CHAPTER II 

 THE THEORY OF METAMORPHOSIS 



THE controversy which occupied us in the last chapter was 

 not unnaturally accompanied by a re-examination of the 

 theory of metamorphosis, which had become very generally 

 accepted since the days of Goethe and of Wolff. By both 

 these writers it was held to be concerned almost entirely 

 with the leaves and stem. Wolff presented it in the follow- 

 ing terms : ' In the entire plant, whose parts we wonder 

 at as being at the first gltfnce so extraordinarily diverse, 

 I finally perceive after mature consideration, and recognize 

 nothing beyond leaves and stem (for the root may be 

 regarded as a stem). Consequently, all parts of the plant 

 except the stem are modified leaves.' Goethe about thirty 

 years later spoke of certain exterior parts of plants passing 

 into the form of adjacent parts either wholly or in a greater 

 or less degree, so that it is possible to look upon a stamen 

 as a folded petal, or a petal as an expanded stamen. His 

 ideas were not put before his readers very clearly, and 

 left them sometimes uncertain whether he considered all 

 leaves modifications of some ideal or theoretical form, 

 or whether he held that a structure commencing its develop- 

 ment in some particular direction might be actually diverted 

 into another, and become something quite different from 

 what it would have become, had its development not 

 been interfered with. The former view, on the whole, 

 met with more general support at the outset. Many years 

 nearer the opening of our period we find it supported and 

 interpreted by Alex. Braun, who recognized as modifications 

 of the hypothetical leaf, cotyledons, cataphylls or scales, 

 foliage leaves, the leaves of the perianth of the flower, 



GREEN E 



