194 



M. M. McCooL 



tion lacking calcium, rarely grow to a height of more than two inches. 

 However, if calcium is present, even in relatively small amounts, growth 

 proceeds for about four weeks. The ash of pea seeds contains relatively 

 small amounts of calcium, but the magnesia content is high. This unbal- 

 anced condition probably accounts for the demands for calcium in the 

 above instances. Taking cognizance of these facts, N/1000 CaClo was 

 used as the solvent in making up cultures in order to determine whether, 

 imder such circumstances, antidotal relation may be recognized to exist 

 between potassium and manganese. The solutions used and the results 

 obtained appear in the following table: 



TABLE 12. Experiment Continued for Thirty Days. Data for Ten Plants 



Composition of solution 

 (X/1000 CaCU as the solvent) 



Green 

 weight 

 of tops 

 (grams) 



Green 

 weight 

 of roots 

 (grams) 



Average 

 length 

 of tops 

 (centi- 

 meters) 



Average 

 length 

 of roots 

 (centi- 

 meters) 



N/50KC1 



N/50 KCl+N/100 MnCU 



N/50 KCl+N/500 UnCh. . . . 

 N/50 KCl+X/ 1,000 MnCh. . . 

 N/500 KCl+N/ 1,000 MnCU. . 

 N/1,000 KCl+N/1,000 MnCl2 



N/1,000 MnCh 



N/1,000 CaClo 



3.75 

 0.45 

 4.10 

 5.10 

 3.35 

 3.16 

 2.45 

 5.01 



5.05 

 2.01 

 4.08 

 4.25 

 4.02 

 3.15 

 3.35 

 3.35 



9 

 6 

 8 

 10 

 10 

 12 

 10 

 10 



Fig. 15. — Antidotal relations between potassium and manganese; N/1000 CaCl^ as the solvent 



1. N/IOOO CaCb 



2. X/oO KCl 



3. N/oO KCH-N/lOO MnCb 



7. N/1000 MnCl2 



4. N/50 KCl +N/500 MnCh 



5. N/50 KCl-hN/1000 MnCh 



6. N/500 KCl+N/1000 MnCh 



