ases, however, it is
referred even beyond this. Holding firmly in one hand a cane or a
pencil, touch an object therewith; the sensation is referred to the
extremity of the cane or pencil.

If, however, the cane or pencil be held loosely in one's hand, one
experiences two sensations: one corresponding to the object touched, and
the other due to the contact of the rod with the skin. The process of
mastication affords a good example of the reference of sensations to and
beyond the periphery of the body.

Experiment 167. Prepare a strong solution of sulphate of quinine
with the aid of a little sulphuric acid to dissolve it (_bitter_), a
five-per-cent solution of sugar (_sweet_), a ten-per-cent solution of
common salt (_saline_), and a one-per-cent solution of acetic acid
(_acid_). Wipe the tongue dry, and lay on its tip a crystal of sugar. It
is not tasted until it is dissolved.

Experiment 168. Apply a crystal of sugar to the tip, and another to
the back of the tongue. The sweet taste is more pronounced at the tip.

Experiment 169. Repeat the process with sulphate of quinine in
solution. It is scarcely tasted on the tip, but is tasted immediately on
the back part of the tongue. Test where salines and acids are tasted
most acutely.

Experiment 170. _To illustrate the muscular sense_. Take two equal
iron or lead weights; heat one and leave the other cold. The cold weight
will feel the heavier.

Experiment 171. Place a thin disk of _cold_ lead, the size of a
silver dollar, on the forehead of a person whose eyes are closed; remove
the disk, and on the same spot place two warm disks of equal size. The
person will judge the latter to be about the same weight, or lighter,
than the single cold disk.

Experiment 172. Compare two similar wooden disks, and let the
diameter of one be slightly greater than that of the other. Heat the
smaller one to over 120 degrees F., and it will be judged heavier than
the larger cold one.

Experiment 173. _To illustrate the influence of excitation of one
sense organ on the other sense organs_. Small colored patches the shape
and color of which are not distinctly visible may become so when a
tuning-fork is kept vibrating near the ears. In other individuals the
visual impressions are diminished by the same process.

On listening to the ticking of a watch, the ticking sounds feebler or
louder on looking at a source