PLANT METAMORPHOSIS 59 



whims of the imagination have taken the place of earnest 

 and acute investigation." 



In anatomy Grew and Malpighi were still supreme, 

 for Caspar Wolff's Theoria Gejierationis, published in 1759, 

 can scarcely be considered as of primary importance. 

 Like Goethe he concerned himself largely with the doctrine 

 of metamorphosis and investigated the origin of foliar 

 appendages at the " punctum vegetationis " of the stem. 

 " In the entire plant," he says, " whose parts we wonder 

 at as being, at the first glance, so extraordinarily diverse, ■ 

 I finally perceive, after mature consideration, and re- 

 cognise 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." You 

 will note one marked difference between the methods of 

 Goethe and of Wolff. The former arrived at his doctrine 

 of metamorphosis by prolonged meditation on the 

 appendicular organs of the vegetative and reproductive 

 branches, while Wolff reached his conclusions by a close 

 examination of the mode of development of these organs 

 from primary meristem. Goethe's method was deductive, 

 while Wolff's was inductive. It is said that when Goethe 

 explained his doctrine to Schiller the latter commented, 

 " this is not an observation, it is an idea." 



In physiological research, on the other hand, the 

 closing years of the century were particularly rich and 

 well worthy of your earnest study and attention. 



You will remember how, in 1686, Ray had admitted 

 that the doctrine of sexuality in plants was " extremely 

 probable " but required yet more decided proofs, and 

 how Camerarius a few years afterwards pro\dded some 

 of these proofs by his experiments on castrated flowers. 

 A further and important stage in the solution of the 

 problem was reached when Koelreuter, about 1760, 

 discovered the function of nectar and the part played by 

 insects and also by wind in flower pollination. Koelreuter 

 studied the structure of the pollen grain and identified 



