with which the influence of practice and that of fatigue are lost. Fatigue passes away, comparatively very quickly, while the gain from practice, as already mentioned, is plainly demonstrable after weeks and even months. Thus it happens that with intervals of days or weeks each succeeding series of experiments begins with a quickness in calculation which is much greater than the highest achievement of the former experiment. The same takes place likewise after the short breathing pauses, as long as these pauses are sufficient to overcome in a measure the fatigue that has begun.
Since through the interpolation of pauses from work the otherwise inevitably sinking efficiency is kept at a nearly even height, the length of the periods of rest ought to be so adjusted that the injurious effects of fatigue should never acquire a predominance over the facility acquired by practice. If the experiment, however, is carried too far, the short pauses will no longer counterbalance the effect of fatigue, and the capacity to work will become null. For this reason the resting spells, if they are really to accomplish their purpose, should not only be much larger than they are now in our schools, but should succeed one another at shorter intervals and should be increased as the teaching is protracted.
The picture which we have to compose on the basis of the experiments under consideration is a gloomy one. While a quarter of an hour of simple work is enough to develop the first signs of fatigue in a twelve-year-old pupil, lessons of several hours' duration, interrupted only by a few short pauses, should soon lead to complete mental exhaustion. The demand on attention is much too long, the breathing spells are much too short, for healthy efficiency to be maintained only remotely.
The picture is, however, too darkly drawn. What I have sketched could take place only if the schools attained what they are striving for with all their means. Kind Nature has provided a safety valve for the salvation of our growing youth, the value of which can not be too highly estimated—inattention. Only by effort, and only for a short time, can we force a measurable concentration of the full force of attention upon the solution of the problem; care is therefore always taken in the school that the time of the session shall not be regarded wholly as a time of work. Burgerstein, indeed, thought that through the pauses he introduced the relation between effort and relaxation might be imitated in a regulated school hour. But these experiments seem to me to show to a certainty that our children would necessarily fall into mental disorder if they were really forced to work with full attention for forty minutes in each school hour. That, in fact, only a few are seriously injured by overwork in school is due to those interruptions to study and those incidents in teach-