154 A, Fendler on Prairies. 
Art. XIX.—On Prairies ; by A. FENDLER.' 
In my botanical rambles I have seen Prairies, Llanos and Sa- 
vannahs of different magnitudes and in various stages of pro- 
gress; and, as I am assured that my suggestions on this subject, 
although they may not fully coincide with your views, woul 
be received in a kind spirit, 1 beg to make the following re- 
marks, 
same side, and exposed to the same wet weather, large tracts are 
entirely bare of forest. The forests, however, do,not gain on 
the savannahs, but from time to time the savannahs gain on the 
forests by a very simple agent, namely, that of /ire. 
Fire I consider by far the most powerful and the principe! 
great plains between Missouri and the Rocky mountains, on the 
llanos of Venezuela and the high savannahs of the mountainous 
district of the same country, I have seen the same forest-destroyer 
at work. In the region last named I had the rare opportunity 
of observing not only the gradual extension of the savannahs, = 
* From a letter to Professor Dana, dated Cambridge, Mass., Dec. 12, 1865. 
