284 PHILOSOPHICAL PERIODICALS. show little connexion with each other. In the reaction experiments, the authors emphasise the importance of observing the subject during the experiment. For instance, in the case of a subject who has to check a tendency to anticipation, the reaction tune may be lengthened if the signal comes just when he is thus restraining himself. The next set of experiments is concerned with respiration and circulation. In the circulation experiments, the authors bring out the interesting result that, unlike such exercises as running, which accelerate circulation, a brief and intense localised effort diminishes it quite appreciably. After a summary of various anatomical measurements, there follows a paper in which the authors indicate briefly the extent of the individual differences revealed in the various experiments. And the final paper of the first series deals with the correlations of the various tests taken together, two additional tests of a more intellectual character being included, one a memory test, the other that of the scholar's place in class. Two methods are employed in the study of the correlations of the tests. The first is that already employed in correlating the different tests within each set of experiments. It consists in classifying the subjects into four groups determined by some standard test (five such tests are taken), and then comparing the results of other tests in relation to this classification. The other method (methode du rang] is based on a com- parison of the places held by the same subject under different tests. In dealing with a group of subjects, it may be employed to determine either the mean of individual differences of place or the difference between the average places of the group under different tests. The method, however, is not here applied with reference to standard tests, but with reference to what the authors call a "classification globale " of the scholars. This classification is arrived at by adding together the places held by the individual scholar under all the physical tests (the more intellects' tests are excluded), so that the scholar whose sum of place-marks is lowest stands at the head. The scholars are then, by means of this classification, divided into four standard groups, and the method in both its forms is applied with reference to these. The interesting result is brought out that two of the respiration tests are decidedly the most representative for the complex of physical qualities investigated. The series of experiments carried out with the pupils in the training college was similar in character, and the parallelism gives an interest to the second series. Of the remaining papers, several of those written by the authors above named are more or less directly connected with the foregoing experi- ments. In two papers the authors examine possible sources of error ha certain instruments used, viz., the pressure instrument or dynamometer and Mosso's ergograph. In a third paper they describe a new and improve form of ergograph in which a spring is substituted for the weight used Mosso's instrument. In other papers they study some of the physiologies aspects of the experiments. For instance, in a paper on muscular con- traction, they find a rather striking difference in the sorts of fatigue produced by those experiments with the ergograph, which are directed testing ' force ' and ' vitesse ' respectively. In the former experiment (ir which a heavier weight is used), fatigue is expressed in an inability tc contract the finger which lifts the weight ; in the latter experiment (ir which a lighter weight is used), fatigue is expressed in precisely the opposite effect of a state of contraction. Two other papers by the same authors separately deal with certain aspects of the effect of intellectua' work on bodily functions. A final paper (by B. Bourdon) gives account of recent work upon the visual perception of depth. The second half of the volume is occupied by the Bibliography, which includes classi-
