1918] Waynick: Antagonism and Cell Permeability L45 



The relationships of calcium to magnesium salts are reported in 

 the first seven tables. For a review of the more importanl literature 



bearing directly upon the relationships of the salts to these two ele- 

 ments reference is made to McCool, 26 who has considered these in 

 some detail, and to a recent critical survey of the lime-magnesia ratio 

 hypothesis by Lipman. 27 



As is evident from table 1, calcium chloride does not become toxic 

 until present in concentration of over .24 M. l T p to and including 

 this concentration the growth seems to be but little affected by the 

 increasing concentrations of the salt added. The percentage of cal- 

 cium in the plants shows no direct increase with increasing concen- 

 tration of calcium chloride in the solution. The lowest percentage of 

 calcium given occurs in a concentration of .20 M. calcium chloride. 



In table 2 there is a close parallelism between the growth of roots 

 and tops. Two low points on the dry weight graph are evident, the 

 first occurring at cultures 4 and 5 and the second from 7 to 11. At 

 these low points we have a high percentage of magnesium in both 

 roots and tops, but of calcium only in the second low point. Calcium 

 is low where growth is good in cultures 2 and 3. Hut the most inter- 

 esting feature is the decreased absorption of both elements at cul- 

 ture 6, where there is a distinct increase in dry weight. Iron was 

 not present in sufficient concentration to allow of titration until cul- 

 ture 11 is reached. It may be stated here that the iron determined is 

 limited to that in the seed as a maximum, for it was purposely ex- 

 cluded from the solutions except where its toxic or antagonistic action 

 was under observation. In many instances the tit rat ion of this residual 

 iron is of interest. 



Table 3 is a record of one of the most interesting and significant 

 series reported. The root growth was so limited in nearly every cul- 

 ture that no attempt was made to segregate roots from tops for sep- 

 arate determinations except where the total dry weighl was so greatly 

 increased as in cultures 6 and 11. In the first place we have double 

 maxima of growth, the first in culture 6 and the second in 11. The 

 total dry weight at culture 11 is twice that at (i. hut the dry weighl 

 in culture 6 amounts to a 35 per cent increase over that in culture 7. 

 A direct inverse relationship is shown between total growth and ab- 

 sorption at these two high points ; the maximum growth in culture 11 is 

 accompanied by the lowest absorption of calcium and magnesium. 

 The percentage of magnesium is low in culture li. hut thai of calcium 



-'■Cornell Univ. A»r. Kxj>. St:i. Mem. 2 i 1913), p. I2't 

 27 Plant world, vol. 19 (1916), p. 83. 



