220 AtmospJicric Changes. 



considerable size and age, as their decayed trunks testify. The extensive 

 forests then existing were sufficient to break the force of northers before 

 they reached the latitude of the Gulf States ; and, of course, the moist at- 

 mosphere maintained by these forests tended to equalize temperatures. 

 How great an influence these northers may exert on a southern climate, 

 even in the partially-wooded districts of the East, is plainly exhibited in 

 the devastation by frost at St. Augustine, Fla., on Feb. 9, 1835, '^vhen 

 orange-trees two feet in diameter, and a century old, fell victims. Now 

 this fruit is not considered sure above latitude 29°, though cultivated much 

 farther north in protected localities. The planting of forest-trees cannot be 

 too strongly advised: the subject is one of not merely local, but of na- 

 tional importance. It is, moreover, quite easy to prove it a profitable opera- 

 tion. But we Americans are at present very nomadic in our habits : we 

 occupy land for its immediate advantages, and are rarely inclined to com- 

 mence improvements that require half a century or more for their accom- 

 plishment. 



With regard to vegetable nosology, we can only say that too little is known 

 of the nature of vegetable life for a svstematic and theoretical treatment 

 of the diseases to which plants are liable. It may be that they possess the 

 faint foreshadowings of a nervous system, and are liable to other than 

 mere mechanical injuries. The microscope gives us, I believe, no direct 

 indications that such is the fact : but the curious action of certain so- 

 called narcotic gases, which cannot injure the tissues, and the effects pro- 

 duced by vegetable poisons, are difficult of explanation without admitting 

 a degree of nervous excitability. However this may be, we should remem- 

 ber that most of the curatives recommended are the results of blind ex- 

 periment, and that much difference of opinion exists as to their value, and 

 mode of application ; and, finally, that the old adage, " Prevention is 

 better than cure," is worth as much now as it ever was ; and that we shall 

 do well to protect our plants in every manner possible from all injurious 

 influences that may generate or develop disease. Z>. M. Balch. 



.Salem, Mass. 



