s 
Origin, Extension and pean of Prairies. Al 
out almost any family of trees. When the cane has driven out every 
tree and has acquired exclusive possession, it then begins to experi- 
ence the consequences of-exposure, without the shelter from the 
sun’s rays which is afforded by the trees. ‘The influence of the sun 
upon a cane-brake, unprotected by the trees, will in time produce 
the destruction of both stalk and root, by which means the land will 
fail to be occupied again by cane, until it has been covered anew 
with trees. Under favorable circumstances, the seeds of grass are 
always at hand, as well as those of trees; but the grass ‘is quickest 
to shoot and grow, and will soon afford a dry carpet, which, if set on 
fire at the proper time, will readily burn and destroy any young.trees — 
that had sprung up; the grass will now continue to increase in quan- 
tity and to:improve in quality as the cane-roots are decomposed and 
the annual fire is continued. But, on the other hand, if the firing is 
not carried on, the trees will, in a very few years, by their shade, 
exclude the grass; and should the land be adapted to the kind of 
trees that spontaneously appear, they may become so thickly set, as 
to form such a complete barrier to the sun and light, that even the 
cane will be kept from returning, and can regain its former residence 
only by taking hold at the time the trees are exchanging places; as, 
for instance, when one family, composed of ‘such trees as usually 
accompany each other, are becoming thinned by death, and thereby 
_ making room for another to occupy the land. 
There is no fact that can be better established than that prairies 
are formed, and are now forming, by the operation of wind and fire. 
Very abundant proof. was exhibited to the writer, more than twenty 
eight years ago, when making a pedestrian journey through the dis- 
tant and extensive regions of the west. He has seen the prairie in 
all its stages; he has seen the pees at work upon the forest. 
He has seen places where the inraad had been made only the year 
before ; where the grass stood bit "it Milly on the ground, and where 
it had Spesitsaie sufficiently luxuriant to burn. the first. 
ing took place, the timber was, in some places, partly consumed, and 
in other places altogether burnt off, leaving holes in the ground, made 
by the action of the fire upon the trees, which were burnt when stand- 
ing, and thus the stump part was consumed beneath the surface of the 
_ earth. 
When a hurricane rakes a an inroad upon a forest, the rays of the - 
sun are then admitted to the earth, and this at once affords an oppor- 
tunity for the = to = up; = if the land is rich and the sun 
Vou. XXUL— 
