These experiments all psychologists agree should be carried out without interrupting the usual routine of the school. They are to be regarded as an addition, an _extra_, and may be summed up as a means of scientific research, throwing light upon the regular psychical conditions of school studies. The principal results of such experiments have been: the multiplicity of mistakes made, and the difficulty of fixing attention; that is to say, they reveal the weariness, the degree of fatigue, in children. This gave the alarm! Old-fashioned pedagogy was concerned solely with what children ought to do. The idea that their nervous energies might be impaired was first called into being by the warning note of science. Researches into the causes of fatigue became more and more frequent, and coupled with such researches was the less immediate enquiry as to how fatigue could be "combated" or "alleviated." All the factors relating to the question were studied: age, sex, the degree of intelligence, the type of individual, the influence of the seasons, the influence of the various times of the day, of the various days of the week, of habit, intervals of relaxation, interest, variety of work, the position of the body, and, finally, position in reference to the cardinal points. * * * * * =Science is confronted by a mass of unsolved problems=.--The outcome of all these researches is a growing mass of unsolved problems. It has not been established whether males are more easily fatigued than females; whether the intelligent are more subject to fatigue than the unintelligent. With regard to the individual type, Tissie's conclusion seems to be the most noteworthy: "Each individual becomes fatigued or not according to his degree of will." In connection with the seasons it appears that fatigue increases from the first to the last day of school, but it is uncertain whether this is due to the influence of the seasons, or whether, as Schuyten affirms, the scholar's gradual exhaustion is due to the scholastic system. With regard to the time of day, "it is still a question whether the fatigue produced is less when the pupil works spontaneously, but this problem is a difficult one to solve." The days of the week when fatigue is least evident are Monday and Friday, but researches made in this connection are not definitive; as to habit, intervals of rest, interest: "in connection with these factors which are antagonistic to fatigue, it has been questioned whether they actually diminish fatigue, or merely cloak it, but no decision has been reached." A great variety of interesting researches have been made into the question of change of work with identical results--namely, that frequent change of work causes greater fatigue than continuous work of one kind, and that a sudden interruption is more fatiguing than persistence. The following experiment (quoted by Claparede) was made by Schultze: one day the girls were required to