46 



SCIENCE. 



[N. S. Vol. XXII. No. 550. 



parts, the first of which deals with the scope, 

 historical development, present status and im- 

 portant applications of ecology. Under the 

 latter caption its connection with physiology 

 and pathology, experimental evolution, taxon- 

 omy, forestry physiography, soil physics, zoo- 

 geography and sociology is pointed out. The 

 second chapter is concerned with the habitat 

 and methods of its investigation. First, the 

 factors are determined and classified and then 

 an account is given of the various instruments, 

 including geotomes, psychrometers, psychro- 

 graphs, photometers, selagraphs, thermom- 

 eters, clinometers, trechometers, etc., which are 

 employed in the study of the habitat, together 

 with methods of charting statistics. By these 

 instruments and methods statistical analysis of 

 soil water content, humidity, light, tempera- 

 ture, precipitation, wind, soil structure and 

 chemistry, altitude, slope, exposure, etc., is 

 made possible. There is attention paid to the 

 details of choosing instruments, stations and 

 readings. The plotting of curves and deter- 

 mination of , graphic representations is ex- 

 plained. The third chapter has to do with the 

 plant, the stimuli which it receives, the nature 

 of its response, its adjustment and adaptation 

 especially to water and light as stimuli. Here 

 some experimental evolutional methods are set 

 forth having to do with the selection of species, 

 the determination of factors and the recording 

 of habitat cultures and control cultures. The 

 fourth chapter, which is the most extensive 

 and to which the other three are in a sense 

 preliminary, has for its general subject the 

 formation or vegetation unit consisting essen- 

 tially of plants in a habitat, the need for ex- 

 act investigation of which is set forth by the 

 author. Quadrats, transects, migration circles, 

 are described and their use explained. The 

 two important arts of cartography and photog- 

 raphy in their relation to ecologic inquiry are 

 given space, and methods of preparing and pre- 

 serving formation and succession herbaria are 

 indicated. The development and structure of 

 vegetation are taken up under the conception 

 that the formation is a complex organism 

 which possesses functions and structure and 

 passes through a cycle of development similar 

 to that of the plant. The functions of a for- 



mation are described as association, invasion 

 and succession, while its structure may com- 

 prise zones, layers, consoeies, societies, etc., 

 all of which may be referred to zonation or 

 alternation. Thus classified, the facts and 

 laws of migration, dissemination, barriers arid 

 indemism, polygenesis, etc., are given detailed 

 discussion. The final pages are devoted to ex- 

 perimental vegetation with description of cul- 

 ture methods for formational aggregates. 



Throughout the volume Professor Clements 

 makes use of his carefully devised nomen- 

 clatural system, the extent of which is very con- 

 siderable. A great many thousand new words 

 and nomenclatural combinations are proposed, 

 for the most part derivatives from the Greek. 

 This system has already been brought to the 

 attention of ecologists in papers in Engler's 

 ' Jahrblicher ' (1902) and elsewhere and has 

 attracted attention. A glossary of ten pages in 

 which the more fundamental new words are 

 gathered is a l;ielpful addition to the work. 

 An index is not provided, but the glossary to 

 some extent fills its place. 



Eighty-five illustrations, for the most part 

 half-tones, of vegetation, plants and apparatus 

 serve to lighten up the text. Most of these are 

 original views of Colorado vegetation prepared 

 by the author and give a very excellent idea of 

 the grouping of plants upon some of the moun- 

 tain habitats. 



Altogether, Clements's ' Research Methods in 

 Ecology ' is a notable contribution to the liter- 

 ature of ecology and the author is to be con- 

 gratulated upon its successful delivery to the 

 botanical world. Conway MacMillan. 



The Becquerel Rays and the Properties of 



Radium. By Hon. E. J. Strutt. London, 



Edward Arnold. 1904. 



One closes Mr. Strutt's book with a feeling 

 of rare satisfaction. The reader has had a 

 clear and concise presentation of the funda- 

 mental phenomena of the Becquerel rays, and 

 the phenomena centering around that astonish- 

 ing substance, radium. 



The book, which lays no claim to an ex- 

 haustive treatment of the subject, is primarily 

 written for those who wish to know something 

 about radioactivity and are interested in sci- 



