
On the Physiological Processes of Green Leaves. 29 
HuGHES MEDAL. 
The Hughes Medal is awarded to Sir Joseph Wilson Swan, F.R.S., for his 
invention of the incandescent electric lamp, and his other inventions and 
improvements in the practical applications of electricity. Not as directly 
included in the award, should be mentioned his inventions in dry-plate 
photography, which have so much increased our powers of experimental 
investigation. 
Researches on some of the Physiological Processes of Green Leaves, 
with special Reference to the Interchange of Energy between 
the Leaf and its Surroundings. 
By Horace T. Brown, LL.D., F.B.S8., and F. EScoMBE. 
Received January 9,—Read March 23, 1905. 
(This paper, and the three following ones, constituted the BAKERIAN LECTURE 
for 1905.) 
Part J.—DESCRIPTION OF APPARATUS AND METHODS. 
Introductory. 
In the following series of five papers we have endeavoured to bring 
together in a connected form the results of various researches carried out in 
the Jodrell Laboratory at the Royal Gardens, Kew, between the years 1898 
and 1901. The present account must be regarded as being supplemented by 
two previous publications; one on the “ Static Diffusion of Gases and Liquids 
in relation to the Assimilation of Carbon and Translocation in Plants” ;* and 
the other on “The Influence of varying Amounts of Carbon Dioxide in the 
Air on the Photosynthetic Process of Leaves.” t 
The main object of the research was, in the first place, to obtain a direct 
measure of the rate of photosynthesis in a leaf, when it is surrounded by an 
atmosphere containing an amount of carbon dioxide not far removed from the 
normal amount of 0:03 per cent.; and secondly to obtain more definite 
* «Phil. Trans.,’ B, vol. 193 (1900), p. 223. 
ft ‘Roy. Soc. Proc.,’ vol. 70 (1902), p. 397. 
