86 CHARLES B. LIPMAN 



nutrition are discussed. These papers are either referred to 

 specifically in the bibliography herewith submitted or are cited 

 in certain of the publications mentioned therein. It is not neces- 

 sary to mention them now, more in detail, since they merely 

 iterate and reiterate the now accepted facts first pointed out by 

 Loew with regard to the essential relationship of calcium to the 

 nucleo-proteids and the specificity of its functions with regard 

 thereto, and with regard to the similar relationship of magne- 

 sium to the translocation of phosphorus in the plant. The de- 

 tails of these excellent investigations and explanations are too well 

 known to my colleagues to require repetition here. 



In 1901 Loew and May^ carried out a series of investigations 

 in support of the lime-magnesia ratio hypothesis of the former. 

 Water, sand, and soil cultures were employed and the plants 

 grown were cowpeas, privet, tobacco, barley, oats, wheat and 

 beans. The nitrate, sulphate, and carbonate of each calcium and 

 magnesium were tested. The authors found that magnesium is 

 poisonous to plants when it occurs in great excess over hme, the 

 plants showing under its influence symptoms of starvation. 

 The addition of an excess of calcium counteracts the noxious ef- 

 fects of magnesium and with a proper ratio of the two bases, the 

 abnormal nutrition of the plant is obviated. It was further 

 claimed by these authors that the best ratio of soluble lime to 

 soluble magnesia for the germination and growth of plants is 

 5: 4 on the basis of molecular weight, and 7:4 on the basis of 

 actual weight. They appear also to have found that the more 

 soluble magnesium compounds, like the nitrate and sulphate are 

 more toxic than the less soluble forms and that the more soluble 

 compounds of lime are more efficient as antagonistic agents to 

 the toxicity of magnesia than the less soluble forms. With these 

 results as a basis, Loew and May draw conclusions for use in 

 practical soil management and formulate directions for liming 

 soils. 



In further support of the foregoing investigations of Loew and 

 of Loew and May, investigations were carried out under the in- 



, = Bui. 1, Bur. PI. Ind. U. S. D. A., 1901. 



