173 
by the Roots of Living Plants. I. 
by Pantanelli ; consideration of the probable error in the present case, 
however, shows that no real significance can be attached to the differences. 
The average percentage absorption for each day is approximately equal in 
the case of peas, having regard to the magnitude of the probable error. In 
the case of maize there is a distinct rise in the percentage absorption of 
calcium on the second day. This indicates that equilibrium is reached 
quickly, probably during the first twenty-four hours that the plant is 
growing in the experimental solutions, with peas, but rather later with 
maize. 
The fall in absorption at the end of the experiment is probably due 
to the toxic effect resulting from the presence of an unbalanced solution 
external to the roots. 
It is hoped to extend these observations to other species and solutions 
and also to mixed solutions. 
This research was undertaken at the suggestion, and under the direction, 
of Professor Stiles, and was financed by a grant from the Department 
of Scientific and Industrial Research. 
Summary. 
1. Further evidence has been obtained in support of the unequal 
absorption of the ions of a salt by the roots of growing plants. 
2. The difference in the rate of absorption of the ions was greatly 
reduced in less concentrated solutions ; in very dilute solutions, which alone 
affect the plant under normal conditions, it was almost nil. 
3. No evidence in support of periodicity in absorption was obtained. 
4. Equilibrium in the intake of this single salt, by roots of living 
plants, is reached within the first twenty-four hours of exposure to the salt 
solution in the case of peas, and within the first forty-eight hours with 
maize. 
5. Potassium and magnesium diffuse out from the roots to replace the 
excess of calcium absorbed, which explains how it is that the hydrogen-ion 
concentration of the solutions remained approximately the same. 
Literature cited. 
1. Crone, G. v. d. : Ergebnisse von Untersuch. uber d. Wirkung der Phosphorsaure auf d. hohere 
Pflanze. Diss., Bonn, 1904. 
2. Hoagland, D. R. : The Relation of the Plant to the Reaction of the Nutrient Solution. Science, 
xlviii. 422-5, 1918. 
3. Johnson, H. V. : The Absorption of Ions by Living and Dead Roots. Amer. Jour. Bot., ii. 
250-4, 1915. 
4. Meurer, R. : Uber die regulatorische Aufnahme anorganischer Stoffe durch die Wurzeln von Beta 
vulgaris und Daucus Carota. Jahrb. wiss. Bot., xlvi.. 503-67, 1909. 
