98 
LADIES 7 FLOWER GARDENER. 
The alternate action of vitiation and purification is emphatically 
described as follows by Mr. Ellis, in the pamphlet before us :— 
u Under a bright sunshine, the two processes by which carbonic 
acid is alternately formed and decomposed go on simultaneously; 
and their necessary operation, in as far as regards the condition 
of the air, is that of counteracting each other. Hence, though 
both may be continually exercised in favorable circumstances, the 
effects of neither on the atmosphere can be ascertained by ordi 
nary means; and, consequently, though, in the experiments of 
De Saussure with common air, the production and decomposition 
of carbonic acid by plants in sunshine must have been continually 
going on, yet, in all the analysis which he made, the air was 
found unchanged, either in purity or volume ; in other words, the 
processes of formation and decomposition of this acid gas exactly 
counterbalanced each other. 
“ Of the two processes which have now been described (con¬ 
tinues our authority), each may be considered as in its nature and 
purpose quite distinct from the other ; hence their efforts may be 
readily distinguished; neither do they necessarily interfere, when 
actually working together. The first or deteriorating process, in 
which oxygen gas is consumed, goes on at all times and in all 
circumstances when vegetation is active. It requires always a 
suitable temperature in which to display itself; and when that 
temperature falls below a certain point, which is very variable in 
regard to different plants, the process is more or less completely 
suspended, again to be renewed when the temperature shall re¬ 
turn. This conversion of oxygen into carbonic acid is as neces¬ 
sary to the evolution of the seed as to the growth of the plant, 
and is all that is required for germination. But the plant requires 
something more ; for if light be excluded, vegetation proceeds 
imperfectly, and the plant does not then acquire its proper color 
and other active properties which it ought to have. The chid 
