VOLUME XLIll NUMBER 4 
BOTANICAL AZPITE 
APRIL 1907 
THE FORMATION OF INTUMESCENCES ON POTATO 
PLANTS: 
GERTRUDE E. DOUGLAS 
(WITH NINE FIGURES) 
During the winter of 1904-5, in some experiments to determine 
the relation of a soil fungus to potato plants, Professor ATKINSON 
planted some potatoes in pots, and after the young shoots were well 
started they were covered with bell jars to produce a moist atmos- 
phere, which would be more favorable for the growth of the fungus. 
In a few days intumescences were formed in great numbers, so that a 
large part of the plant was literally covered with them. This sug- 
gested that the potato plant would be an excellent subject with which 
to experiment to determine the cause of the formation of these intu- 
mescences, at least under certain conditions. The matter was then 
placed in my hands for this purpose. The subject was the more 
interesting because of the difference of opinion among plant physiolo- 
gists as to the influence of light stimulus in the formation of intu- 
mescences upon plants, as pointed out by VoN SCHRENK (Q) in 
his paper on “Intumescences formed as the result of chemical 
stimulation.” 
The methods used in the experiments for producing the intu- 
mescences were in general as follows: young plants were covered 
with bell jars and their roots supplied every day with an abundance 
of warm water, except in those experiments where the roots were 
kept cold. The absorption of water was thus very great, while the 
Saturated air under the bell jar greatly checked the transpiration. 
* Contribution No. 115 from the Department of Botany of Cornell University. 
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