Nature and Causes of Variation in Plants. 417 



nmbel and the spike by arrest of the main axis or of the 

 flower stalks respectively. Suppression of both gives the 

 capitulum, and, as specialisation goes on, the convex 

 flower-bearing surface of the composite becomes flattened, 

 as in Dorstenia, and finally deeply hollowed, as in the fig. 

 (Plate Xiy. fig. A, 1-6). 



2. In simple flowers an indefinite number of modified 

 leaves is arranged round the axis, whose internodes are 

 suppressed. The first advance is to a definite number of 

 sepals, petals, stamens, and carpels in the arrangement 

 called hypogynous. A carrying on of the outer parts of 

 the axis gives the perigynous position to the stamens, and 

 the final form is the epigynous, where stamens, petals, and 

 sepals are all carried past the ovary, the carpels occupying 

 the inside of a pit instead of the outside of a cone (see 

 fig. B). 



Both these cases are clearly explicable by reference to the 

 familiar antagonism between reproduction and vegetative 

 growth (further analysed in the writer's recent paper on 

 " The Theory of Sex and Eeproduction " — cf. Uncyclopcedia 

 Britannica, article " Sex" — to its basis in the constructive 

 and destructive metabolism of protoplasm). We may view 

 in the same light the concave form of the spore-bearing 

 surfaces in many Fungi and Algae — for instance, Peziza or 

 Fucus (see fig. C) — and the emargiuate form of the fern 

 Prothallus, where the sexual organs appear (fig. E). 



Note also that the shortening and reduction in the 

 inflorescence of the Coniferas from fir-cone to yew-" berry " 

 is parallel to that of the phanerogams. The reduction of 

 indefinite to the various forms of definite inflorescence is 

 another change in the economy of the phanerogam. 

 Similar to this is the reduction and even loss of bracts, and 

 usually of petioles and stipules in the sepals. The com- 

 plete or partial loss of the calyx and petals is usually 

 considered degenerate ; but from the present economy 

 point of view, it seems a more complete specialisation for 

 reproduction. In getting rid of coloured and merely 

 attractive organs, and assuming wind fertilisation, the 

 vegetative system is still further reduced. 



The lessening in the number of stamens, carpels, and 

 ovules in all the more evolved orders of plants is a parallel 



