352 ORGANOGRAPHY. 



Section 7. — The Theoretical Structure, or General 

 Morphology of the Floaver. 



Having now taken an extended view of the different organs 

 of the flower, we are in a position to examine in detail the theory 

 which has been kept constantly in view in their description, 

 namely, that they are all modifications of one type, — the leaf. 

 The g'enn of this theory originated with Linngeus, but the merit 

 of having first brought it forward in a complete form is due to 

 the poet Goethe, who, as far back as 1790, published a treatise 

 On the Metamorphoses of Plants. The appearance of this trea- 

 tise at once drew the attention of botanists to this subject, and 

 it is now universally admitted, that all the organs of the flower 

 axe formed upon the same plan as the leaf, and that they owe 

 their difl"erences to especial causes connected with the functions 

 which they have severally to perform. Thus the leaf, being de« 

 signed especially to elaborate nutriment for the support of the 

 plant, has a form, structure, and colour which is adapted for 

 that purpose; Avhile the parts of the flower being designed for 

 the purjjose of reproduction, have a structure and appearance 

 which enable them to perform their several functions. 



It was formerly said, that the parts of the flower were meta- 

 morphosed leaves, but this is stating the question too broadly, 

 because they have never been leaves; they are to be considered 

 only, as homologous parts or parts of the same fundamental nature, 

 that is, " constructed of the same elements arranged upon a 

 common plan, and varying in their manner of development, not 

 on account of any original diff"erence in structure, but on account 

 of special, local, and predisposing causes: of this plan the leaf is 

 taken as the type, because it is the organ which is most usually 

 the result of the development of those elements, — is that to which 

 the other organs generally revert, when, from any accidental 

 disturbing cause, they do not sustain, the appearance to which 

 they were originally predisposed, — is that in which wc have the 

 most complete type of organisation," * and, moreover,— is that 

 Avhich can always be distinctly traced by insensible gradations 

 of structure into all the other parts. 



Having defined the general nature of the doctrine of Morplio- 

 logy, or that doctrine which investigates the various alterations 

 of form, &c., which the diff'crcnt parts of i)lants undergo in 

 order to adapt them to the several purposes for which they were 

 designed, wc proceed to prove that the i)arts of a flower are homo- 

 logous with leaves. In doing so, we shall examine the several 

 parts of the flower, both as they exist in a natural condition, 

 and in an abnormal state, commencing witli the bract, and then 

 ])rocecding in a regular manner with the diflcrent whorls of tho 

 flower, according to their arrangement from without inwards. 



* Lindley's Introduction to Botany. 



