420 BOTANICAL GAZETTE [May 
Salts and permeability to acids.—BRENNER* finds by the use of a deplas- 
molitic method on red cabbage that neutral salts modify the toxicity of acids. 
The following table shows the killing concentration of HCl, four hours expo- 
sure, following plasmolysis by the various salts: 
Plasmolytic Critical conc. of H ion conc. of 
_agent HCl in mols. critical sol. 
HOES Fo Wer CONE oii ov is ven es 1/1000 8.91 X10—4 
Blt 7% OOF CONE: Cok ieee. 1/800 1.29X10—3 
PAG EE OT.) Sa ep rs ene 1/600 1.38X10—3 | 
ME see 1/400 4.68X10—4 
Mg (NO;).+6 aq. 8.8 per cent...... 1/1000 1.09X10—3 
MgCl,+6 aq. 7.0 per cent .......... 3.16X10—3 
MgSO,-+-7 aq. 16.1 per cent......... 1/250 I.12X10—3 
Ca(NO,).+4 aq. 6.5 per cent....... 1/500 1.95 X10—3 
CaCl,+6 aq. 6.2 per cent......... 1/250 5.50X10—3 
Denies 2c ee eae 1/700 8.90X10—4 
Saccharose .1/700 8.71X10—4 
The author emphasizes the fact that salts antagonize the toxic action of 
strong mineral acid, H ion, just as they have long been known to do with other 
salts. The antagonistic action of salts toward H ions is due to the joint action 
of cations and anions of the salts. By change of color in the anthocyanin o 
the cells used, the author determined that acids enter uninjured cells very 
slowly, and that the effect of salts in reducing this entrance corresponds to 
their antitoxic effects. In cells that are killed by acids, NaCl, KCl, and 
KNO, favor the exosmose of anthocyanin, and salts of earth alkali delay it 
very much. Of the plasmolytic agents Mg salts proved very toxic. In 
Mg(NO,). no cells were alive after twenty-four hours, and in MgCl and 
MgSO, very few. The salts of alkalis were only slightly less toxic, except for 
KCl, which showed many cells alive after two days. In CaCl, the cells would 
remain alive and plasmolyzed for a much longer time, some of them for twenty- 
one days. The author emphasizes the toxic action of pure salts and the 
balanced or non-toxic nature of mixtures of salts WM. CROCKER. 
Soil moisture.—A new classification of soil moisture, based upon its 
behavior in freezing, appears to be founded upon scientific principles and to 
give a deeper insight into the actual condition of such water, its movement, 
and its relationship to plants. Bouyoucos™ has found that a portion of the 
soil moisture freezes readily near o°C., another portion only when a temper- 
ature of —4°C. is reached, and a third portion does not freeze at all. The first 
, W., Uber die Wirkung von Neutralsalzen auf die Saureresisteng, 
Sphere ae Lebensdauer der Protoplasten. Ber. Deutsch Bot. Gesells. 38: 
277-285. 1921. : 
%4 Bouyoucos, G., A new classification of soil moisture. Soil Science 11:33-47- 
1921. 
