342 Miscellaneous. 
dimerous. ‘The placente, accordingly, are only two. The groove 
on the stigma and the placentze are in line with the fertile stamens. 
Here, therefore, is a symmetrical and complete, regular but 
dimerous orchideous flower, the first verticil of stamens not antheri- 
ferous, the second antheriferous, the carpels alternate with these ; 
and here we have clear (and perhaps the first direct ) demonstration 
that the orchideous type of flower has two stamineal verticils, as 
Brown always insisted.—Silliman’s Journal, September 1866. 
Boussingault’s Researches on the Action of Foliage. 
A full abstract of the first part of these investigations, communi- 
cated to the French Academy of Sciences, is given in the ‘ Comptes 
Rendus,’ vol. lx. no. 18 (May 1865). Theodore Saussure had long 
ago ascertained that, while plants prosper and decompose carbonic 
acid gas in an atmosphere containing as much as one-twelfth or even 
one-eighth part of that gas, they promptly perish in unmixed car- 
bonic acid, apparently without decomposing any of it. Boussingault 
made his experiments in a better form, upon leaves only, avoiding all 
complication of the action of the roots or other parts of the plant. 
His results are :— 
1. That leaves exposed to sunshine in pure carbonic acid do not 
decompose this gas at all, or only with extreme slowness. 
2. But in a mixture with atmospheric air, they decompose carbonic 
acid rapidly. The oxygen of the atmospheric air, however, appears 
to play no part. 
3. Leaves decompose carbonic acid in sunshine as readily when 
this gas is mixed with nitrogen or with hydrogen. 
Although this decomposition of carbonic acid by green foliage must 
be a case of dissociation—a separation of carbon from oxygen—yet 
Boussingault recognizes an analogy here with an opposite pheno- 
menon, viz. with the slow combustion of phosphorus at the ordinary 
temperature. Phosphorus in pure oxygen emits no light, does not 
sensibly undergo combustion, but does so in a mixture of oxygen with 
atmospheric air, or with nitrogen, hydrogen, or carbonic acid. The 
analogy may even be carried further ; for while a stick of phospho- 
rus is not phosphorescent in pure oxygen at ordinary or increased 
pressure, it becomes so in rarified oxygen. And Boussingault equally 
ascertained that leaves which exerted no sensible action upon pure 
carbonic acid at ordinary pressure, decomposed it, with the liberation 
of oxygen gas, under diminished pressure. That is, rarefaction and 
mixture with an inert gas act alike in mechanically separating the 
atoms, whether of carbonic acid, as in the one case, or of oxygen, as 
in the other, so as to determine the action either of combination or 
of dissociation. 
In acontinuation of these investigations (Comptes Rendus, vol. Ixi., 
Sept. 25, 1865), Boussingault shows that carbonic oxide, whether 
pure or diluted, is not decomposable by foliage, and that this inert- 
ness of green foliage upon carbonic oxide goes to confirm the opinion 
maintained in his ‘ Economie Rurale,’ that leaves simultaneously de- 
