1897 | RELATION OF NUTRIENT SALTS TO TURGOR 415 
bearing solutions is sufficient to create a difference in the turgor 
of 0.85 per cent., while the difference actually observed was only 
0.7 percent. This was exceptional, but in general the variation in 
the sum of the alkali metals followed that in the turgor quite satis- 
factorily. Only in the roots of Phaseolus did this fail. In these the 
per cent. of KC]+NaCl was greater in the K cultures, but the 
greater proportion of the lighter salt makes the mixture really 
more concentrated in the Na plants. The excessive turgor of 
the stems of Zea in the K solution (4%) was too much to 
explain by the accumulation of potassium. Still their sap con- 
tained 3.5 times as much of KCI+NaCl as did that of the Na 
plants. The stems of both Phaseolus and Zea grown in Na cul- 
ture were strikingly weak in K+Na, much more effected in this 
respect than were the roots by the supplanting of the potassium, 
the plant appearing less able to make its preference felt in the 
organs in immediate contact with the substratum. 
To make this table perfect to the chemist’s eye a correction 
would have to be introduced for the degree of dissociation. It 
is said that the most completely dissociated of all salts are 
_ those of sodium. If this be true, the combined osmotic power 
_ varies a very little more widely than does the combined equiva- 
lence from the sum of the per cents. of Na and K present in any 
mixture. Assuming still, however, that K and Na are present 
as chlorides, the available data point in the opposite direction, 
for Kohlrausch’s” original determinations of electrical conduc- 
tivity and Landolt and Bérnstein’s compilation, based partly on 
‘Rewer figures from Kohlrausch, both represent the potassium 
chloride as the more highly dissociated. 
From the analysis of the sap we must conclude then that the 
. in uence of potassium on the turgor of the plant is direct. When 
. offered to the roots it is taken up and stored in the cell-sap, 
_ where it becomes an important part of the osmotically active 
it does not share with sodium. Well known as is the useless- 
, Ueber das Leitungsvermégen einiger electrolyte in aensserst verdunnter wass- 
niger Lésung. Wied. Ann. 26: 161 (p. 195). 
