XIX.] MORPHOLOGY. 233 



polypites, differing from the ordinary polj'pites very mnch Homo- 

 as flower-bxids differ from leaf-buds.^ (The polypite is the t°^g^p^^°4 

 morphological unit of the Hydrozoon, as the leaf-bud of Hydro- 

 is of the tree.) And in those cases where the generative 

 organ breaks off and swims away as a Medusa, it still 

 continues to be essentially a polypite, though greatly 

 modified, and as it were disguised. 



The relation between the leaf-buds and the flower-buds of flower- 

 of a tree is exactly the same as this. It is now universally "^^ plants, 

 recognised that the flower- bud does not fundamentally 

 differ from the leaf-bud; and that the flower consists of 

 parts which are essentially leaves, but modified to do 

 other work than that of the leaves.^ Thus the calyx-leaves, 

 the petals, the stamens, and the pistils, are all homologous 

 with the leaves and with each other. This is shown by 

 the history of their development from the bud, and is 

 confirmed by the fact that in monstrous or abnormal 

 flowers they all graduate the one into the other. The best 

 instance with which I am acquainted of correlation be- 

 tween leaf-bearing and flower-bearing axes — that is to say, 

 between the products of leaf-buds and of flower-buds — is 

 that presented in the umbelliferous order, which have TJmbelU- 

 somewhat feathery compound leaves, composed of small ^^^' 

 leaflets, and small flowers clustered together into those 

 beautiful regular " umbels," from which the order has its 

 name. This resemblance between the manner in which 

 the leaves and the flowers are each combined is a corre- 

 lation which it seems quite impossible to refer to any 

 adaptation of structure to function. The function of the 

 leaves is to decompose carbonic acid and water, and to 

 form organic compounds ; the function of the flowers is to 

 mature the seed ; and there is no such connexion between 

 those two functions as to make it necessary or useful that 



1 This is proved, not only by their morphology, hut hy the fact that the 

 detached generative organs, or Mediisse, efter maturing and parting with 

 the generative products, have been observed to root themselves and develop 

 into common polypites. (See the Eev. Thomas Hincks on the Development 

 of Zoophytes : Quarterly Journal of Science, July 1865, p. 416, note.) 



2 This is Goethe's well-known theory, awkwardly called the theory of 

 the metamorphosis of plants. 



