OEGAXS OF EEPEODrCTIOX. 3i3 



Rumex {fig. 761), when it is directed towards the apex of the 

 pericarp ; inferior or descending when it points to the base ; 

 centripetal if turned towards the axis or centre of the pericarp ; 

 and ceoitrifugal if towards the sides. The above relations of 

 the embryo to the other parts of the seed, and to the pericarp, 

 are sometimes of great practical importance. 



Section 7. — G-exeeal jMoephologt, oe the Theoeeticae Stbuc- 



TEEE OF THE f LOW^ER. 



Having now taken a comprehensive view of the different or- 

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

 theory which has been kept constantly in view in their descrip- 

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

 leaf. The germ of this theory originated with Linneeus, 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 

 Goethe's treatise at once drew the attention of botanists to this 

 subject, and it is now universally admitted, that all the organs 

 of the flower are formed upon the same plan as the leaf, and that 

 they owe their differences to especial causes connected with the 

 functions which they have severally to perform. Thus the leaf, 

 being designed especially to elaborate nutriment for the support 

 of the plant, has a form, structure, and colour which are adapted 

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

 for the purpose 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 horaologous parts to leaves, or parts of the same funda- 

 mental nature, that is, as well stated by Lindley, "constructed 

 of the same elements aiTanged upon a common plan, and vary- 

 ing in their manner of development, not on account of any ori- 

 ginal difference 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 or- 

 gans generally revert, when, from any accidental disturbing 

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

 originally predisposed, — and moreover, is that in which we have 

 the most complete type of organisation," and, we may add, 

 is that which can always be distinctly traced by insensible 

 gradations of structure into all the other parts. 



Having defined the general nature of the doctrine of Morpho- 

 logy, or that doctrine which investigates the various alterations 



