212 VARIABLENESS 



power, by which form and organization are given to 

 substances apparently homogeneous, and destitute of 

 any particular configuration. Thus the fluid of the 

 egg changes to an organized animal body ; and thus 

 the blood and lymph, in the stump of an amputated 

 limb, become occupied with muscles, blood-vessels 

 and nerves, like the corresponding parts of the ani- 

 mal frame. Analogous facts, though less evidently 

 perceptible, are to be traced, without any uncertainty, 

 in the vegetable body. In the latter we may per- 

 haps, even more positively than in animals, satisfy 

 ourselves of the influence of particular circumstances, 

 in causing a different organization. Many a plant 

 may be extensively increased by cuttings or by roots, 

 for a succession of years, without producing any seeds, 

 or even the least rudiments of flowers. But if*one or 

 more of these cuttings or roots should be treated dif- 

 ferently from the rest, with respect to their allotted 

 portion of water, heat, or nourishment, such may very 

 probably bear flowers and seeds, as happened by 

 chance to the Solandra at Kew ; see Introd. to Botany, 

 chap. 14. In other words, the same organic matter 

 which, under the influence of certain causes, assumes 

 the form of branches and leaves, in different cir- 

 cumstances becomes flowers and seeds. If we trace 

 this indefinite power of organization a step further, 

 we perceive that the materials of a perfect flower, de- 

 stined to form seed, are sometimes transformed into 

 a mutilated or. an over-luxuriant one, consisting of 



