260 ‘ Marcel de Serres on the Old World 
at present, contained few families; but such as existed in it had a 
greater number of species than the actual vegetable families. This 
ancient flora has left considerable masses of coal, and we can from 
that form an opinion of its vigour and beauty; it appears to have 
been tufted and luxuriant, like that of warm and humid islands. 
On the other hand, the arborescent flora of the coal period indicates 
a vegetation almost entirely terrestrial. It presents, in the last 
place, as an essential character, in every part of the globe where it 
has been met with, the most remarkable organic identity—a proof of 
the uniformity of temperature which then everywhere prevailed. 
Norte 5. We may form an idea of the quantity of carbonic acid 
which existed in the atmosphere of ancient times, by referring to 
the observations of Theodore de Saussure. This skilful natural 
philosopher has proved that from six to eight hundred parts of car~ 
bonic acid disseminated in the air rendered vegetation peculiarly 
vigorous, but that, when this proportion was considerably exceeded, 
the plants subjected to its influence rather quickly perished. If then 
the quantity of 6 or 8 per cent. existed in the atmosphere of ancient 
times, it would be a hundred times greater than the proportion now 
met with. Indeed, the proportion of carbonic acid in the atmo- 
sphere is now so inconsiderable, that it appears not to exceed from 
four to six ten thousand parts of its volume. Volcanic countries, and 
particularly the vicinity of Naples, are celebrated for their fertility 
just on account of the quantity of carbonic acid which is everywhere 
exhaled from the ground. The Grotte-du-chien is the locality 
where this exhalation is most abundant in Italy. 
Norte 6. We know, from M. Geeppert’s observations on the flora 
of amber, that the trees which produce this fossil resin occupied an 
immense area in northern countries, and probably extended to the 
polar regions of the globe. We now find nothing, in the same 
places, but mountains of ice. It is not necessary to suppose that the 
trees were of small dimensions; for they belonged chiefly to these 
families Abietineze and Cupressinee, which contain the largest 
vegetables of the coniferous order. The articles published in these” 
Journals in December 1858, on the discovery made by Captain 
MacClure of a district in the North Seas, all go to confirm these facts, 
affording us a new example of the vigorous vegetation which prevailed 
in geological times near the Poles. At a little distance from Bar- 
ing Land, (which is only at the southern extremity of that named 
Banks, the latter separated from Melville Island by an arm of the 
sea,) this intrepid navigator found, at about 500 feet above the level 
of the sea, a range of hills composed of a mass of wood in all states, 
from complete petrifaction to that of inflammable chips. He like- 
wise observed a large species of bivalve shell of the size of an oyster. 
These facts are remarkable, inasmuch as they indicate a vigorous 
vegetation in geological epochs in regions now covered with ice, and 
where the largest tree is the dwarf willow. We know that the 
