1903] BRIEFER ARTICLES 391 
(4, fg. 2). This was sufficient to prove that the tissues had not been 
injured, for in the time allowed they could scarcely have recovered 
from any injury that might have been received from the heat.? This 
was further affirmed by repetitions of the experiment, which gave only 
slightly varying results, and also by the fact that sometimes a small 
amount of starch was found in the whole area that had been enclosed 
by the cork, but never much in comparison with the amount found in 
other portions of the leaf. 
The slightly different results obtained are easily explained by the 
fact that the corks, each time, may not have been fastened equally tight, 
or the veins may not have been of the same prominence, thus affording 
admittance to varying amounts of air. 
In considering the facts brought out by these experiments, that 
when light is admitted to a leaf and at the same time the surface with 
the stomata is covered by a rather closely fitting object, and starch 
does not form, it seems evident that the cover hinders the free diffusion 
of CO,. The experiment, as usually given, therefore, is not reliable. 
Disks of paper or cork, if used at all, should be attached so loosely that 
they do not obstruct the free access of CO, to the stomata.— BERNICE 
L. Hauc, Detroit, Mich. 
°The fact that starch formed along some of the veins or along a fold in the 
leaf, or when the cork was not tightly appressed, also shows that the tissues were not 
injured 
