Apr. 7,1923 
Nutrition of Plants as an Electrical Phenomenon 
53 
disposal and as a matter of necessity have adapted themselves to the 
former. 
The plant seems to feed upon ions, and these ions are certainly mobile. 
If an ionic movement takes place between the root tips and the rest of 
the plant, it seems equally reasonable to assume the possibility that a 
similar movement might exist outside the plant and that the plant might 
draw its food from relatively long distances. 
The potassium concentration of young plants, sometimes having 
small root systems, often runs very high. The soil solution is relatively 
low in this element, and water movement and diffusion are neglible 
factors. The absorbing surface of the root is small, and, assuming 
that the root is obliged to come in contact with a soil grain before it 
can draw upon the potassium, it is rather difficult to account for the 
high potassium content of the plant. In the same way the writer has 
analyzed many samples of Australian saltbush that ran 8 per cent or 
more of sodium chlorid upon the basis of their dry weight. These 
plants had grown in a soil that was very low in sodium chlorid and in a 
semiarid climate where the soil moisture was very low for the greater 
part of the year. It seems hardly possible for a plant with growing 
habits like that of the saltbush to be able to absorb such quantities of 
salt as it does, if obliged to feed in the manner usually attributed to 
plants. It also seems hardly possible to conceive of this plant being 
forced to absorb sodium chlorid against its will, so to speak, because the 
salt is carried into the system by the transpiration stream or other 
agencies. A noticeable feature of this sodium-chlorid absorption is that 
the sodium (Na) is absorbed in much larger quantities than are necessary 
for combination with chlorin (Cl) in the formation of sodium chlorid 
(NaCl). The excess sodium exists in the plant in organic combina¬ 
tions and is broken down into carbonates upon ashing. Evidently 
there exists in the Australian saltbush a demand for sodium and chlorin, 
and the demand for sodium is greater than the demand for chlorin. 
This absorption of the sodium ions in excess of the chlorin, from a soil 
solution where the source of supply of these ions is sodium chlorid, which 
is in equilibrium, seems to eliminate the idea of “forceful feeding,” 
as applied to this plant. The high salt content of the plant, with such 
a low transpiration, would also indicate a wider field of absorption than 
is usually attributed to it. 
If a soil solution is in equilibrium and the salts are ionized and the 
ions are mobile, if an atom of the K, for example, bearing a plus charge 
is removed from solution by the root, the writer sees no reason why the 
position of this ion can not be filled by replacement and the charge 
carried along through the soil, as it is in a battery, to where the source 
of supply of potassium exists. If this be true, the plant will not be 
dependent upon the soil grains that touch the root tips, but it may 
actually feed at a distance, the distance probably following some well- 
known physical law. In practical agriculture we, involuntarily, think 
of the plant as having all the moist soil surface at its disposal. We 
also think that the water movement in the soil is neglible as far as nutri¬ 
tion is concerned, that the plant has to grow for its water, and that diffu¬ 
sion is also a neglible quantity. With plants that have a limited root 
system and with the absorbing zone of ffie root but a small part of the 
root itself, if we do not attribute to the plant the ability to feed at a 
distance, Ve will have to admit that only a small part of the soil is at the 
disposal of the plant. 
