Permeability 
75 
Table XXXII 
Absorption of Ions by the Roots of Living Plants of Cucurbita Pepo. 
(Data from Pantanelli and Sella) 
Concentra¬ 
Duration of 
Absorption in 
mg. ions 
tion in gm. 
experiment 
c 
-\ 
Salt 
mols. per litre 
in days 
Kation 
Anion 
Potassium chloride 
0-03 
6 
23-38 
30-68 
Calcium chloride 
0-02 
14 
0-00 
51-39 
Potassium sulphate 
0-0188 
6 
n-6 
18-07 
Calcium sulphate 
0-0165 
19 
o-oo 
1-98 
Potassium acid phosphate 0-02 
10 
I ’ I 5 
49-04 
Calcium phosphate 
0-032 
12 
I-IO 
78-93 
These results exhibit very clearly the very great differences which 
may exist between the quantities of kation and anion absorbed by 
the roots of living plants in the same time. In all these experiments 
the anion was absorbed in excess of the kation, sometimes very 
greatly in excess. Calcium was absorbed either to a very slight 
extent, or not at all. 
This work was later extended by Pantanelli (1915 a, b, c ) to a 
number of other species, including freshwater plants ( Elodea cana¬ 
densis , Azolla caroliniana) , higher land plants [Allium Cepa, Phaseolus 
multiflorus, Cicer arietinum , Vida Faba, Lupinus albus), yeast of 
barbera and marine algae ( Gigartina acicularis , Cryptonemia Lomation, 
Phyllophora nervosa , Dictyota dichotoma , Ulva lactuca, Valonia 
utricularis). The experiments were carried out at temperatures 
between 15 0 and 20° C. A wider range of salts was also employed. 
Although some cases were observed in which equivalent quantities 
of the two ions of a salt were absorbed, in the vast majority of cases 
the absorption of the kation and anion was unequal. A number of 
Pantanelli’s results are collected in Table XXXIII. 
Pantanelli’s results, of which those shown here are only a small 
selection, show that unequal absorption of the ions of a salt is an 
almost universal phenomenon, at any rate in the concentrations 
used. Slight unequal absorption of the constituent ions of calcium 
chloride by beet, carrot and maize after the roots had been immersed 
in the solution (initially about 0-04 N) for periods varying from 8 
to 39 days, was also observed by Johnson (1915). Hoagland (1918) 
found that barley absorbed more nitrate than sodium from solutions 
of sodium nitrate, but that the two ions of potassium chloride were 
absorbed by this plant in equivalent proportions. 
