ox Goethe's scientific reseaeches. 37 



cessively-developed stem-leaves exhibit, by the way in 

 which the first simple root leaflets are replaced by a series 

 of more and more divided leaves, till we come to the most 

 complicated. 



He afterwards succeeded in discoveringf the transforma- 

 tion of stem-leaves into sepals and petals, and of sepals 

 and petals into stamens, nectaries, and ovaries, and thus 

 he was led to the doctrine of the metamorphosis of plants, 

 which he published in 1790. Just as the anterior extre- 

 mity of vertebrate animals takes different forms, becoming 

 in man and in apes an arm, in other animals a paw with 

 claws, or a forefoot with a hoof, or a fin, or a wing, but 

 always retains the same divisions, the same position, and 

 the same connection with the trunk, so the leaf appears 

 as a cotyledon, stem-leaf, sepal, petal, stamen, nectary, 

 ovary, &c., all resembling each other to a certain extent 

 in origin and composition, and even capable, under 

 certain unusual conditions, of passing from one form into 

 the other, as, for example, may be seen by any one who 

 looks carefully at a full-blown rose, where some of the 

 stamens are completely, some of them partially, changed 

 into petals. This view of Groethe's, like the other, is now 

 completely adopted into science, and enjoys the universal 

 assent of botanists, though of course some details are still 

 matters of controversy, as, for instance, whether the bud 

 is a single leaf or a branch. 



In the animal kingdom, the composition of an indi- 

 vidual out of several similar parts is very striking in the 

 great sub-kingdom of the articulata — for example, in 

 insects and worms. The larva of an insect, or the cater- 

 pillar of a butterfly, consists of a number of perfectly 

 similar segments ; only the first and last of them differ, 

 and that but slightly, from the others. After their 

 transformation into perfect insects, they furnish clear and 

 simple exemplifications of the view which Groethe had 



