3io 
Maugham. — On the Mechanism of 
permit the passage of the waves with more effect than would be possible in 
any other type of cell, except laticiferous elements. 
The relations of the haustorial cells of Cits cut a to the sieve-tubes of 
the host plant, and especially the fact that almost complete, if not absolute, 
continuity of protoplasm is established between the sieve-tubes of the two 
plants, are interpreted as supporting the views advanced, as also are certain 
results obtained by the osazone method of locating sugars. 
It is suggested that in Angiosperms the * transition-cells * at the bundle- 
endings in leaves, and the companion-cells elsewhere, act as intermediaries in 
the exchange of sugar between the sieve-tubes and adjacent tissues. 
In the Gymnosperms the albuminous cells probably have a similar 
function. 
In a normal green plant sugar is synthesized inside the photosynthetic 
cells, and is not taken in as such from outside. 
The hypothesis does not require the passage of sugar outwards through 
the plasmatic membrane of one cell and inwards through the membrane of 
the next cell ; it thus falls into line with the known small permeability of 
protoplasm to sugars present outside, and with the power of protoplasm to 
retain sugars occurring inside the cells. 
The structural features of fibres, stone-cells, and the endosperm of 
Phoenix are interpreted as furnishing further evidence in support of the 
hypothesis. 
Differences in the adsorptive properties of the protoplasm in various 
parts of the plant, together with changes incidental to senescence, may also 
share in exerting a directive influence upon translocation. 
Reference is made to the application of the hypothesis to various plant 
groups, in particular the larger Brown Algae, the Mosses, and the 
Lycopodiales. 
Literature cited. 
Atkins, W. R. G. (1916) : Some Recent Researches in Plant Physiology. Whitaker. 
Bayliss, W. M. (1915) : General Physiology. Longmans. 
Beddard, A. P. (1905) : Recent Advances in Physiology and Biochemistry. (Edited by L. Hill.) 
Arnold. 
Benedict, H. M. (1915) : Senile Changes in Leaves of Vitis vulpina and certain other Plants. 
Cornell Univ. Agric. Expt. Sta., Mem. No. 7 . Abstract by Child in Bot. Gaz., vol. lxi, 
i 9 j 6, pp- 435-8. 
Blackman, F. F. (1912) : The Plasmatic Membrane and its Organization. New Phyt., vol. xi, 
p. 180 . 
Compton, R. H. (1909) : The Anatomy of Matonia sar??ientosa. New Phyt. 
Czapek, F. (1897 (1) ) : fiber die Leitungswege der organischen Baustoffe im Pflanzenkorper. 
Sitzber. d. k. Akad. d. Wiss. in Wien, vol. cvi, pp. 117 - 70 . 
(1897 (2)) : Zur Physiologie des Leptoms der Angiospermen. Berichte d. deutsch. 
bot. Gesellsch., pp. 124 - 31 . Cf. also Bot. Centralbl., vol. lxxii, pp. 74 - 5 . 
