On the Mechanism of Translocation in Plant Tissues. 
An Hypothesis, with special reference to Sugar 
Conduction in Sieve-tubes. 
BY 
SYDNEY MANGHAM, M.A., 
Lecturer in Botany , Armstrong College , Newcastle-on- Tyne , in the University of Durham. 
With two Figures in the Text. 
HE transference of products of metabolism from their sources to their 
-L destinations, as in the case of sugars formed in leaves and stored or 
consumed in subterranean organs, may involve journeys over considerable 
distances, especially in the case of large trees. 
While it is highly improbable that any particular molecule, say, of 
dextrose ever passes immediately after formation rapidly over the whole 
path from leaf to root tip, yet movement for a certain distance obviously 
occurs. 
Evidence has accumulated 1 showing that, in the case of sugars, sieve- 
tubes play an important part in the normal process of translocation, and 
that Czapek’s 2 view that these elements provide the chief path for their 
rapid transference is the correct one. 
It is, in practice, scarcely possible to deal with the path taken by 
assimilates during their passage from the photosynthetic system without 
reference to the physico-chemical processes involved. 
The present paper is the outcome of attempts made to form some 
mental picture, in terms of physical chemistry, of what actually happens 
during certain phases of the process under consideration. 
It is almost unnecessary to say that any active flow of material through 
plant tissues must be associated intimately with the properties of living 
protoplasm, and so with its structure. 
Czapek 3 carried out a number of experiments in which he subjected 
petioles to killing by heat and by chloroform, to plasmolysis, and to 
1 Mangham (1910-11). An account of relevant anatomical and physiological data. 
2 Czapek (1897). 5 Czapek, 1. c., pp. 140 - 60 . 
Annals of Botany, Vol. XXXI. No. CXXII. April, 1917.] 
