82 PERIOD III. 



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the organs of the flowering plant one structure repeated 

 again and again, which gradually attained, as by the 

 steps of a ladder, what he called the crowning purpose 

 of nature — viz., the sexual propagation of the race. 

 This fundamental structure was the leaf. The proposi- 

 tion that all the parts of the flower are modifications of 

 the leaf he defended by three main arguments — viz., 

 (i) the structural similarity of seed-leaves, foliage- 

 leaves, bracts, and floral organs ; (2) the existence of 

 transitions between leaves of diff'erent kinds ; and 

 (3) the occasional retrogression^ as he called it, of 

 specially modified parts to a more primitive condition. 

 These lines of argument were illustrated by many well- 

 chosen examples, the result of long and patient obser- 

 vation. Goethe did not, however, fortify his position by 

 the likeness of developing floral organs to developing 

 foliage-leaves, which had been Wolff''s starting-point. 

 He arrived independently at Wolff"'s opinion that the 

 conversion of foliage-leaves into floral organs is due to 

 diminished nutrition. 



Linnaeus's exposition of the nature of the flower had 

 been read attentively by Goethe, who must have 

 remarked that the conversion of organs to new uses was 

 there described as a metamo7'phosis. That word had 

 been, long before the time of Linnaeus, appropriated to 

 a particular kind of change — viz., an apparently sudden 

 change occurring in the life-history of one and the same 

 animal. It was therefore unlucky that Goethe should 

 have been led by the example of Linnaeus to employ the 

 word in the general sense of adaptation to new purposes. 

 He did not, however, expressly compare flower-pro- 

 duction with the transformation of an insect, as Linnagus 

 had done. 



The reception of Goethe's Metamorphosen der Pflanzen 



