_Begonia_ may be instanced. In _B. rigida_ the flowers, various in their attitudes, are in their more conspicuous characters radial: though there is a certain bilateralness in the calyx, the five petals are symmetrically disposed all round. _B. Wageneriana_ furnishes two forms of flowers. On the same individual plant may be found radial flowers like Fig. 242, and others, like Fig. 243, which are merging into the bilateral. More decided is the bilateralness in _B. albo-coccinea_, Fig. 244; and still more in _B. nitida_, Fig. 245. While in _B. heracleifolia_, Fig. 246, the change reaches its extreme by the disappearance of the lateral petals. On examining the modes of growth in these several species, they will be seen to explain these changes in the manner alleged. Even more conclusive are the nearly-allied transformations occurring in artificially-produced varieties of the same species. _Gloxinia_ may be named in illustration. In Fig. 247 is represented one of the ordinary forms, which shows us bilateralness of shape along with a mode of growth that renders the conditions alike on the two sides while different above and below. But in _G. erecta_, Fig. 248, we have the flower assuming an upright attitude, and at the same time assuming the radial type. This is not to be interpreted as a production of radial symmetry out of bilateral symmetry, under the action of the appropriate conditions. It is rather to be taken as a case of what is termed “peloria”--a reversion to the primitive radial type, from which the bilateral modification had been derived. The significant inference to be drawn from it is, that this primitive radial type had an upright attitude; and that the derivation of a bilateral type from it, occurred along with the assumption of an inclined attitude. We come now to a group of cases above referred to, in which radial symmetry continues to co-exist with that constant lateral attitude ordinarily accompanied by the two-sided form. Two examples will suffice: one a very large flower, the Hollyhock, and the other a very small flower, the Agrimony. Why does the radial form here remain unchanged? and how does its continuance consist with the alleged general law?