304 



NATURE 



[November 4^ 1920 



on anthrax and on chicken cholera, the problems 

 of immunity, virulence, and attenuation, and the 

 crowning work on rabies. 



All this we read with the avidity of a child for 

 a twice-told tale, and the pen of Duclaux trans- 

 ports us back to the days when these discoveries 

 were revolutionising the realms of medicine and 

 surgery. Sir Rickman Godlee's "Life of Lord 

 Lister" has reminded us afresh of the influence 

 that Pasteur exercised on that great surgeon's 

 work, a debt which Lister acknowledged from the 

 inception of his own researches. Duclaux deals 

 more briefly with the later discoveries of Pasteur, 

 possibly because his own studies had lain more in 

 the direction of the researches on crystallography 

 and fermentations; this, however, is no blemish 

 upon the book, which must always remain a 

 classic in the history of science. 



The translation has been faithfully done ; at 

 times too faithfully. Thus, on p. 7, "The general 

 law, just now stated, that a science progresses 

 above all by changing its point of view, explains 

 the aid which it always derives from kindred 

 sciences," is too literal a rendering of "La loi 

 g^nerale 6noncde tout a I'heure, qu'une science 

 progresse surtout en changeant ses points de vue, 

 explique le secours qu'elle tire toujours des em- 

 prunts faits aux sciences ses voisines." 



The book is well printed, and illustrated by 

 several portraits of Pasteur at different ages and 

 by two portraits of Duclaux. A good index has 

 been prepared by the translators, who are also 

 responsible for an innovation in a scientific work 

 in respect of a "Who's Who" of persons men- 

 tioned in the book. Lister's knighthood is given, 

 but not his peerage, 



Duclaux 's work thus presented should find new- 

 readers both in Great Britain and America. 



A. S. M. 



Applied Plant Ecology. 

 Plant Indicators: The Relation of Plant Com- 

 munities to Process and Practice. By 

 Frederic E. Clements. (Publication No. 290.) 

 Pp. xvi-1-388 + 92 plates. (Washington: The 

 Carnegie Institution of Washington, 1920.) 

 Price 7 dollars. 



DR. CLEMENTS'S enthusiastic and prolific re- 

 searches in pure ecology are well known to 

 botanists. In his Wtest publication he endeavours 

 to apply his principles and methods to the prac- 

 tical problems of agriculture, stock-raising, and 

 forestry, with special reference to the Western 

 United States. According to his view, every 

 plant is an indicator of "conditions, processes, or 

 NO. 2662, VOL. 106] 



uses," because it is the product of the conditions 

 under which it grows. The individual, the species, 

 or the community may serve as an indicator, and 

 the choice of the unit to be employed in a given 

 case will depend partly upon the practical end in 

 view, and partly upon the ecological data avail- 

 able. To give a concrete instance : the species 

 Mertensia sibirica indicates the condition "deep 

 shade " in the montane forest of Colorado. In 

 using plant-communities as indicators Dr. 

 Clements relies mainly upon the dominant species, 

 so that in practice there appears to be no sharp 

 distinction between specific and community indi- 

 cators. His general classification of types of 

 grazing-land, however, is based upon plant-com- 

 munities, inasmuch as a uniform community of 

 grass, weed, or browse is held to indicate suit- 

 ability for cattle, sheep, or goats respectively, 

 while a prairie or a grass-scrub mictium [i.e. a 

 mixed community containing dominants both from 

 grass- and from scrub-associations] ' or savannah 

 denotes the advisability of mixed grazing by two 

 or three kinris of animals. .As an example of 

 "individual" indicator-criteria, it is stated that 

 ten "water-ecads " [i.e. habitat-forms correspond- 

 ing to ten different degrees of water-supply] of 

 Ranunculus sceleratus have been produced experi- 

 mentally ; plate 1 1 further shows photographs of 

 [natural] shade, alpine, and "normal" ecads of 

 Campanula rotutidifolia, Gentiana amarella, and 

 Androsace septentrionalis. 



The nature of plant-indicators, briefly explained 

 above, forms the principal topic of the first section 

 (chaps, i.— iii.), which also deals with the deter- 

 mination and application of indicators, and in- 

 cludes a short historical. r^sum^ of the indicator 

 concept. Chap. iv. gives a summary review of the 

 climax [i.e. climatic] formations of western 

 North America, and, judged by the account of 

 Chapparal-formations — which the reviewer is best 

 able to appreciate from personal knowledge of 

 analogous Mediterranean formations — is adequate 

 on the descriptive side ; some useful information 

 regarding rainfall and other environmental factors 

 is included, and the dominant species are recorded 

 for each formation. Altogether this chapter, 

 already outlined in a fprmer paper [F. E. 

 Clements, "Plant Succession," Carnegie Institu- 

 tion, No. 242, 1916], is a very useful addition tO' 

 the literature of plant geography. 



The most interesting portion of the book is the 

 last — -roughly one-third of the whole — in which 

 Dr. Clements discusses in detail the practical em- 

 ployment of indicators in the interests of farmers, 

 stock-raisers, and foresters. X striking feature 



1 Words in square brackets ar« the reviewer's. 



