plains to share in the rich feast than ascend to higher regions to avoid
it. Ball draws attention to the imperfection of our plant records as
regards the floras of mountain regions. It is, he thinks, conceivable that
there existed a vegetation on the Carboniferous mountains of which no
traces have been 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