to activity is a gland instead of a muscle. The
food starts the impulses, and these, acting through the bulb, reach and
stimulate the salivary glands. In a similar manner food excites the glands
that empty their fluids into the stomach and intestines, and stimulates
the muscular coats of these organs to do their part in the digestive
process. To a considerable extent, neurons having their cell-bodies in the
sympathetic g