136 



SCIENCE. 



[N. S. Vol. VIII. No. 187. 



other hypotheses, but positively by shaping 

 men's views regarding disease in a right direc- 

 tion ; but the great applications of this view 

 canae only when it was demonstrated that cer- 

 tain definitely recognizable microbes were the 

 cause of definitely recognizable diseases. It 

 was the precise, not mere general, knowledge 

 that most largely influenced practice. In the 

 same way regarding fatigue our most valuable 

 applications can be expected to appear only 

 when detailed and precise investigations have 

 reached a high degree of development. 



Not all fatigue is dangerous or abnormal, and 

 because children or scholars become tired it 

 does not follow that they are overworked. The 

 lowest functions, notably the heart beat, seem 

 to have an automatic or semi-automatic form 

 of recuperation ; so that, provided there is no 

 forcing of them to work at too high a speed, 

 recuperation keeps pace with exhaustion. The 

 highest functions, and, most of all, the brain en- 

 ergies demanded by civilized life, fatigue most 

 readily. At what point normal fatigue passes 

 into abnormal it is not easy to determine. The 

 best test is the capacity for recuperation. A 

 fatigue, however severe, whether physical or 

 mental, that is totally dissipated by a night's 

 rest can hardly be said to be abnormal. It is 

 only when the principal is being drawn upon 

 that the danger of exhaustion begins. Severe 

 effort, periods of strain and stress, are unavoid- 

 able in modern life. The capacity to undergo 

 them is a legitimate aim of education, but still 

 more important is the recognition of the danger 

 line and the strength to refrain. A most im- 

 portant phase of intellectual hygiene is that 

 suggested by the dangers of abnormal fatigue. 

 This is only slightly touched upon in the pres- 

 ent volume and still awaits a comprehensive as 

 well as practical treatment. 



' La fatigue intellectuelle ' must be welcomed 

 as a useful and ably prepared compendium ; it is 

 by no means a perfect book, possibly not even 

 as good a book as the imperfect material at 

 command made possible. There are some im- 

 portant omissions, such as the neglect of the 

 important work of Lombard and Hodge ; the 

 perspective is frequently unfortunate , many 

 pages being allotted to technical discussions 

 ■which more properly belonged to an appendix. 



and the main line of argument consequently 

 suffering in continuity ; and considerable ma- 

 terial is introduced, such as the long discus- 

 sion of the report on ' le surmenage intellec- 

 tuel ' of the French Academy of Medecine, 

 which is of a secondary interest and hardly ger- 

 mane to the rest of the work. None the less, 

 the volume is a noteworthy one, which no stu- 

 dent of psychology can afford to overlook. 



It is further noteworthy as the first volume 

 of a series on pedagogy and psychology. The 

 announcement of such a series indicates that in 

 France the problem of the relation between 

 these two disciplines has been seriously taken 

 up. The authors of the present volume are 

 most forcible in their expression of the view 

 that the pedagogy of the future must be founded 

 upon psychology, and that most of the old 

 pedagogy is ' verbiage.' The further progress 

 of this movement in France will be watched 

 with the greatest interest by those in America 

 who are laboring with the same problem. 



Joseph Jasteow. 



Syllabus der Pflanzenfamilien. Eine Uebersieht 

 iiber das gesammte Pflanzensystem mit Beriich- 

 sichtigung der Medicinal- und Nutzpflanzen. 

 Zweite, umgearbeitete Ausgabe. Von De. 

 Adolph Englee. Berlin, Gebriider Born- 

 traeger. 1898. 8vo. Pp. 214. 

 The near completion of Die natilrlichen 

 Pflanzenfamilien originated by Engler and Prantl 

 some ten years ago gives this Syllabus a pecu- 

 liar interest, as it attempts to place in compact 

 form the conclusions of the senior and only 

 surviving author of the Pflanzenfamilien with 

 reference to the relationships of the various 

 groups of plants. We can but feel that if the 

 cryptogamic projector had lived, the Uebersieht 

 would have been less one-sided, for on its crypto- 

 gamic side it shows patch-work instead of a 

 logical summarj' made from a broad perception 

 of relations and perspective. We shall criticize 

 the work mainly from the cryptogamic side, but, 

 as it represents the highest generalization of 

 the so-called Berlin school of botanists, it must 

 also be criticized in those points in which it de- 

 parts from their announced principles of tax- 

 onomy. For the arrangement of the sperma- 

 phytes it represents, without doubt, the work 



