PHYLLODT OF THE FLORAL WHOELS. 307 



As another carious instance a remarkable form of the 

 Sun-dew, Drosera rotundifolia, may be allnded to here, as 

 throwing additional light upon the origin of ovules. It has 

 been described and figured by Naudin,* and also by Plan- 

 chon.'l" In this monstrosity the ovular coats were represented 

 by " tentacles." These, as is well known, are not epidermal 

 trichomes, but structures issuing from branches arising from 

 the fibro-vascular cords of the leaf, and are therefore strictly 

 homologous with the "funnels " on cabbage leaves. J 



The conclusion, therefore, which seems deducible from 

 the foregoing observations is that an ovule is simply an 

 appendage (not a bud) to the fibro-vascular cord of the 

 margin of the carpel, and under monstrous conditions can 

 grow into foliaceous excrescences to the carpellary leaf. It 

 is not, therefore, axial in its character. Since all that is 

 required to start from is a fibro-vascular cord, this may be 

 furnished by any cord, even the mid-rib ; and such is the case 

 in some monstrous states of Primula, in which rudiments of 

 ovules are found on the mid-ribs as well as on the margins of 

 separate carpels. 



As the " funnels " on the mid-ribs and lateral veins of 

 cabbage leaves are due to an abnormal condition of hyper- 

 trophy, so ovules I consider as arising in a similar way, and 

 take them to be due to the same influence, though of course 

 it is normal in their case. The very presence of the large 

 cords running up the margins of carpellary leaves, direct from 

 the axis below, — being often, indeed, larger than the dorsal 

 cord, — which then ramify, not only into each ovule, but often 

 backwards within the carpellary walls till they reach and 



* -47111. des Sci. Nat., 2° s^r., vol. xiv., p. 14. 

 t Ibid., 3' ser., vol. ix., p. 86, tab. 5, 6. 



X The " pitchers " of Nepenthes, perhaps, originate in much the 

 same way, from the original water-gland at the apex of the leaf. 



