78 THE BOTANICAL MAGAZINE. [Vol. xxxiv.No. 402. 



above (especially from 10.0 to 18.0). While the MgS0 4 : Ca(N0 3 ) 2 - 

 ratio value required to produce noticeable injury was found to be 

 influenced by the total concentration, it did not appear to be affected 

 by the amount of KH 2 P0 4 in the solution ; it seemed to be dependent 

 especially on the ratio of Mg to Ca. 



Since there has been considerable discussion in the literature, 1 * 

 regarding the nutritional relations of magnesium and calcium for 

 plants, and since Japanese writers have taken part in the work 

 hitherto accomplished on this problem, we' originally undertook to 

 make a special study of the magnesium injury described for wheat 

 by Tottingham and Shive. Our prospectus included a morphological 

 and histological study 2) of the injured plants, as well as experimenta- 

 tion on the nature of the environmental conditional complexes that 

 bring it about. After some preliminary work we decided to include 

 a thorough experimental study of the growth of wheat seedlings in 

 3-salt solutions made up from the five potential ions, Ca, Mg, N0 3 , 

 H 2 P0 4 , thus omitting K altogether. It seemed that such a study 

 might bring forth new information regarding the Mg-Ca relations of 

 these plants, and that the results might also throw light on the K 

 relation. Some of the results of the first complete series of these wheat 

 cultures without any potassium in the medium form the subject of the 

 present paper. 



Methods of Experimentation. 



" Marquis " spring wheat (of the same lot of 1918 seed as has 

 been used by the cooperators with the Special Committee of the U. S. 

 National Research Council ; see p. 76, footnote) was employed, and the 

 seedlings were first sprouted on a germination net similar to the one 

 used by Shive, and with Shive's solution R5C2 (0.1 atmosphere). 

 When they were about 3 cm. high they were placed in perforated, 

 paraffined corks of the form first used by Tottingham. Each cork 



1) For a resume of this literature and a discussion of the problem, see : Lipman, 

 Charles B. A critique of the hypothesis of the lime-magnesia ratio. Plant world : 

 19:83-105, 119-135. 1916. 



2) Mr. Moeita showed very great aptitude for this sort of combination of mor- 

 phological and physiological study ; his mind seemed to turn with equal readiness to 

 the structural-static considerations and to the chemical-physiological ones. Had he 

 lived and continued in scientific work he would have excelled in both these phases 

 of botany. Marked ability in these two lines is rarely encountered in the same 

 person. — B. E. L. 



