306 Changes of Timber and Flatits, bV. 



plant constitutes one eighth part of the timber of the 

 place. Though I can give no personal testimony in 

 support of this fact, I notwithstanding believe it to be 

 true. 



In new settlements in the southern states, and I pre- 

 sume the same thing occurs elsewhere, the weeds and 

 gramineous plants which gradually and imperceptibly 

 introduce themselves into cultivated farms, are entirely 

 diiferent from the native productions of the surrounding 

 countr)'. This is a fact which is familiar to every one. 

 Now the question very naturally presents itself, whence 

 are these various plants derived? Are they introduced 

 by man or his domestic animals from foreign places? 

 If so, from what places, in v/hat manner, and for what 

 purpose? These are points worthy of consideration,, 

 and, in my opinion, difficult of solution. For my own 

 part, I cannot hesitate to believe, that tliese plants are 

 a new and spontaneous production of the farms where 

 they appear; and that they are brought into existence 

 by the new order or state of things, introduced into 

 these farms by the instrumentality of clearing and cul- 

 tivation. 



Were it necessaiy to the purposes of this letter, I 

 could produce numerous instances of similar innova- 

 tions in the animal kingdom. But as these innovations, 

 though remotely, are not proximately connected with 

 agriculture, I shall forbear to swell, by dwelling on 

 them, a communication in which I have already too far 

 trespassed on your time, and I fear on your patience. 



Before concluding, however, suffer me to remark, 

 that though we have both been in search of similar facts, 

 I suspect we have been collecting them for dissimilar 



