icking it with a pin at the thickest place, noting if pain is
felt. Inference?

3. Examine a finger nail. Is the free edge or the root the thickest? Trim
closely the thumb nail and the nail of the middle finger of one hand and
try to pick up a pin, or other minute object, from a smooth, hard surface.
The result indicates what use of the nails? Suggest other uses.

4. Examine with a microscope under a low power hairs from a variety of
animals, as the horse, dog, cat, etc., noting peculiarities of form and
surface.

*To illustrate Cooling Effects of Evaporation.*--1. Wet the back of the
hand and move it through the air to hasten evaporation. Observe that, as
the hand dries, a sensation of cold is felt. Repeat the experiment, using
ether, alcohol, or gasolene instead of the water, noting the differences
in results. These liquids evaporate faster than water.

2. Wet the bulb of a thermometer with alcohol or water. Move it through
the air to hasten evaporation. Note and account for the fall of the
mercury.

CHAPTER XVII - STRUCTURE OF THE NERVOUS SYSTEM

*Cooerdination and Adjustment.*--If we consider for a moment the movements
of the body, we cannot fail to note the cooeperation of organs, one with
another. In the simple act of whittling a stick one hand holds the stick
and the other the knife, while the movements of each hand are such as to
aid in the whittling process. Examples of cooeperation are also found in
the taking of food, in walking, and in the performance of different kinds
of work. Not only is cooeperation found among the external organs, but our
study of the vital processes has shown that the principle of cooeperation
is carried out by the internal organs as well. The fact that all the
activities of the body are directed toward a common purpose makes the
cooeperation of its parts a necessity. The term "cooerdination" is employed
to express this cooeperation, or working together, of the different parts
of the body.

A further study of the movements of the body shows that many of them have
particular reference to things outside of it. In going about one naturally
avoids obstructions, and if anything is in the way he walks around or
steps over it. Somewhat as a delicate instrument (the microscope for
example) is altered or adjusted, in order to adapt it to its work, the
parts of the body, and the body as a whole, have to be _adjusted_ to their
surroundings. This is seen in the attitude assumed in s