On the Relation between the Concentration of the 
Nutrient Solution and the Rate of Growth of Plants 
in Water Culture. 
BY 
WALTER STILES. 
Introduction. 
F ROM time to time during the last fifty years various writers have pub¬ 
lished the results of their observations on the effect of the concentration 
of the nutrient solution on the growth of plants. As a result of these 
researches from those of Birner and Lucanus 1 onwards, it has become clear 
that plants grow quite healthily in extremely dilute solutions, but it is not 
clear that the rate of growth of plants in such solutions is as great as 
that when higher concentrations are used. Recently Hall, Brenchley, and 
Underwood 2 have attempted to show that concentration of the nutrient 
solution influences very greatly the rate of growth of plants. The observations 
of these writers agree so ill with the conclusions arrived at by other workers, 
notably by Cameron, 3 that the publication of the results of some experi¬ 
ments on the effect of differences of concentration of the nutrient solution 
on growth seems justifiable. 
Methods. 
In conducting experiments involving the use of water cultures two 
main difficulties present themselves. In the first place, plants growing in 
water cultures under exactly the same conditions are very variable. As 
evidence of this it is only necessary to cite the results of some work by 
Brenchley, 4 where the dry weights of a number of plants growing in water 
culture under exactly similar conditions are given. 
1 Birner und Lucanus : Wasserculturversuche mit Hafer. Landw. Versuchsstat, vol. viii, 1866, 
pp. 128, 177. 
2 Hall, A. D., Brenchley, W. E., and Underwood, L. M. : The Soil Solution and the Mineral 
Constituents of the Soil. Phil. Trans. B. 204, 1913, pp. 179-200. 
3 Cameron, F. K.: The Soil Solution. Easton, Pa., 1911. 
4 Brenchley, W. E.: The Influence of Copper Sulphate and Manganese Sulphate upon the 
Growth of Barley. Annals of Botany, vol. xxiv, 1910, pp. 571-83. 
[Annals of Botany, Vol. XXIX. No. CXIII. January, 1915.] 
