100 CHARLES B. LIPMAN 



The general conclusion reached by Gile is that an excess of Ume 

 or magnesia is toxic, not simply because of the ratio between 

 those two materials, but because of the improper balance be- 

 tween each of them, or both, and all the other salts present. 

 The problem therefore, as it appears to confront Gile, is not 

 merely the simple one of balancing the lime and magnesia be- 

 tween themselves, but also of balancing all other salts in a nu- 

 trient medium with the lime and magnesia. This interesting 

 deduction made by Gile is again very strikingly brought out by 

 the investigations of Tottingham,^^ which indicate that not so 

 much the ratio between the magnesium and calcium, but their 

 relationships to other materials in the solution and to the con- 

 centration of the whole solution, are factors which affect pro- 

 foundly the growth of plants. 



In a third paper'*^ published jointly by Gile with C. N, Ageton, 

 a discussion is given of soil experiments intended to test the 

 validity of the lime-magnesia ratio hypothesis. The results 

 were confhcting and the authors point out that the positive re- 

 sults as well as the negative results which they obtained, may 

 have been due to changes in the reaction of the soil. To quote 

 them further — ''From effects of salts on plants grown in water 

 cultures, we should not expect plants to be influenced by the 

 ratio of the bases under the conditions obtaining in any but 

 alkali soils." They point out — and this statement is well sup- 

 ported by numerous data from investigations on arid soils — that 

 the latter may be very fertile and with a very wide divergence in 

 ratios of lime to magnesia. They are therefore, at least to some 

 extent, justified in attributing to the lime-magnesia ratio in the 

 ordinary analysis of soils, decidedly minor significance, pointing 

 out at the same time that in alkali soils such a ratio may be 

 very important. 



The same authors in a further communication^^ detail experi- 

 ments with bush beans on soils containing varying quantities of 



" Physiol. Res., vol. 1, no. 4, p. 133-244, May, 1914. 



"2 Jour. Indus, and Eng. Chem., vol. 5, p. 33. Cited from E. S. R., vol. 28, 

 p. 812, 1913. 



" Jour. Indus, and Eng. Chem., vol. 5, p. 564. Cited from E. S. R., vol. 29, 

 p. 520, 1913. 



