n preserved in the rocks. See "Fossil Plants as Tests
of Climate," page 40, A.C. Seward, 1892.

Since the first part of this note was written, a paper has been read
(May 29th, 1902) by Dr. H.T. Brown and Mr. F. Escombe, before the Royal
Society on "The Influence of varying amounts of Carbon Dioxide in the
Air on the Photosynthetic Process of Leaves, and on the Mode of Growth
of Plants." The author's experiments included the cultivation of several
dicotyledonous plants in an atmosphere containing in one case 180 to 200
times the normal amount of CO2, and in another between three and four
times the normal amount. The general results were practically identical
in the two sets of experiments. "All the species of flowering plants,
which have been the subject of experiment, appear to be accurately
'tuned' to an atmospheric environment of three parts of CO2 per 10,000,
and the response which they make to slight increases in this amount
are in a direction altogether unfavourable to their growth and
reproduction." The assimilation of carbon increases with the increase in
the partial pressure of the CO2. But there seems to be a disturbance
in metabolism, and the plants fail to take advantage of the increased
supply of CO2. The authors say:--"All we are justified in concluding is,
that if such atmospheric variations have occurred since the advent
of flowering plants, they must have taken place so slowly as never
to outrun the possible adaptation of the plants to their changing
conditions."

Prof. Farmer and Mr. S.E. Chandler gave an account, at the same meeting
of the Royal Society, of their work "On the Influence of an Excess of
Carbon Dioxide in the Air on the Form and Internal Structure of Plants."
The results obtained were described as differing in a remarkable way
from those previously recorded by Teodoresco ("Rev. Gen. Botanique,"
II., 1899

It is hoped that Dr. Horace Brown and Mr. Escombe will extend their
experiments to Vascular Cryptogams, and thus obtain evidence bearing
more directly upon the question of an increased amount of CO2 in the
atmosphere of the Coal-period forests.) It is pretty bold. The rapid
development as far as we can judge of all the higher plants within
recent geological times is an abominable mystery. Certainly it would be
a great step if we could believe that the higher plants at first could
live only at a high level; but until it is experimentally [proved] that
Cycadeae, ferns, etc., can withsta