e joints and of
positions of the limbs, as well as of resistance encountered by any
movement. Muscular fatigue and soreness are sensed through the same
general system of sense organs. This sense is very important in the
control of movement, both reflex and voluntary movement. Without it, a
person lacks information of where a limb is to start with, and
naturally cannot know what movement to make; or, if a movement is in
process of being executed, he has no information as to how far the
movement has progressed and cannot tell when to stop it. Thus it is
less strange than it first appears to learn that "locomotor ataxia", a
disease which shows itself in poor control of movement, is primarily a
disease affecting not the motor nerves but the sensory nerves that
take care of the muscle sense.

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EXERCISES

1. Outline the chapter, rearranging the material somewhat, so as to
state, under each sense, (a) what sense cells, if any, are present
in the sense organ, (b) what accessory apparatus is present in the
sense organ, (c) what stimuli arouse the sense, (d) what are the
elementary responses of the sense, (e) peculiar blends occurring
within the sense or between this sense and another, (f) what can be
said regarding adaptation of the sense, and (g) what can be said
regarding after-images of the sense.

2. Classify the senses according as they respond to stimuli
(a) internal to the body, (b) directly affecting the surface of the
body, (c) coming from a distance.

3. What distinctive _uses_ are made of each sense?

4. Explore a small portion of the skin, as on the back of the hand,
for cold spots, and for pain spots.

5. Try to analyze the smooth sensation obtained by laying the
finger tip on a sheet of paper, and the rough sensation obtained by
laying the finger tip on the surface of a brush, and to describe
the difference in terms of the elementary skin sensations.

6. Is the pain sense a highly developed sense, to judge from its
sense organ? Is it highly specialized? highly sensitive? How does
its peculiarity in these respects fit it for its use?

7. Separation of taste and smell. Compare the taste of foods when
the nostrils are held closed with the taste of the same food when
the nostrils are opened.

8. Make a complete analysis of the sensations obtained from chocolate
ice cream in the mouth.

9. Peripheral vision. (a) Color sense. While your eyes are l