add up figures for twenty-five minutes, and then to copy out passages for another twenty-five minutes. Another day they performed the same work, but it was differently divided; they had to add for fifty minutes and to copy for another fifty minutes. Now these last tests gave results infinitely superior to the first. And yet it is well known that, in spite of such results, constant interruption and change of work are commonly practised in schools, as part of a scientific plan for combating fatigue. One of the researches directly relating to schools is that of the ponogenic co-efficient of the various subjects of instruction, that is to say, of the degrees of fatigue induced by these. Wagner is of opinion _a priori_ that one hundred, the maximum co-efficient, must be assigned to mathematics; in this case, we should get the following ponogenic co-efficients in schools, for each subject: Mathematics 100 Latin 91 Greek 90 Gymnastics 90 History and Geography 85 French and German 82 Natural History 80 Drawing, Religion 77 We may note the arbitrary and surprising manner in which such results are established; nevertheless, in the name of "experimental science" it is possible to make such deductions as the following: "It would be interesting to enquire if the order of the ponogenic co-efficients varies with the age of the children, which would enable us to know on the one hand when the brain is best fitted for the study of any particular subject and when therefore it would be most judicious to make it predominate in the program; on the other hand, it would help us in the arrangement of the daily time-table; we should take, if possible, the most fatiguing subjects at the beginning of the day" (Claparede, _op. cit._). Another order of recent researches is that made into the toxines produced by fatigue; Weichardt succeeded in isolating these toxines, and in fabricating anti-toxines with which he experimented successfully on rats. The experiments were also repeated in a clinic. With regard to the appearance of the toxines, it was found that they were abundantly produced during the performance of "wearisome" work, whereas there were only traces of them to be found when the work was "interesting." Throughout this science so packed with researches which give as their result unsolved problems, we perceive that not one of the factors taken into consideration can alleviate fatigue; interruption and change of work merely aggravate it. The one means by which _surmenage_ (exhaustion due to overwork) can be eliminated is to make work pleasant and interesting, to give joy in work rather than pain.