On the Manageme7it of Peach Trees. 169 



the tree will be affected, and not another, but generally it is first 

 discoverable in the stem, and the young unripened shoots 

 that are attached to it ; and, when once the cellular tissue of 

 the stem is destroyed, the tree may be cut down, however 

 healthy may appear the branches, for no quackery in the 

 world will cure it. 



The relation existing between solar influence, and the veg- 

 etable kingdom, requires, also, our attention in connection 

 with this subject : this, however, is of less importance, in a 

 practical point of view, as it is an agency entirely beyond 

 our control ; nevertheless, so extraordinary is the influence 

 exerted by light and heat, over the vegetable creation, that 

 they may, in truth, be termed the prime essentials of its exist- 

 ence. When a plant is deprived of solar light, it exhibits a 

 half-organized, unduly elongated mass of matter, filled with a 

 superabundance of unassimilated juices ; if gradually restored 

 to the influence of the sun, it will assume its natural and ma- 

 ture form. Now, in this case, it is evident, that a close rela- 

 tion exists between light and vegetables, and that constituent 

 of which a considerable portion of every vegetable is com- 

 posed, namely, — carbonic acid, for here the former has mod- 

 ified the eflect of the latter upon the plant. The potency of 

 this modifying power is frequently exhibited in a very striking 

 manner, in those latitudes of the globe, which are character- 

 ized by great luxuriance of vegetation, and by periodical, or 

 accidental seasons of deep shade, or intense sunshine. I have 

 seen this effect also strikingly exhibited, while forcing vines 

 and peach trees, in the north of Scotland, during the dark, 

 gloomy days of December and January, when the sun would 

 be enveloped in a dense foggy atmosphere for weeks together. 

 I have seen this state of etiolation so great, that, upon the 

 restoration of the sun's rays, the leaves were unable to resume 

 their elaborative functions, and, consequently, drooped under 

 its influence ; a certain balance in the atmospheric constitu- 

 ents is essential to the successful development of vegetables, 

 and when that balance is destroyed, a change takes place in 

 the plants subjected to its influence. 



Plants will, in some measure, adapt themselves to circum- 

 stances, but not without producing certain changes in their 

 nature; but this may happen without producing any material 



VOL. XV. — NO. IV. 22 



