42 The Science of Life. 



" appendicular organs", whether ordinary leaves or 

 floral parts, have a similar mode of development at the 

 growing" point (punctum vegetationis] of the stem. It 

 was thus inductively that he reached the following con- 

 clusion (1767): "In the entire plant, whose parts we 

 wonder at as being, at the first glance, 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." 

 What is particularly significant in Wolffs work is 

 that he sought in the study of development to find a 

 secure basis for his theory that the parts of the flower 

 are transformed leaves. " If", he said, " the organs of 

 a plant, with the exception of the stalk, are thus refer- 

 able to the leaf, and are mere modifications of it, a theory 

 showing the manner in which plants are generated is 

 obviously not a very difficult one to form, and at the 

 same time the course is indicated which we must follow 

 in propounding it. It must first be ascertained by 

 observation in what way the ordinary leaves are formed, 

 or in other words, how ordinary vegetation takes place, 

 on what basis it rests, and by means of what powers it 

 is brought into existence. Having gained this know- 

 ledge, we must investigate the causes which so modify 

 the general mode of growth as to produce, in the place 

 of leaves, the parts of the flower." His own peculiar 

 theory was that the change from a foliar to a floral 

 organ was due to a diminution of vegetative power 

 (vegetatio languescens). 



More than twenty years after Wolff, Goethe reached 

 a similar conclusion on independent lines. One may 

 doubt the accuracy of his self-analysis when 

 he said that he had been more influenced by 

 Linnaeus than by any one save Shakespeare and Spinoza, 

 but it is certain that he was stimulated by the Prolepsis. 

 For several years before he published his famous essay 

 he was pondering over the problem of the flower, and 

 it was doubtless this persistence "through long prose- 

 cuted studies " which enabled him to persuade himself 

 that he had reached his conclusion inductively. The 



