128 



CHARLES B. LIPMAN 



The reviewer here purposely omits lengthy consideration of 

 the microorganisms which have been dealt with from similar 

 standpoints, giving primary consideration to the higher plants 

 themselves with regard to the Ume-magnesia ratio. He has done 

 so because of Loew's objection to one of his early pubhcations 

 which attested to the lack of antagonism between calcium and 

 magnesium for Bacillus siihtilis on the basis that the fungi and 

 bacteria are not affected by a lack of calcium since nucleo-pro- 

 teids and their importance in the chlorophyll bearing parts of 

 the higher plants probably have no analogy in the realm of the 

 protista, and also because effects on the microorganisms are not 

 necessarily translatable into terms of significance for the higher 

 plants. Nevertheless, it may be mentioned in passing that in 

 investigations carried out in the writer's laboratory, Kelley has 

 shown that no antagonism obtains between calcium and mag- 

 nesium carbonates so far as ammonifying and nitrifying flora of 

 certain soils are concerned. In further investigations the same 

 experimenter has pointed out that though all soils do not act 

 similarly to the California soils and that the relationships in ef- 

 fects between calcium and magnesium carbonates may often re- 

 verse themselves, that nevertheless, despite all of that, Uttle 

 reliable support could be found for the existence of a definite 

 lime-magnesia ratio for the soil flora. 



On the side of the higher plants, however, the writer has also 

 had occasion to carry out experiments on the lime-magnesia ratio 

 which remain as yet unpublished. These experiments were 

 carried out with beans and with citrus seedlings in the greenhouse, 

 in pots containing good, fertile soil. In the case of the beans, 

 no evidence through various mixtures of calcium and magnesium 

 carbonates could be obtained of the existence of a definite op- 

 timum ratio of lime to magnesia for those plants. Always, there 

 was present the marked toxicity of magnesium carbonate; like- 

 wise always a lack of evidence of the toxicity of calcium carbo- 

 nate, and no unexceptionable evidence indicating points at which 

 these were found in proper ratios for the crop in question. But 

 the experiments with beans lasting only two years should not be 

 perhaps over-emphasized for such purposes, and it is possible that 



