_ $12 J, LeConte on the Correlation of Forces. 
of evolution of CO, as we have already said, is opposed by 
light bat favored by darkness and heat. Light favors the forma- 
the direction of most abundant manure. It is easy to'see, noe 
why roots avoid the light; since light decomposes CO, 4 
therefore must be unfavorable to the formation of this substance. 
7th. It is a well known fact that the so-called respiration of 
_ plants consists of two distinct and apparently opposite aman 
Ast, the absorption of CO, by the leaves and also in solution by 
a * Bib, Un. Arch. des Sciences, new series, vol. 1, p. 5. 
