134 



M. M. McCooL 



Exiperimental work 



In the experiments from which the data presented in this section were 

 taken, the sulfates and chlorid of magnesium were used but only the chlorid 

 of calcium; that is, in one series CaClo and MgCl2 were employed, in another 

 CaCl2 and MgS04. The different salts of magnesium were used in order to 

 determine whether or not the acid radical is of importance in these studies. 



A study of Table 1 shows that the chlorids and sulfates of magnesium 

 are extremely toxic to pea seedlings. On the other hand, calcium chlorid, 

 even at relatively high concentrations, is not poisonous. The develop- 

 ment of the plants in the combined solutions is much greater than in pure 

 solutions of magnesium chlorid or sulfate. The growth of the plants in 

 the combined cultures does not, however, differ greatly from that of the 

 plants in the solution of the calcium salt alone; for example, in N/20 CaCl2 

 the total weight of the plants is 7.40 grams, in N/500 MgCl2 the weight is 

 practically nil, and in N/20 CaCl2+ N/500 MgCl2 the total weight is 

 9.95 grams. 



TABLE 1. Experiment with Canada Field Pea. Duration, Twenty-four Days. 



Data for Ten Plants 



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/20 CaCl2+N/20 MgCh. . . . 

 N/20 CaCL+N/100 MgCh. . . 

 N/20 CaCl2+ N/500 MgCL. . . 

 N/100 CaCl2+N/20 MgCh. . . 

 N/1.000 CaCl.+N/20 MgCh. 

 N/1,000 CaCl-2+N/lOO MgCl. 

 N/1,000 CaCl2+N/200 MgCl.. 



N/20 CaCl. 



N/100 CaCL 



N/300 MgClo. 



N/500 MgCh 



Distilled water 



N/20 CaCl2+N/20 MgSO^.. . . 

 N/20 CaClo+N/100 MgS04.. . 

 N/20 CaCl2+N/500 MgS04.. . 



N/20 CaCl. 



N/500 MgS04 



Distilled water 



5.70 

 6.65 

 6.10 

 5.85 

 1.70 

 8.60 

 6.60 

 5.00 

 5.70 



1 



1 



1.85 

 6.24 

 7.14 

 7.00 

 5.85 



9.70 

 10.90 

 9.95 

 8.85 

 3.10 

 12.80 

 9.60 

 7.40 

 8.45 



1.75 

 4.30 

 5.12 

 4.12 

 2.60 



1.84 



3.60 

 10.54 

 12.26 

 11.12 



8.45 



3.56 



12.0 

 14.5 

 13.0 

 12.0 



4.5 

 17.0 

 14.0 



8.5 

 11.5 



2.0 



6.0 



11.5 



15.0 



13.0 



9.0 



3.0 



6.5 



12.5 

 15.0 

 14.0 

 11.0 



5.0 

 10.0 

 10.0 

 12.0 



8.5 



6.5 

 12.0 

 14.0 

 13.5 

 12.5 



7.0 



* The average length of roots was determined hy measuring the main roots. The lateral roots were 

 not measured, as the weight is indicative of their development. These statements apply to all subse- 

 quent tables. 



fWeak growth, plants almost dead, not weighed. 



