The end in view will, I trust, be considered sufficient justification for the degree of personal reference which this occasions; since greater concreteness and reality attach to definite descriptions such as this.

The other laboratories, as those at Harvard and Columbia Universities, take up similar problems by similar methods.

I shall therefore go on to describe some recent work in the Princeton laboratory.
Of the problems taken up in the laboratory, certain ones may be selected for somewhat detailed explanation, since they are from widely different spheres and illustrate different methods of procedure.
I._Experiments on the Temperature Sense._--For a score of years it has been suspected that we have a distinct sense, with a nerve apparatus of its own, for the feeling of different temperatures on the skin.

Certain investigators found that this was probably true; it is proved by the fact that certain drugs alter the sensibility of the skin to hot and cold stimulations.
Another advance was made when it was found that sensations of either hot or cold may be had from regions which are insensible at the same time to the other sort of stimulation, cold or hot.

Certain minute points were discovered which report cold when touched with a cold point, but give no feeling from a hot object; while other points would respond only with a sensation from heat, never giving cold.