417] W. E. Tottingham 219 



ing to from 100 to 300 per cent. This gain in root length 

 was correlated with somewhat smaller gains in dry weight. 

 With wheat and clover the production of dry weight of tops 

 was depressed by this treatment but the percentage of nitro- 

 gen contained in the dry tops was unaffected. It will be 

 noted that the interpretation of these effects is complicated 

 by the fact that sulphur was absent where chlorine was pres- 

 ent in the solution. 



Buckwheat was grown in Knop's solution modified by hav- 

 ing KN0 3 partly or wholly replaced by KC1, thus avoiding 

 the omission of sulphur. Such treatment led to a slightly 

 increased production of stem and root when the replacement 

 was only partial, but complete replacement depressed the root 

 length and the dry weight of roots and leaves, the amount of 

 water lost by transpiration being proportionately decreased. 

 Total replacement of KN0 3 by-Nad depressed growth more 

 than when KC1 was used and transpirational water loss was 

 more than proportionately decreased. Comparison with the 

 necessary control solutions indicated that this effect is to be 

 considered specific for the NaCl molecule, an observation 

 which adds to the accumulating evidence that molecules must 

 be taken into consideration, and not ions only, in dealing 

 with the relations between the plant and the solutes of a 

 nutrient solution. The conclusion of earlier investigators, 

 that chlorine must be added to the nutrient solution for the 

 complete development of buckwheat, finds no support in the 

 present work. 



The sand cultures of this study (also in the greenhouse) 

 were conducted on 20-kilogram portions of sand, in open 

 boxes with paraffined inner surfaces. The insoluble salts 

 were incorporated with the dry sand and the others were 

 added in successive portions of solution. The total applica- 

 tion of salts was about 0.25 per cent, of the dry weight of the 

 sand. With mangel-wurzel, an increase of from 40 to 120 

 per cent, in the dry weight of roots resulted from the applica- 

 tion of KC1 in a complete fertilizer ration, but greater in- 



