150 



M. M. McCooL 



barium in soils and in plants has received special attention. According 

 to the results obtained by Failyer (1910), barium is a widely disseminated 

 element. It is present in most soils of the United States, the larger quan- 

 tities occurring in soils derived from masses carrying barite deposits. The 

 original source in all cases seems to be the feldspars of the igneous rocks, 

 the masses carrying barite being intermediate in formation. Barium may 

 be expected to be present in small amounts in soil water. Crawford (1908) 

 has noted its presence in various plants and has related its occurrence to 

 the loco disease. 



Toxicity of barium. — Although closely related to calcium the barium ion 

 is extremely toxic in pure solution, and, since it is widely distributed in soils 

 and is present in many kinds of plants, it is desirable to know definitely the 

 effects on the barium ion of the calcium ion with respect to plant growth. 



Relatively little work seems to have been recorded respecting the rela- 

 tions of barium. Through some experiments designed to determine the 

 extent to which this element may replace calcium in the growth of plants, 

 Suzuki (1910) found that, although barium is poisonous to plants at rela- 

 tively dilute concentrations, this poisonous action can be lessened con- 

 siderably by the presence of calcium salts. 



The data obtained by the writer as a result of experiments with Canada 

 field peas show clearly that barium is extremely poisonous to plants and 

 may be rendered innocuous by calcium. Moreover, when barium and 

 calcium ions are present in proper concentrations, the growth of pea seed- 

 lings may be slightly more extensive than in solutions of calcium alone. 



TABLE 17. 



Experiment with Canada Field Pea. 

 FOR Ten Plants 



Duration, Thirty Days. Data 



Composition of solution 



Green weight 

 of roots 

 (grams) 



Average length 



of tops 



(centimeters) 



Average length 



of roots 



(centimeters) 



N/100 CaCl2+N/2,000 BaCh. 

 N/100 CaCl2+N/4,000 BaCU. 

 N/100 CaCl2+N/8,000 BaCU. 

 N/100 CaCl2+N/10,000 BaCl 



N/1,000 BaCU 



N/4,000 Bad. 



N/8,000 BaCl2 



N/100 CaCh 



Distilled water 



2.30 

 2.51 

 2.40 

 2.50 

 

 Weight not 

 taken 

 2.40 

 2.65 

 1.43 



8.00 

 10.50 

 9.50 

 7.50 

 0.25 



4.00 

 6.00 

 8.50 

 7.00 



9.0 

 9.5 

 8.5 

 9.5 

 



Slight 

 8.0 

 9.5 

 6.0 



