1868.] | Botany and Vegetable Physiology. 75 
Gases in Plants.—Messrs. Faivre and Dupré have experimented 
on this subject and submitted their results to the Edinburgh Bo- 
tanical Society. They examined more especially the mulberry and 
the vine, and have arrived at the following conclusions:—1. The 
presence of gases in the interior of the root, stem, and branches in 
the mulberry and vine is a normal and constant fact. 2. The com- 
position of these gases changes with the epochs of vegetation. 3. 
During the period of inactivity, carbonic acid is in very small pro- 
portion, and is scarcely appreciable. Oxygen is present to the same 
extent as in atmospheric air. During the phase of activity the con- 
trary takes place, and the changes are more marked in proportion 
as the vegetation is more energetic; with the progress of vegetation, 
the proportion of oxygen diminishes. 4. In the roots during the 
epoch of vegetation, the quantity of oxygen is not so great, while 
that of carbonic acid is greater than in the branches examined under 
the same circumstances. 5. In the branches, as well as in the roots, 
there is an inverse relation between the oxygen and the carbonic 
acid; by adding to the normal oxygen that disengaged under the 
form of carbonic acid, we obtain a number which is scarcely above 
the proportion of oxygen in the air. 6. In the mulberry and vine, 
injections do not penetrate the pith or the bark, whether in the 
branches or roots. The ligneous layers are alone permeable to 
mercury. The more the formation of the vessels increases, the 
easier and more complete are the injections. ‘The injections are 
fuller in the roots than in the branches; they are also more in the 
branches than in the young herbaceous shoots. In the old stems of 
. the mulberry, the central layers cease to be permeable. 7. Micro- 
scopic examination proves that the injection specially penetrates the 
pitted and reticulated vessels, and also the spiral vessels in the young 
herbaceous shoots. 8. The pitted vessels show distinctly the mer- 
cury in the areolz, as if in so many little pouches formed by thin 
portions of the wall; the same observations have been made in re- 
gard to the reticulated vessels. 
France.—Absorption by the Roots of Plants—It is still a vexed 
question as to how far the roots, of plants absorb certain elements 
of their food, such as carbonic acid. M. Corenwinder has applied 
himself to the solution of this problem, believing that very rash state- 
ments as to the functions of the roots have been lately made by M. 
Boussingault and others. He states it as his conviction that plants 
have not the power of absorbing carbonic acid from the soil by their 
roots, or that at least the quantity which permeates the tissues from 
this source represents but a very small proportion of the total amount 
of carbon their tissues contain. Boussingault stated that in the air 
contained in an ordinary soil he found no less than ten per cent. of 
carbonic acid. M. Corenwinder asks what is the source of this large 
quantity of gas, and replies that it atises from the mass of decom- 
