CHAPTER IV. 



Morphology under the Influence of the Doctrine of 

 Metamorphosis and of the Spiral Theory. 



1790-1850. 



The efforts of Jussieu, De Candolle, and Robert Brown were 

 directed to the discovery of the relationship between different 

 species of plants by comparing them together ; the doctrine of 

 metamorphosis founded by Goethe set itself from the first to 

 bring to light the hidden relationship between the different 

 organs of one and the same plant. As De Candolle's doctrine 

 of symmetry derived the different species of plants from an 

 ideal plan of symmetry or type, so the doctrine of metamor- 

 phosis assumed an ideal fundamental organ, from which the 

 different leaf-forms in a plant could be derived. The stem 

 came into consideration only as carrying the leaves, the 

 root was almost entirely disregarded. As the resemblance of 

 nearly allied species of plants suggests itself naturally and 

 unsought to the mind of the unbiassed observer, so also does 

 the connection between different organs of a leafy nature in 

 one and the same plant. Cesalpino called the corolla simply 

 a ' folium ' (leaf) ; he and Malpighi regarded the cotyledons also 

 as leaves ; Jung called attention to the variety of the leaf- 

 forms, which are found in many plants at different heights on 

 the same stem ; Caspar Friedrich Wolff, the first who bestowed 

 systematic consideration on the subject, declared in 1766, that 



