120 Dr. H. T. Brown and Mr. F. Escombe. [Jan. 9, 
Table I—Mean CO, Content in Volumes per 10,000 Volumes of Dry Air, 
for the Month of July in each Year. . 
No. of CO, in parts 
Year. determinations. per 10,000. 
1898 ff 2°83 
1899 9 2°88 
1900 4 . 2°86 
OOM i oll 
We here see that in this month of active plant growth there was in 1901 an 
increase of 10 per cent. in the amount of atmospheric carbon dioxide over 
that of the three previous years. Assuming all other conditions to have been 
the same, both climatic and meteorological, such an increase would certainly 
be reflected in a correspondingly increased assimilation of the plant. 
This example, and the results which are tabulated below, indicate that in 
the percentage variations of the atmospheric carbon dioxide we have factors 
which can no longer be neglected by meteorologists and agriculturists. 
Systematic daily observations on the variations of the atmospheric carbon 
dioxide at widely separated stations are much needed for the purpose of 
ascertaining how far these variations are uniform over large areas, and also to 
what extent these changes in the composition of the atmosphere are reflected 
in the growth of our crops when they take place during periods of active 
plant growth. | 
