NOTICES OF BOOKS. 409 
of climate and soil, which are generally considered to exercise so much 
influence in the distribution of plants. With respect to the former, 
without denying the broad fact that some plants are adapted to tropical 
and others to temperate climate, he questions the applicability of this 
cause as an influential agent in limiting the distribution of plants 
within limited areas, and especially within North-west Germany, the dis- 
trict to which his investigations particularly refer. He even goes so 
far as to consider that the north-easterly line which bounds the areas 
of certain species, and which is usually considered to indicate a demar- 
cation between the more humid climate of Western Europe and the 
continental climate of the east, is in Germany more properly to be ex- 
plained by the trending of the land to the north as we advance to the 
eastward ; so that species, which descend from the high lands, have so 
much greater distance to travel by water in order to reach the sea the 
further east we go, on which account their northern limits naturally 
tend to arrange themselves in lines facing north-west. He then pro- 
ceeds to argue that there is something forced in the conclusion that 
species which extend for many hundred miles to the south and east, 
and are by no means restricted in altitude, and which grow with faci- 
lity under cultivation in all parts of Europe, should grow abundantly 
in Middle Germany, and stop abruptly at a line drawn through the 
towns of Bonn, Hanover, Stettin, although the climate of the tract to 
the northward of that line has a barely perceptibly less mean tempera- 
ture than the more southerly districts. This he finds to be the case 
with a very large number of German plants; and as he cannot believe 
that the climate alone could cause them so suddenly to disappear, he 
dismisses it entirely as an influential agent in regulating the distribu- 
tion of plants. 
The nature of the soil he is disposed to consider still less important, 
and he points out the many inconsistencies into which the advocates of 
the limitation of plants to peculiar soils are led by the great admixtures 
which exist in all soils, and by the occurrence of those plants, which in 
warm climates grow only on clay, in damp, humid, and cool climates on 
calcareous soils; and he comes at last to the conclusion, that, however 
the nature of the soil may affect the luxuriance of a plant, it can exer- - 
cise very little influence on its oecurrence or distribution. 
He then proceeds to explain in detail his own peculiar views, and to 
give at length the grounds by which he believes them to be supported ; 
VOL. V. 3G 
