46 LOMBARD :
over long intervals the effects of hunger and of general fatigue disguised the results.
Unusual Mental Fatigue. — Twice in the course of the experiments the subject spent too many hours in measuring and tabulating results, and the work, together with the depressing weather which prevailed at the time, caused unusual mental fatigue. The weariness showed itself in a slight dizziness and an irritability which made him start at unexpected noises. During the experiments which were made at this time the peculiar sensation in the muscle, result- ing from the jerk produced by the blow, or from the sudden contraction of the muscle, a feeling which was ordinarily unnoticed became so acute and so disagreeable that toward the end of the examination it was hard for the subject to lie quietly. He had a strong desire to contract the muscles of the limb and foot of the side experimented upon, the feeling being comparable to that which one has in the muscles of the jaw after biting a piece of rubber hard. The more one thought of it the stronger became the temptation to move, until it seemed to the subject as if he were keeping quiet by a positive act of the will. This nervous desire to contract many muscles of the limb was suggestive of a central rather than a peripheral excitability, and at first thought was referred to the spinal cord. The idea suggested itself that the brain was weary and was therefore unable to exert the inhibiting influence which many suppose it to have over the centres of the cord, and that these centres being partially freed from control, were un- usually active. The subject found, however, that by directing his thoughts away from the experiments and to other subjects, by compelling himself to give
