108 BOTANICAL GAZETTE [FEBRUARY 
There are rather extensive areas where the salts of potassium, 
but more especially those of sodium, are present in the soil in amounts 
appreciable to plant life, but insufficient to cause distinct xerophily. 
Since these areas usually receive scanty rainfall, it is altogether 
probable that the action of those ions and salts which are here shown 
to retard the correlative transpiration would play an important part 
in plant growth. 
Concerning the action of pyrogallol and tannic acid, both of 
which greatly accelerated transpiration, but little remains to be said 
in this discussion. It may be added, however, that these, or closely 
related substances, are quite common in plants, and it is conceivable 
that their presence may influence transpiration independently of other 
factors. A similar view might be held of the action of oxalic and other 
organic acids which occur naturally as such in plants. 
VIRGINIA POLYTECHNIC INSTITUTE 
BLACKSBURG, VIRGINIA 
LITERATURE CITED 
I. BurGERSTEIN, A., Untersuchungen iiber die Beziehungen der Nihrstoffe 
zur Transpiration der Pflanzen. Sitzungsber. Akad. Wiss. Wien. Math. 
Nat. Cl. 83:191. 1876. | 
, Die Transpiration der Pflanzen. Jena. 1904. 
Garpner, F. D., Fertility of soils as affected by manures. Bull. 48, Bureau 
of Soils, U. S. Dept. of Agric. 1908. ; 
. Harter, L. L., The influence of a mixture of soluble salts, principally 
sodium chlorid, upon the leaf structure and transpiration of wheat, oats, 
and barley. Bull. 134, Bur. Pl. Ind., U. S. Dept. Agric. 1908. 
. Hartwett, B.L., WHEELER, H. J., anp Pemser, F. R., The effect of the 
addition of sodium to deficient amounts of potassium upon the growth of 
plants in both water and sand cultures. Ann. Rept. R. I. Agr. Exp. Sta. 
20:299. 1908. ; 
. Lawes, J. B., An experimental investigation into the amount of water given 
off by plants during their growth. Jour. Hort. Soc. London 5:38. 1859- 
. Lrvieston, B. E., Studies on the properties of an unproductive soil. Bull. 
28, Bureau of Soils, U. S. Dept. of Agric. 1905. 
8. , Asimple method for experiments with water cultures. Plant World 
9:13. 1906. 
, Further. studies on the properties of unproductive soils. Bull. 3° 
Bureau of Soils, U. S. Dept. Agric. 1907. 
10. Marrcker, M., Versuche iiber die Beeinflussung des Wasserverbrauchs der 
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