BOOKS AND CURRENT LITERATURE 203 



Inorganic Plant Poisons and Stimulants. — Under the editor- 

 ship of T. B. Wood, professor of agriculture in the University of Cam- 

 bridge, and of E. J. Russell, director of the Rothamsted Experimental 

 Station, the series of Cambridge Monographs is making its appearance. 

 Of these a thin volume of about one hundred pages by Miss Brenchley, 1 

 of the Rothamsted Station, presents the literature and our knowledge 

 of the influence of copper, zinc, arsenic, boron, and magnanese com- 

 pounds upon plants and the soils in which they are cultivated. 



Pointing out that different concentrations of the same compound 

 may act as stimulants to growth, or to other activities, or as repressants 

 or poisons, Miss Brenchley briefly discusses the bases of the difference 

 in behavior, without however leading to any definite conclusion upon 

 the foundation of present knowledge. In regard to this and the other 

 topics discussed, perhaps the most valuable contribution of the author 

 is the evidence that, at present we know very little about the subject. 

 At the same time it should be gratefully acknowledged that Miss Brench- 

 ley has saved the average plant physiologist much time and trouble 

 by bringing together the major part of the literature and briefly dis- 

 cussing the principal contributions. Doubtless the specialist on plant 

 poisons will miss the reference to certain papers, but to him such a book 

 is less useful. 



Two of the elements in this list of five are particularly interesting 

 to Americans because of their general use in sprays, fungicides and 

 insecticides, namely, copper and arsenic. The other three, zinc, boron, 

 and manganese have a much more limited interest, although Miss 

 Brenchley concludes that manganese may, under certain conditions, 

 be a valuable stimulant to growth and crop production. Copper and 

 arsenic appear not to act as true stimulants, the beneficial results of 

 their use depending entirely upon the toxic action of dilute solutions 

 of their compounds upon the parasites attacking their less readily 

 permeable hosts. The effect of copper on germination, for instance, 

 is nil or repressant; but the net result of its use may be advantageous, 

 because the copper compound may have killed fungus and bacterial 

 spores adherant to the seed coats. 



This book confirms the impression, increasingly strong in the re- 

 viewer's mind, that the greatest need of the biological sciences today — 

 of agriculture, horticulture, botany, zoology, and all their divisions — 

 is the application to the study of living organisms of those qualities 

 of mind, as well as the tools, which the chemist and physicist must 

 possess or cease to be chemist and physicist in any proper sense, namely 

 quantitative, not merely qualitative, accuracy. Biology has lagged 

 behind, is still too largely a descriptive science, is still mistaking what 

 is purely aviation for scientific hypothesis. — George J. Peirce. 



1 Brenchley, Winifred E., Inorganic plant poisons and stimulants. Pp. 110, 

 figs. 19. Cambridge University Press, 1914 ($1.25). 



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