64 



THE planter's GUIDE. 



and attain the full development of its parts, thus realising 

 the absolute complement of life, to which it naturally 

 tends. In the same way, when these conditions are 

 stinted, the luxuriance of the plant is checked in the 

 ratio of that restraint, and the deficiency of the supply. 

 Where any one of the external conditions is partially or 

 inadequately supplied, the plant appears to make special 

 and even forced efforts to secure as much of the beneficial 

 influence as it can, and to accommodate itself to the 

 exigency of its situation. Thus, where light is admitted 

 only from a single point, a plant concentrates all its 

 powers in stretching towards the direction of the light. 

 Where light is shed all around, the plant throws out its 

 branches on every side. In conformity with this prin- 

 ciple, we find that, in the interior of a wood, where the 

 trees mutually impede the lateral admission of light, the 

 tendency of each is upwards ; and the consequence of 

 this tendency is, that the plant is thereby not developed 

 in its natural and perfect proportions, but is elongated, 

 or drawn up to an undue height. It displays its rami- 

 fication chiefly near the top ; while the imperfection of 

 its life is manifested in the whole character of its vege- 

 tation. In open exposures, on the other hand, the tree 

 develops its existence in full health and luxuriance. It 

 reaches a height such as the soil and situation admit, and 

 sufficient to allow the branches, which are thrown out on 

 every side, to expand their leaves freely to the sun. Not 

 being compelled to concentrate its effbrts, in securing a 

 scanty supply of one beneficial influence, all its propor- 

 tions are absolute and universal, not relative and parti- 

 cular. In such circumstances, therefore, it may be con- 

 sidered as in a full and natural state of perfection. 



Another condition of vegetable life appears to be an 

 adequate degree of heat. Within a certain range of 



