144 



M. M. McCooL 



that the most favorable gro"v\i;h m the mixed solution occurs when the cal- 

 cium-sodium ratio is 1 : 20. In anj^ case the protective action of the calcium 

 is apparent, and it is important that so small a quantity of this substance 

 is here required. 



Aside from the discrepancy just cited, the writer's results with field 

 peas are fairly comparable with those already mentioned. The data 

 are presented in detail in tables 10 and 11. The sodium salt is strongly 

 deleterious. A much stronger solution of sodium chlorid is required to 

 prevent top growth than to prevent further elongation of roots. When 

 N/50 NaCl is employed, slight development of tops occurs but there is 

 no root extension. When seedlings are placed in N/100 NaCl, the de- 

 velopment of tops is appreciable and the elongation of roots is very slight. 



In a mixed solution N/5000 CaCla + N/50 NaCl, the injurious property 

 of the sodium is entirely counteracted. Thus calcium is a powerful anti- 

 dote for sodium that is present in an injurious concentration. The 

 same beneficial relation exists when the calcium ion is present in much 

 stronger concentration, for example, in N/50 NaCl + N/20 CaCb. The 

 growth of the seedlings is greater than in the pure solutions of calcium. 

 Moreover, the results do not indicate, in general, that the most favorable 

 ratio will involve a relatively small proportion of calcium. 



TABLE 10. Experiment with Canada Field Pea. 



Data for Ten Plants 



Duration 



, Twenty-four Days. 



Composition of solution 



Green 



weight 

 of tops 

 (grams) 



Green 

 weight 

 of roots 

 (grams) 



Total 



green 



weight 



(grams) 



Average 

 length 

 of tops 

 (centi- 

 meters) 



Average 

 length 



of roots 

 (centi- 

 meters) 



N/50 NaCl+N/20 CaCU 



N/50 NaCl+N/500 CaCU 



N/50 NaCl+N/1,000 CaCU. . . . 

 N/50 NaCl+N/2,000 CaCl.. . . . 

 N/50 NaCl+N/5,000 CaCU. . . . 

 N/100 NaCl+N/1,000 CaCU. . . 

 N/50 NaCl ' 



6.10 

 5.15 

 6.20 

 6.00 

 6.10 

 4.70 

 Small 

 Small 

 5.00 

 1.82 



4.00 

 3.80 

 3.40 

 3.45 

 3.25 

 2.50 

 

 Inap.* 

 2.90 

 1.75 



10.10 

 8.95 

 9.60 

 9.45 

 9.35 

 7.20 

 Small 

 Small 

 7.90 

 3.57 



14.0 



12.0 



15.0 



15.5 



15.0 



12.5 



3.0 



4.0 



9.0 



6.0 



14.0 

 14.0 

 11.0 

 10.5 

 10.0 



9.0 







N/100 NaCl 



Slight 



N/20 CaCh 



12.0 



Distilled water 



7.0 







^Inappreciable. 













