THE INFLORESCENCE, AND THE FLOWER 241 



For carrying this out, Secd-PhDits arc depeiidoit upon cxlcrual agencies, 

 sncli as loater, icind, or animal activitv. Moreover, as the Plant is 

 hxed in the soil and immobile, such agencies must be resorted to if 

 tlie ad\-antagc of intercrossing is to be secured. It is such considera- 

 tions as tliese which make intelligible the \-ariety and intrieacv of the 

 iornis which Flowers show. 



The fact that the flower is constructed lundamentally on the sanie plan as 

 the foliage shoot did not escape the attention of the early botanists. More- 

 over, they noted that it is uni-\-ersally preceded by some form of vegetative 

 slioot in the individual life of the higher plants. In annual plants this is 

 obvious enough : it is only after the establishnrent of the leafy plant that the 

 flower-buds nrake their appearance. But in the case of many of the plants 

 that expand their flowers in the early spring the matter is not so simple, and 

 one is apt to forget the swollen underground parts from whose stores the 

 flowers draw their material. It is needless to elaborate by examples the 

 simple fact that in all cases nutrition must precede propagation. It was this 

 fact that formed the foundation of Goethe's theorv of Metamorphosis. He 

 recognised under this name the process by which one and the same organ, for 

 instance the leaf, presents itself to us in various modifications, such as the 

 foliage leaf, sepal, petal, or stamen. He distinguished as " progressive meta- 

 morphosis " those changes of t^-pe of the appendages which proceed from the 

 cotyledons or seed-leaves, through the foliage region and bracts to the flower, 

 and finally to the perfected fruit. On the other hand he designated as " retro- 

 gressive metamorphosis " that process by which the succession appears 

 reversed ; as for instance in abnormal or doubled flowers, when a stamen or 

 a carpel develops as a petal, or even as a foliage leaf. These general ideas 

 of the relation of the vegetative and floral regions were amplified and made 

 more definite by later writers, and were for a long time widely held. Thus it 

 became a general belief that the flower had resulted from changes wrought in some 

 pre-existent vegetative shoot. 



So long as we direct our attention solely to the Flowering Plants this opinion 

 might stand. But as the nineteenth century drew on, knowledge of the lower 

 forms greatly increased, especially in the case of such plants as the Ferns and 

 Club-Mosses, This has supplied the material necessary for a revised theory of 

 the origin of the flower. Checked by these comparisons we may now figure, on 

 a basis of fact rather than of semi-poetical surmise, how the flower as distinct 

 from the vegetative region originated in the higher plants. The main point 

 to bear in mind is that the propagative function must have recurred in each 

 fully completed hie-cycle throughout descent. Hence the production of 

 sporangia was never an innovation, and they cannot at any time in the course 

 of descent have been imposed upon a pre-existent vegetative system, as 

 Goethe's theorv would assume. The facts suggest that the whole shoot of 

 relatively primitive Vascular Plants luas non-specialised. It served general 

 purposes, both for vegetation and propagation. But in the course of evolution of 

 higher types differentiation took place, so that a certain region became exclusively 

 vegetative, while another produced sporangia. Thus a theory of Segregatiox 

 takes the place of a theory 0/ Met.\morphosis. The vegetative phase naturally 



