Vegetable Morphology. 41 



The two names most intimately associated with the 

 doctrine of metamorphosis are those of the embryologist 

 Wolff and the poet Goethe, who arrived at the same 

 conclusion the homology of appendicular organs by 

 very different paths; but it is important to notice that 

 previous attempts had been made to discover connec- 

 tions between the various structures which spring from 

 the axis of a flowering plant. Thus Cesalpino had 

 called the corolla simply a leaf ("folium"); he and 

 Malpighi had also regarded the cotyledons as leaves; 

 and the keen-sighted Joachim Jung had analysed the 

 plant-body into root and shoot, and the latter into stem 

 and leaf. As Prof. Vines notes, Jung "revealed strik 

 ing morphological insight", and "grasped the funda- 

 mental ideas of morphology", but his works, which were 

 not published till after his death (Isagoge Phytoscopica, 

 1678, &c.), had almost no influence. Linnaeus also had 

 an idea of the equivalence of the appendicular struc- 

 tures, as suggested, for instance, in the aphorism Prin- 

 cipium florum et foliorum idem est. He developed his 

 views in two dissertations entitled Prolepsis Plantarum 

 (1760 and 1763), but these were obscured by a minor 

 physiological theory, according to which the flower was 

 regarded as an anticipation (prolepsis} of several years' 

 growth of vegetative shoots. He did, however, refer 

 all the parts of the flower to leaves, arguing from the 

 numerous transitions, both normal and pathological, 

 that the parts must be homologous. Only homologous 

 parts, he said, can thus change into one another; "the 

 liver cannot become the heart, nor the heart the stomach". 

 Wolff's Theoria Generationis was published the year 

 before the first Prolepsis essay, but Linnaeus had made 

 similar suggestions in his Sy sterna Naturce (1735) and 

 in his Philosophia Botanica (1751). 



Caspar Friedrich Wolff, who is best known as the 

 founder of the embryological doctrine of Epigenesis, 

 was led to a study of the development of Wolff 

 plants by a desire to test the theory which 

 he had reached from a zoological basis. He investi- 

 gated the leaf-bud of the cabbage, the flower-bud of 

 the bean, and the like, and showed that the various 



