Toxicity of Various Cations 



213 



calcium chlorid are toxic in the order given. The results obtained by 

 Magowan are presented in the following table: 





.02 m 



.04 m 



.06 m 



.08 m 



.12 m 



.18 m 



MgCh 



64mm 

 446 

 462 

 552 



26mm 

 .321 

 333 

 386 



15mm 

 210 

 220 

 249 



10mm 

 134 

 144 

 168 



6mm 

 54 

 63 



84 



0mm 



NaCl 



24 



KCl 



31 



CaClz 



48 







Ammonium and manganese ions are far more deleterious than the above. 

 Seeds steeped in N/20 NH4CI show sHght injury, while those steeped in 

 N/50 MnCl2 are greatly injured. Whether these variations are due to 

 the difference in penetrability of the seed covering, the writer is unable 

 to judge from the data that he has obtained. 



The procedure in the second series of experiments was as follows: Two 

 hundred and fifty grams of air-dry soil (volatile matter 3.45 per cent) 

 was placed in glass tumblers. Ten uniform pea seeds were placed in 

 each tumbler, about one inch below the surface of the soil. One hundred 

 and twenty-five cubic centimeters of the solutions to be studied was 

 added to each tumbler of soil. The chlorids of ammonium, magnesium, 

 potassium, and calcium are injurious in the order given. These results 

 suggest that fertilizers should be judiciously applied to soils. 



TABLE 10. Germination of Seed in Soil as Affected by Salts 



Experiment with CaCU 



Composition of solution 



Length 



of tops 



(centimeters) 



Length 



of roots 



(centimeters) 



Notes on condition 

 of roots 



Control 



7.50 







0.60 



1.25 



7.50 



8.9 branched 







1.25 



3.75 



7.00 





N/1 CaCl2 





N/3 CaCU 



Dead. Few lateral roots 



N/5 CaCU 



Dead. Few lateral roots 



N/lOCaCU 



No injury 







