198 MISSOURI BOTANICAL GARDEN. 
production seems to be too deep-seated in heredity to be 
easily overthrown by any artificial external stimulus. The 
observations of Fritsch (’07), Benecke (’08), Copeland (’09) 
and Danforth (’10), lend great weight to this idea, as do also 
the studies of Williams (’05) on the Dictyotaceee. However, 
Benecke and Fritsch concede that if we could fully imitate 
the conditions found in nature we might get the same results 
regardless of season. 
EXPERIMENTATION IN LABORATORY—SPECIAL. 
In order to test more fully what I had noticed, as to the 
water becoming alkaline by the growth of alge, I arranged 
several series of cultures with and without carbonates of 
various kinds. 
November 24, Test-tubes were filled with distilled water 
and boiled to drive out any COz that might be present; then 
they were stoppered and allowed to cool. When cool, small 
quantities of the following plants were put in: Hydrodiet- 
yon, Oedogonium, Elodea and Spirogyra. The tubes were 
stoppered as tightly as possible and placed near an east 
window. In another set of test-tubes with distilled water as 
in the others, instead of boiling, a little powdered calcium 
carbonate was used, which was intended to absorb all the free 
carbon-dioxide. These were supplied with plants from the 
same source as the others, stoppered in the same manner and 
placed alongside the others, near a window. 
December 24. At the end of a month the Oedogonium 
and Spirogyra in the tubes of boiled water were dead and 
black, attacked by moulds and beginning to putrefy. The 
Hydrodictyon, though still green and apparently alive, 
showed no oxygen bubbles or other sign of activity, like that 
of the check material. The Elodea, likewise, was green, but 
dormant. All the tubes containing lime carbonate were 
bright and active, as shown by an abundance of oxygen 
bubbles. Since all the tubes were tightly stoppered to exclude 
the air, the only source of COz for photosynthesis was that of 
the bicarbonates, which showed that the plants named could 
utilize the COz from this source. 
