178 The Natural Syskm of Botany. 



have examined, and it is on this difference that the Linriap 

 orders of the corresponding group are founded. Instead f 

 having a pod nearly as long as broad, called a Silicic lib 

 that of the Shepherd's Purse, that of Cabbage, and Turn' 

 and others, is very long and slender, and is called a Silim!! 

 This difference is not made use of in dividing the Natur 1 

 Order, however, but the genera, (which are so numerous ast 

 make a division necessary,) are arranged in groups, founded 

 on certain minute distinctions in the structure of the embryo 



The Cruciferae are all herbaceous, and most of them aunual 

 plants. It is remarkable that while the characters of the order 

 are so constant, those of the individual are liable to so great 

 variation, under the influence of cultivation. This is shown in 

 those which are cultivated for the beauty of their flowers, such 

 as the Stock and Wall flower. Both these, says an often 

 quoted authority, however lovely in their wild and single state 

 are chiefly cultivated when their flowers have become what is 

 called double, that is to say, when the parts which are usually 

 stamens, and pistils, and sepals, are all transformed into petals* 

 by which means, the quantity of gaily colored parts is much 

 augmented. It may be a subject of wonder how these double 

 flowers are increased, for if the stamens and pistils are con- 

 verted into petals, it would seem that no means are left for 

 multiplying the race. This would doubtless be so, if all the 

 stamens and pistils were really thus transformed ; but among 

 many flowers, some are found in which a perfect stamen or 

 two remain ; and others, in which a perfect pistil or two can 

 be found. If the stigmas of the latter are touched with 

 the pollen of the former, ovules are fertilized, and seeds are 

 produced, which will grow into other plants, the flowers of 

 which will be as double as those of their parents. No one 

 knows why double flowers should be capable of being thus 

 perpetuated ; it seems as if any tendency which is once given 

 to a plant, may be carried on from one generation to another, 

 by a careful attention to stop all disposition to depart from the 

 new character. In the Stock, any plant that produces flowers 

 less double than usual, must have a tendency to depart from 

 the double state, and, therefore, should not be allowed to bear 

 seed, or to influence the seeds borne by others, but should be 



