On the Absorption of Ions by the Roots of Living 
Plants. 
I. The Absorption of the Ions of Calcium Chloride 
by Pea and Maize. 
BY 
GLADYS M. REDFERN, B.Sc. 
University College, Reading. 
Introduction. 
UMEROUS observations are on record which suggest an unequal 
1 >1 absorption of the ions of a single salt presented in solution to living 
plant cells. Thus, the long-recorded observation that water-culture solu- 
tions turn acid or alkaline after a time can be explained by supposing that 
the two ions of a neutral salt are absorbed to different extents, and that 
the excess of the more absorbed ion is accompanied in its entrance into the 
plant by an equivalent quantity of hydrogen or hydroxyl ion, according to 
whether the ion in question is negatively or positively charged, with the 
result that a corresponding quantity of hydroxyl or hydrogen ion is left in 
the external solution, which in consequence reacts alkaline or acid. Also 
Nathansohn (5, 6, 7), Meurer (4) and Ruhland (11), by immersing discs of 
plant tissue in various salt solutions of known concentration and analysing 
the solutions after a certain time, have obtained evidence of the unequal 
absorption of the two ions of the salts employed. The most extensive work 
on this problem is that of Pantanelli (8, 9, 10), who performed a long series 
of experiments with representatives of all the large groups of the Plant 
Kingdom. 
He came to the conclusion that the ions of the salts were absorbed in 
unequal proportions. As a rule the anions were absorbed more rapidly 
than the kations, but several exceptions were recorded, notably sulphates 
with Dicotyledons, and chlorides with Elodea , where kations were absorbed 
more rapidly than anions. In the case of the marine algae Ulva and 
Valonia more calcium than chloride was absorbed from a solution of 
calcium chloride. Pantanelli also obtained evidence of a marked periodicity 
in absorption ; at first the plants absorbed the salts rapidly, attaining 
(Annals of Botany, Vol. XXXVI. No. CXLII. April, 1922.] 
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