j 
: 
: 
Se i ha SS ace alee 
Botany and Zoology. 127 
in the one case, or of oxygen as in the other, so as to determine the ac- 
tion either of combination or of dissociation. 
n a continuation of these investigations (Comptes Rendus, vol. ]xi, 
Sept. 25, 1865), Boussingault shows that carbonic oxyd, whether pure 
or diluted, is not decomposable 2 foliage, and that this inertness 
n carbonic oxy 
expresses the relation under which “tom is —— with the elements of 
water in cellulose, starch, sugar, &c., i.e. in the important principles 
elaborated = the leaves the ronpteition of which i is represented by car- 
bon and water. e goes on to prove that a leaf which has been decom- 
_ posing carbone acid and water all day long is capable of doing the same 
— the next day, if not allowed to dry, but the losing of a certain 
than that of some of the lower animals (Zardigrades, Notipes, to) 
which bear wonderful desiccation. 
he third instalment of the investigation is given in Nos. 16 and 17 
of the same volume (Oct. 16 and 23, 1865). It appears that detached 
leaves, kept in shade for many days, with the cut end of the petiole in ~ 
water to prevent ee sa ve the power of decomposing carbonic 
acid whenever brought into sunshine. But for this they must be kept 
in an at mosphere ¢ containing a prea of oxygen ; sore this they soon 
pane transformed into alent acid, through an -atxioree which is 
presumed to go on continually, whether in light or darkness, and to an- 
swer to respiration. Of course a healthy and active leaf decomposes far 
pibton rich in carbonic acid, a square meter _ folia age 
dec sermon on the average over a liter of carbonic acid - r, while 
in darkness only roo of a liter of carbonic acid was prod per hour. 
acid in the abersen cae oxygen. But ie latter, though liaiels smalh 
in ateit seems to be necessary to the preservation of their vitality. 
In hydrogen, cnbertad hydrogen, or —— as well as in pure car- 
bonic acid, they soon lose their decompos ing power, and die from the 
impossibility of respiration, i. €., are asphyxiated. 
es confined in a limited portion of atmospheric or other air over 
not under these circumstances at all Jose the power of transforming oay- 
gen into carbonic acid; but that is what we boekd expect, for the ear- 
bonie acid so evolved (whether its evolution be called as or not) 
~ = e a product of decomposition of the leaf’s —— or substance. 
owe to Boussingault and his assistant Lewy the min- 
ing a composition of the air contained in a fertile soil, poe the fact that 
