VARIATIONS AND MOTIONS OF PLANTS. 103 



possibly produce seed ; their varieties have, therefore, to be 

 prolonged by propagation of cuttings, roots, and layers. 



Nothing is less constant in plants than double flowers, 

 which is fully exemplified in the Dahlia; as we may see on 

 the same plant, perhaps twenty flowers all differently formed : 

 some nearly single, with the organs of generation, as the male 

 and female parts, with a yellow centre; others approaching a 

 semi-double, and some a perfect double flower, until the va- 

 riety is termed " run out" which is to say, returned, to its 

 primitive state of a single flower. This sporting of flowers 

 is very different in plants of the same family ; for we see in 

 some plants that almost every flower is perfectly double, as, 

 for instance, in the Dahlia; the Countess of Liverpool gene- 

 rally forms a fine, clear, well-formed double flower; whilst 

 other varieties have occasionally a fine double flower; and 

 some, on the same plant, are semi-double, and the remainder 

 nearly single. The same affinity is observable in many kinds 

 of perennial plants, that produce double flowers. 



In annual flowers, as the Stock- gilliflower, the double 

 flowers are more perfect, but the duration is shorter: one 

 year only it can be said to continue, although it is often pro- 

 longed by cuttings, which are mostly of a sickly appearance. 

 Whatever may be the value of double flowers, certain it is, 

 that they, sooner or later, will cease to be in existence. 

 The primitive, or single flowers, are the only varieties that 

 can perpetuate the vegetable kingdom to the end of time. 

 The economy of nature in this case, as in all others, has 

 given a variation, that too much sameness may not cloy our 

 pleasure. We, for instance, in some double flowers, find 

 them continue their perfect character for many years unal- 

 tered, as the Double White Camellia; in others, we perceive 

 a continual variation for a few years, as in the Dahlia, and 

 then the primitive state again predominates. In other deno- 

 minations of plants, as annuals, a yearly variation from the 

 single to the double flower is observable, as in the Stock-gil- 

 liftower; whilst the primitive, or single flower, at all times 



