6 Description of the Landes of Acquitania. 
the migrations of man or animals, and also with localities, which we 
can scarcely explain. 
The physical characters of the plants themselves, as Turpin has 
beautifully remarked, will also vary with their situation. Not equal- 
ly brilliant every where, vegetation, gay and smiling on the bor- 
does of rivulets, elegant and graceful in the vallies, rich and ma- 
jestic on the great plains, is no longer the same when it shows it~ 
self on the burning rock, or fights against alpine snow. A vast ex- 
tent of plain in the same country, and in the same position, will 
produce pretty nearly every where the same plants ; but if this plain 
is intersected by forests, furrowed by vallies, watered by rivulets,— 
if the soil is variable, humid, sandy, or chalky, the mass of its plants 
will be found to vary equally with each change of situation or of soil. 
On leaving Paris by any of the south-westerly roads, the physi- 
cal characters of the country consist of a series of vallies, which 
seem to sweep consecutively round one another, bearing generally 
tributary streams to the Seine. From Etampes to Orleans the 
horizontality of secondary strata gives rise to an extensive plain, 
though in no point uncultivated or barren ; to the west the town 
of Chartres is visible, on its approach, at a great distance. The 
uniformity is broken by the course of the Loire, and the cropping 
out of the oolitic series, which, crossing the channel north of the 
Seine, appears in the vicinity of Boisgeancy, coursing round the 
tertiary basin of Paris in a circular manner, and re-appearing at 
intervals, with the chalk formation, beyond the most northerly de- 
partments of France. This series gives origin to the first exten- 
sive vineyards in the Tourraine and Bourbonnois. The depart- 
ment of La Charente, traversed in all directions by rivers and rivu- 
lets, formed of hills and undulating tracts, covered with verdant 
forests, which stretch into the plains below, presents a smiling 
and rich appearance. Some extensive heaths are first met with in 
the Charente Inferieure, situated on the sides of hills or sandy 
plains. They present, however, a fine cover of trees and shrubs, 
intermingled with Erice and Leguminose of luxuriant growth, 
becoming more barren only near St. André de Cubzac, where they 
bear evident marks of a most unproductive soil. The Mantis ora- 
toria is first met with on these plains,* where also grows the Erica 
- ciliaris, and the Datura Stramonium amidst the stony parts. 
A similar degree of elevation assigns to extensive plains a mean 
temperature generally lower than the annual heat of the latitude 
in which they occur; while the seasons are liable to less abrupt 
transitions, and the diurnal variations, and annual mean of the ba- 
rometer, are diminished in the extent of their fluctuations. It 
may easily be conceived that, with the exception of the Landes, 
the variety of aspect, in the departments of the west, influences 
much the nature of the vegetation ; and a simple inspection of the 
map attached to the “ Flore Francoise,” is sufficient te show that 
the plants of the southern provinces appreach nearer to the north 
* The Phasma Rossii is met with in the vicinity of Orleans. 
