472 



NATURE 



[April 15, 1922 



The " Index Kewensis." 



Index Kewensis Plantarum Phanero^amarum. Supple- 

 mentiim Quintum Nomina et Synonyma Omnium 

 Generum et Specierum ab Initio Anni MDCCCCXI 

 usque ad finem Anni MDCCCCXV Nonmdla Etiam 

 Antea Edita Complectens. Ductu et Consilio D. 

 Prain, confecerunt Herbarii Horti Regii Botanici 

 Kewensis Curatores. Pp. iii + 277. (Oxonii : e 

 Prelo Clarendoniano, 1921.) 765. net. 



THERE is probably no publication which is 

 awaited with such interest and impatience as 

 the issue from time to time of the supplements of 

 the " Index Kewensis.". Had it not been for the 

 interruption of the war, the list of genera and species 

 published, or the publication of which was ascertained, 

 in the five years 1911-15, would doubtless have been 

 available to botanists less than six years after the 

 second date. This delay was inevitable, but it may 

 be assumed that Supplement 6, comprising the years 

 1916-20, is well on the way and will be available 

 for workers before another five years have passed. 

 ' Some names published abroad during 1914 and 1915 

 were not noted in time for insertion in the present 

 supplement, but will be included in the next. 



A rough estimate shows that the present volume 

 indexes more than 33,000 species-names, and a perusal 

 of a few columns indicates the large number and 

 great variety of the books and periodicals which have 

 been searched during the compilation of the work, 

 which, so far as one can judge by inspection and trial, 

 maintains the high standard of accuracy and complete- 

 ness of the parts previously issued. It is a great help 

 to have a note of the date of publication of the book 

 or periodical cited ; the absence of this was a dis- 

 advantage in the earlier volumes. Similarly the 

 practice adopted in the previous supplement of not 

 attempting to distinguish between species and 

 synonyms, often a matter of personal opinion, has 

 again .been followed, and the work maintains its 

 character purely of an index. Attention is directed 

 in the preface to the fuller geographical citations as 

 compared with previous volumes ; thus in American 

 species the name of the State follows the indication 

 U.S.A. ; in Chinese, the name of the province, and 

 so on ; this additional information is a distinct gain. 



To the botanist a perusal of the columns is of special 

 interest as marking the progress of botanical explora- 

 tion generally ; thus the large number of genera and 

 species quoted as from China, especially the south- 

 western provinces and the Philippine Islands, suggests 

 the important work being carried on in those areas 

 by British and American collectors and investigators. 

 The progress of standard floristic works, such as the 

 NO. ?73 7, VOL. T09] 



" Flora of Tropical Africa," or series of monographs, 

 such as the " Pflanzenreich," is also recorded in these 

 cases under the genera of families specially concerned. 



The numerous entries under certain well-known 

 European genera, such as Hieracium, which fills ten 

 pages, and Rubus, which fills eight, recall the intensive 

 study of species and their segregation, which will doubt- 

 less continue to supply material for future supple- 

 ments. The many unwieldy trivial names, some- 

 times running into eight syllables, indicate the difficulty 

 of finding new names for species when these run into 

 the hundreds in individual genera. The occasional 

 appearance of names from periodicals antedating the 

 special period shows the great difficulty of sweeping 

 up all the literature. Thus a harvest of new names 

 has been supplied by Hegetschweiler's " Flora der 

 Schweiz " (1839), previously overlooked, and the 

 recognition of Philip Miller's " Abridged Dictionary 

 of Gardening " (edition of 1754), in which many genera 

 were carefully defined, necessitates the reference of 

 some well-known genera to Miller instead of to later 

 authorities. 



In the method of citation the recommendation of 

 the latest International Code of Rules is followed in 

 the use of the capital letter only for species-names 

 derived from a personal or a generic name. In the 

 manner of production, from the irreproachable Latin 

 preface onwards, the volume upholds the credit of 

 the Oxford University Press. 



Mental Measurement. 



(i) The Essentials of Mental Measurement. By Dr. W, 

 Brown and Prof. G. H. Thomson. (The Cambridge 

 Psychological Library.) Pp. x -I- 216. (Cambridge: 

 At the University Press, 1921.) 21s. net. 



(2) Hoiv to Measure. By Prof. G. M. Wilson and 

 Prof. K. J. Hoke. Pp. vii + 285. (New York: 

 The Macmillan Company ; London : Macmillan 

 and Co., Ltd., 1920.) 125. net. 



(i) "T^LEVEN years ago Dr. William Brown 

 1 > published as a thesis for his doctorate a 

 suggestive and original monograph on the use of the 

 theory of correlation in psychology. Later, by adding 

 one or two chapters of introduction and two or three 

 others on the so-called psychophysical methods, he 

 expanded this monograph into a compact manual 

 entitled " The Essentials of Mental Measurement." 

 Now, in turn, after another and a longer interval, the 

 manual itself has developed into a guinea royal-octavo 

 volume, extensively enlarged and exhaustively revised. 

 The larger additions consist for the most part of a 

 detailed series of mathematical arguments, examining 

 what is termed the " hierarchical theory," and bringing 



