SCIENTIFIC SUMMARY. 
451 
■composition of these gases changes with the epochs of vegetation. — 3. During 
the period of inactivity, carbonic acid is in very small proportion, and is 
scarcely appreciable. Oxygen is present to the same extent as in atmospheric 
air. During the phase of activity the contrary 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 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 mul- 
berry and the 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 vessels increases, the easier and more 
complete are the injections. The injections are fuller in the roots than 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. Microscopic 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 
mercury in the areolae, as if in so many little pouches formed by thin 
portions of the wall ; the same observations have been made in regard to the 
reticulated vessels. 
Aphyllostachys. — Professor H. It. Goeppert’s fine memoir on this singular 
fossil plant, has been translated in the Journal of Botany for August. The 
author makes it the text of a sermon on Darwinism. In the course of his 
remarks he urges that no arguments in favour of the theory of Natural 
Selection are to be found in the order in which plants present themselves 
as regards their geological succession ; for it is known that the highest and 
lowest algge existed at the same period. Herr Goeppert’s arguments 
are not, however, quite conclusive : how, indeed, could they be so in the 
brief space he allots for the discussion of a question which hangs on so 
large a mass of botanical evidence P Plis observations on the character 
of Aphyllostachys are much more important than his theoretical abstrac- 
tions. He describes the specimen very minutely, and the plate which 
accompanies the paper gives one a clear notion of the character of the 
plant ; still he feels unable to decide on its affinities. He cannot find an 
analogous form in either recent or extinct florae, and he now, after fifteen 
years, is compelled to lay the matter before other botanists, in order that 
they may settle it. 
Botany at the British Museum. — The Annual Report shows that the officials 
in the Botanical Department have certainly not been idle during the past 
twelve months. The addition of specimens to the Museum amounts to 
several thousands ; and of microscopic slides of Diatomacece no less than 
5,000 have been purchased. In fact, the whole of the valuable collection of 
the late Dr. Greville and the late Dr. Gregory are now to be seen in the 
British Museum. 
A new South African Senecio has been discovered by Mr. M'Owan, of 
YOL. YI. — NO. XXY. K K 
