196 
EEVIEWS. 
sum of a thousand others whose subtle influences no man can 
estimate. Considering all these circumstances, strongly as we are 
inclined to adopt M. De Candolle’s view of the diminution of the 
Turkey Oak, it is impossible to assign to his arguments the positive 
value he does. 
The case of the Beech is far better argued. 
The Beech invades the forests of Denmark and Germany, where 
it supplants the Conifers, Birch and Oak. M. Yaupell attributes 
this to—1. a desiccation of the soil (perhaps due to the advances of 
cultivation) ; 2. to a preparation of the soil by the leaves of other 
trees; 3. to the Beech growing well under the shade of Birch and 
Pines, whilst nothing will grow under its shade. 
M. De Candolle makes much of the obstacle presented by arms 
of the sea, in limiting the migration of plants, and especially of 
large trees, such as Cupuliferse. He says: “ The extension of the 
areas of a Cupuliferous plant, by the transport of its seeds across an 
arm of the sea, should be regarded as impossible # and he proceeds 
to observe that the present geographical distribution of species may 
fix the geological date of their extension in certain directions, or, in¬ 
versely, the date of the separation of certain islands from their neigh¬ 
bouring continents. Thus he continues : “ The Beech area extends 
westwards; that tree, though becoming more abundant towards the 
western parts of Europe, did not grow in Holland at the date of the 
conquest of that country by the Bomans; it is wanting in the sub¬ 
merged forests of the Channel; its being indigenous in Great Britain 
and Ireland is doubted, on the strength of a remark of Caesar’s, and 
on the fact of its rarity except in plantations; nor is it found in 
English peat-bogs, where the Pine, Oak, and other trees abound: 
hence the ancient home of the Beech should be regarded, as M. 
Vaupell maintains, as the mountain region of Central Europe.” 
The Beech cannot withstand the heats and droughts of the plains 
of S. Europe; it is found in the mountains of Sicily above 3000 feet, 
and in Corsica, but not in the far loftier mountains of Sardinia, the 
Erench Atlas and the Sierra Nevada, which may be due to the dry¬ 
ness of the chains ; so that the only conclusion M. De Candolle can 
draw is, that the establishment of the Beech in Sicily and Corsica 
antedates the period of the separation of these islands from the con¬ 
tinent on the north. The Beech is absent as a native in the Azores 
and Madeira, but flourishes where introduced ; whence he judges that 
those islands were separated from Europe before the Beech migrated 
so far westward. Lastly, he says, the Beech cannot always have been 
absent on the plains of Southern Europe, for it follows from its 
being found sporadically on the Pyrenees, in Corsica, on Etna and the 
* M. De Candolle is probably not aware that five plants of Entada giyantiloba 
were raised at the Royal Gardens, Kew, from seeds collected on the shores of the 
Azores, whither they had been transported by the Gulf stream from South 
America. 
