Recent experimental studies have given us reasons for believing that nerve cells in different individuals yield up their energy in response to stimulation with varying degrees of readiness.[30] Experience corroborates what Professor Bryan[31] has said: that some persons possess a leaky nervous system, wherefrom their vitalities flow away without issue in useful results. In such individuals activity will be likely to be in excess of that which the stimulus occasioning it should normally produce. Every one must have seen children, and adults as well, who when they hear a slight noise, for instance, which others do not mind, react with great vigor by jumping or screaming; or, when spoken to unexpectedly the face flushes, the lip quivers, and they become physically uncontrolled in a measure. In these instances the persons are unduly profligate in the expenditure of their means, and, in consequence, their capital is relatively soon exhausted.[32] [Footnote 30: Educational Review, _op. cit._] [Footnote 31: Addresses and Proceedings of the National Educational Association, 1897, p. 279.] [Footnote 32: _Cf._ Warner, The Study of Children, chapters viii and ix.] The writer last year conducted some experiments upon school children which yielded results that appear to confirm the view here set forth. Scripture's steadiness gauge was used in one test. This is designed to investigate stability of control by requiring a person to direct a light rod under guidance of the eye upon a point several feet distant, failure to accomplish this being announced by the ringing of an electric bell. The subject is usually required to make the trial fifteen times at a single test, and the number of successful attempts is taken to be in a way, although not always reliable, an index to his power of co-ordination. But more important than the success or failure in accomplishing the task is the index it affords of the nervous condition of the subject as revealed in the expressions of face and body. Tests were made in the morning, shortly following the opening of school, and again at half past eleven o'clock, or thereabouts, after the pupils had been working over their lessons for about two hours. One boy of eleven years, A. M., is a fair illustration of what might not inappropriately be called an exhaustive type, wherein nervous energy is readily depleted because of incessant waste. In the morning tests he was well controlled and accurate. A record of five tests made at half past eleven all show that after four or five attempts to place the rod upon the point the hand became very unsteady, the lips compressed, the region about the eyes showed unusual constraint, and the hand not being used was tightly clinched. Ten trials were usually sufficient to produce twitchings or _tics_ in the face and body, although nothing of this was ever noticed at other times. This boy invariably made hard work of the task, and all the physical