417] W. FE. 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 KNO, partly or wholly replaced by KCl, 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 KNO, by NaCl depressed growth more 
than when KCl 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 KCl'in a complete fertilizer ration, but greater in- 
