THEORIES OF ORGANIC EVOLUTION 



another colored part is raised with the corolla, and the 

 leaf is thus torn in two. 



" The relationship between the petals and stamens is 

 very close. In some instances nature makes the transi- 

 tion regular e.g., among the Canna and several plants 

 of the same family. A true, little -modified petal is 

 drawn together on its upper margin, and produces a 

 pollen sac, while the rest of the petal takes the place of 

 the stamen. In double flowers we can observe this 

 transition in all its stages. In several kinds of roses, 

 within the fully developed and colored petals there ap- 

 pear other ones which are drawn together in the middle 

 or on the side. This drawing together is produced by a 

 small weal, which appears as a more or less complete 

 pollen sac, and in the same proportion the leaf ap- 

 proaches the simple form of a stamen. 



" The pistil in many cases looks almost like a stamen 

 without anthers, and the relationship between the for- 

 mation of the two is much closer than between the 

 other parts. In retrograde fashion nature often pro- 

 duces cases where the style and stigma (Narben) become 

 retransformed into petals that is, the Ranunculus 

 Asiaticus becomes double by transforming the stigma 

 and style of the fruit-receptacle into real petals, while 

 the stamens are often found unchanged immediately 

 behind the corolla. 



" In the seed receptacles, in spite of their formation, 

 of their special object, and of their method of being 

 joined together, we cannot fail to recognize the leaf 

 form. Thus, for instance, the pod would be a simple 

 leaf folded and grown together on its margin ; the siliqua 

 would consist of more leaves folded over another; the 



US 



