202 



M. M. McCooL 



solution, and in soil cultures. The concentrations in which no further 

 elongation of seedlings takes place, those in which slight growth occurs, 

 and those that result in no injury to seedlings, have been determined. As 

 a rule, Canada field pea seedlings were employed as indicators, although 

 in some instances wheat seedlings also were used. 



The methods of experiment and manipulation were the same as those 

 described in Part I. 



Toxicity of calcium 



Each of the other elements studied is far more toxic than calcium. In 

 fact, calcium ions do not prohibit groTsi:h of pea and wheat seedlings at 

 concentrations much below those that result in plasmolysis, although at 

 the higher concentrations some injury ensues. The results that were 

 obtained from the exjoeriments are summarized in the tables immediately 

 following : 



TABLE 1. Experiment with Canada Field Pea. 



Ten Plants 



Duration, Ten Days. Data for 



Composition of solution 



Pea 



Increase 



in length 



of tops 



Increase 

 in length 

 of roots 



Wheat 



Increase 



in length 



of tops 



Increase 

 in length 

 of roots 



Distilled water as the solvent 



N/2CaCl2 



N/3CaCl2 



N/SCaCU 



N/lOCaClo 



Distilled water 



Full nutrient solution as the solvent 



N/2 CaCl2 



N/4CaCl2 



N/5CaCl2 



N/lOCaCh 



Nutrient solution 



Soil cultures* 



N/1 CaCh 



N/2CaCl2 



N/4CaCl2 



N/5CaCl2 



Water 



None 

 Slight 

 SHght 

 Good 

 Good 



None 

 Slight 

 SUght 

 Good 

 Good 



None 

 None 

 Slight 

 Good 

 Good 



None 

 None 

 Slight 

 Good 

 Good 



None 

 SHght 

 Shght 

 Good 

 Good 



None 

 Slight 

 SUght 

 Good 

 Good 



None 

 Slight 

 Slight 

 Good 

 Good 



None 

 SHght 

 SHght 

 Good 

 Good 



None 



None 



2.0 cm. 



4.0 cm. 



5.1 cm. 



None 

 None 



2.5 cm. 



5. 1 cm. 



5. 1 cm. 



None 



None 



5. 1 cm. 



10.2 cm. 



None 

 None 



2 . 5 cm. 



6.3 cm. 



* Air-drj- soil, to which was added a quantity of the solution equal to thirty per cent of its dry weight. 

 •The soil employed was a sandy loam containing 3.5 per cent volatile matter. 



