44 
Franklin Kidd. 
TRANSLOCATION IN PLANT TISSUES. 
I N a recent paper entitled “ On the Mechanism of Translocation 
in Plant Tissues. An Hypothesis, with special reference to 
Sugar Conduction in Sieve-tubes,” 1 Mangham puts forward the 
view that the sugar originating inside the leaf cells travels through¬ 
out the plant “ without ever passing through the plasmatic 
membrane, or outer surface of the protoplasm in contact with 
the cell wall.” The path of translocation is the protoplasm, 
which by way of the connecting threads between individual cells 
and the protoplasmic lining of the sieve-tubes is continuous over the 
whole plant. 
The paper in question is stated to be the outcome of an attempt 
to form some mental picture in terms of physical chemistry, but 
certain of ,the physico-chemical statements upon which this hypo¬ 
thesis rests cannot be accepted as correct. 
The main features of the hypothesis can be best indicated by 
extracting from the summary appended to the paper. “It is 
suggested that pn vegetable protoplasm there are present con¬ 
stituents capable of absorbing sugars from solution. For any given 
concentration of sugar present in the liquid phase of the protoplasm 
and the cell sap continuous with it, there would be a definite 
concentration of sugar present at the absorbing surface. Any 
alteration of concentraction in either region would lead to a re¬ 
adjustment of concentration equilibrium, which would be propagated 
as a wave through the system . The rate of propagation of 
this wave would depend very much upon the degree of approximation 
of the adsorbing particles .... 
From the statements which have been italicised here it 
appears to the writer that Maugham’s mental picture is founded 
on fallacious physico-chemical concepts. Mangham considers that, 
if the absorbing particles were far apart, the “ rate of movement of 
sugar would be conditioned .... by the rate of diffusion; but, 
if the absorbing particles closely approximate, the rate of trans¬ 
ference would then approach “ that at which condensation on the 
surface of the absorbing phase would occur .... it would be 
extremely rapid.” Bayliss, Principles of General Physiology » 
pp. 56 and 61 is cited, but I have been unable to find under the 
reference any support for these statements. Bayliss rather 
appears to state clearly that while the actual process of attachment 
occurring when a substance reaches a surface at which it is 
1 Annals of Botany, 1917, 31, 293-311. 
