namely the food, and the stimulus given by the
note excites a reaction which simply allows the act of seizing the food
to take place, or on the other hand stops it. In the case of answering
the call of the master the stimulus has to excite attention, to produce
perception of the locality whence it comes, and to invoke a complicated
series of movements of response. He finds that destruction of the
posterior colliculi of the mid-brain, which have long been known to be
in some way connected with hearing, likewise destroys the response to
the call of the master, but did not destroy the trick taught to his dogs
of taking meat offered at the sound of a note of one particular pitch
but not at notes of other pitch given by the same instrument.

_Other Senses and Localization in the Cortex Cerebri._--Turning now to
the connexion between the function of the cortex and the senses other
than those of the great distance-receptors just dealt with, even less is
known. Disturbance and impairment of skin sensations are observable both
in experiments on the cerebrum of animals and in cases of cerebral
disease in man. But the localization in the cortex of regions specially
or mainly concerned with cutaneous sensation has not been made
sufficiently clear to warrant statement here. Still less is there
satisfactory knowledge regarding the existence of cortical areas
concerned with sensations originated in the alimentary canal. The least
equivocal of such evidence regards the sense of taste. There is some
slight evidence of a connexion between this sense and a region of the
hippocampal gyrus near to but behind that related to smell.

As to the sensations excited by the numerous receptors which lie not in
any of the surface membranes of the body but embedded in the masses of
the organs and between them, the _proprioceptors_, buried in muscles,
tendons and joints, there is little doubt that these sensations may be
disturbed or impaired by injury of the _cortex cerebri_. They may
probably also be excited by cortical stimulation. But evidence of
localization of their seat in, and their details of connexion with, the
cortex, is at present uncertain. Many authorities consider it probable
that sensations of touch and the sensations initiated by the
proprioceptors of muscles and joints (the organs of the so-called
muscular sense) are specially related to the post-central gyrus and
perhaps to the pre-central gyrus also. The clearest items on this poin