1903 | BRIEFER ARTICLES 465 
place of absorbed water. Tube and branch were then sealed into the 
cork with the beeswax mixture, and the leafy and the leafless branch thus 
arranged were placed out of doors for some hours in full sunshine, after 
being carefully weighed. Reweighing at the end of the period gave 
the loss of water. 
On April 5 the leaves had not attained their full size, but nearly so, 
and were in excellent condition for the experiment. A branch 4o™ 
long had twenty-three leaves, with a total area (reckoning one surface 
only) of 17.5%. The area of the branch with its four twigs, was 
about 51.89, 
In three hours of sunshine, at a temperature in the shade of 20 to 
22° C., the leafless branch lost 1.32" water and the leafy one 2.472. 
The probable loss of water through the leaves of the leafy branch was 
therefore 247 — L.g20r nis. Katioot 2s - aes = ie = 0.87, 
The ratio of the loss by unit area of the leaves to that by unit area of 
the stems would therefore have been about 0.87 X 3 or 2.61. Itshould 
be noted, however, that the upper epidermis of the leaves of Spartium 
contains a good many stomata and doubtless performs a considerable 
part of the work of transpiration, so that the value 2.61 is somewhat 
too large. 
A repetition of the experiment on April 13, when the leaves had 
practically attained their full size (except in the case of a few at the 
tips of the branches), gave a loss of 3.24% for the leafy branch and 
1.15%" for the leafless one. The branches were for three hours in full 
sunlight at a temperature of 22° C. during most of the experiment. 
The relative amount of transpiration performed by the leaves and 
the green cortex of this shrub is evidently not necessarily a measure 
of the relative amount of photosynthetic work. But it would seem 
probable that, since the leaves excrete a much larger amount of watery 
vapor in proportion to their area than the cortex does (and sometimes 
a larger total amount), they must also fix more of the carbon dioxid 
admitted to the tissues of this plant than the cortex does. 
Some indirect evidence points very strongly in the same direction. 
Most of the growth of the Spartium in the neighborhood of Naples 
takes place between February 1 and July 1. I have no detailed 
humerical statement to make on this head, since,the idea of taking 
measurements for the purpose did not occur to me until too late in the 
Season. But two years’ observation has made me sure of the fact above 
Stated. Leafy individuals examined June 1 show branches 50 long 
