. 
GURRENT LITERATURE 
BOOK REVIEWS 
Plant poisons and stimulants 
The first volume of the Cambridge Agricultural monographs" covers a 
very. much more restricted field than the title would lead one to expect, since 
it deals only with the effects, mainly upon the higher plants, of compounds 
of the five elements, copper, zinc, arsenic, boron, and manganese. Miss 
BRENCHLEY has previously published some of the results of work with these 
compounds which she has been carrying on since 1907 at the Rothamstead 
Experimental Station, * 3 these results being here brought together in con- 
nection with a résumé of certain portions of the related literature. 
An introductory chapter of six pages points out that the classification of 
the elements into the three groups, nutritive, toxic, or indifferent as respects 
their action upon plants, no longer holds, and expresses the belief that no such 
simple grouping is possible. The second chapter describes the water culture 
iz 
different methods, and asserts that “all crucial experiments have always been 
and must always be done in water cultures.’”’ Then follow five chapters, each 
devoted to discussion of the physiological effects of compounds of one of the 
five elements employed. The subdivisions of these chapters deal with such 
topics as the occurrence of the element in higher plants, its effects upon growth 
when present alone in water cultures, when present along with nutrient or non- 
nutrient salts or with pray substances, its effects upon growth in soils, its 
action upon algae and f and its effects upon germination of seeds and 
spores. A four-page asi entitled “Conclusions” and a bibliography of 
182 titles complete the w 
e general conclusions reached are that compounds of copper, arsenic, and 
in all crahabiiy those of zinc also, do not exert stimulatory effects in any con- 
centration when added to water cultures of higher plants, but are toxic at all 
concentrations having a discoverable effect. A stimulatory effect of each of 
! BRENCHLEY, WINIFRED M., Inorganic gi Ee and stimulants. 8vo. 
pp. Ito. figs. r9. Cambridge: University Press 
? BRENCHLEY, WINIFRED M., The influence “of copper sulphate and manganese 
sulphate upon the growth of biley: Ann. Botany 24:571-583. pl. 47. 1919. 
3————., On the action of certain compounds of zinc, arsenic, and boron on the 
O14 
> 
‘growth of plants. Ann. Botany 28:283-301. 191 
158 
