NOTES. 
STATIC DIFFUSION OF GASES AND LIQUIDS IN 
RELATION TO THE ASSIMILATION OF CARBON AND 
TRANSLOCATION IN PLANTS \ By Horace T. Brown, F.R.S., 
LL.D., and F. Escombe, B.Sc., F.L.S.-—This paper is intended to 
be the first of a series descriptive of the work carried out by the 
authors in the Jodrell laboratory on the fixation of carbon by green 
plants, and deals mainly with the purely physical processes by which 
atmospheric carbon dioxide gains access to the active centres of 
assimilation. 
The new evidence which F. F. Blackman brought forward in 1895 
in favour of the gaseous exchanges of leaves taking place exclusively 
through the stomatic openings, presents at first sight certain difficul¬ 
ties of a physical nature, which have led to an examination of the 
whole question of the free diffusion of carbon dioxide at very low 
tension, and under a set of conditions very different from those under 
which the previous determinations of the coefficient of diffusion 
of carbon dioxide and air have been made by Loschmidt and others, 
where the gases were initially of equal tension, and the ratios of 
mixture departed widely from those of ordinary atmospheric air. The 
inquiry has led to the discovery of some new facts connected with 
the static diffusion of gases and liquids, which are of considerable 
interest, not only from the physical point of view, but from the 
explanations they suggest of certain natural processes which are 
primarily dependent on diffusivity. 
The method employed in the first instance for the determination 
of the diffusivity of atmospheric carbon dioxide was one of static 
diffusion down a column of air of a definite length, towards an 
absorptive -surface at the bottom of the column. When a static con- 
1 Abstract, from the Proceedings of the Royal Society, Vol. lxvi. 
[ Annals of Botany, Vol. XIV. No. LV. September, igoo.] 
