44. NEW HOLLAND IX EUROPE. 
After tills review, showing what a considerable portion of the Austra- 
lian and Polynesian flora was already represented by characteristic 
types in the Eocene vegetation, there can no longer be any donbi tliat 
Europe dood in some kind of counection with that didant continent. 
All now required is to determine more exactly their mutual relationship. 
Wherever in the investigation of natural phenomena we perceive simi- 
lar or the same effects, we are justified by a recognized general law to 
ascribe them to simihir or the sime causes. A vegetation in Europe, 
bearing the same character as that of New Holland and the adjacent 
islands of the present day, compels us to admit that, at that geological 
period, a set of conditions prevailed in our continent similar to those 
under which the Australian Hora at present exists. It is not conceivable 
that the climate and soil should have been the same as now, when our 
forests were formed by Arauracias instead of Pines, and our underwood 
of ProteacefSy Santaler£, etc. instead of Rhamni, Privets, and Hazels. 
We know but too well what peculiar conditions of temperature, light, 
moisture, etc., certain plants and whole groups of plants require, and 
how closely we are tied to certain rules in our cultivation of foreign 
plants. True, Araucarias^ Proteacere^ and Epacridefje grow, at pre- 
sent, exceedingly well in Europe, but only when protected by glass, 
in a certain artificial temperature and light, and a w^ell-prepared 
soil, — all calculated to approximate the exceptional conditions under 
which these plants are grown to those of their native conntiy.* We 
m'ay therefore conclude with good reason that the conditions which at 
present are produced artificially in order to grow these plants existed in 
the whole of Europe; in short, that at the Eocene period Europe must 
have had a climate like that of New Holland at the present day, I shall 
not enter into the details of these climatic conditions, the prevailing 
temperature, change of the seasons, the state of the atmosphere, the 
prevailing winds, and all the other causes which at present so strongly 
influence the vegetation of New Holland, and which, in a o-reat mea- 
sure, can give us some idea of those formerly existing in Europe. 
* Professor linger seems unaware that in the milder parts of Ireland and 
England raanj Australian plants grow well in the open air, and are nninjured 
by frost. ETen at Kew there is a Encali/phts, which was planted in 1845, and 
is now abont twenty feet high, and which, without any protection, has s'tood 
twenty English winters uninjured hy frost and snow. But these facts do not 
invalidate his general argument ; on the contrarj, thej would rather tend to 
bear it out. — Ec. 
