But, however strong may be the disposition of the Dahlia to vary from its original structure, it is curious to observe how strictly it conforms to the laws by which such variations are controlled by nature. In altered structure all the changes take place from circumference to centre. The florets of the ray displace those of the disk, but the latter never attempt to occupy the ray; when a change occurs among the florets of the disk, they merely dilate and assume the colour of the ray, without changing their position or their peculiar form. So with the leaves; by a reduction of the lateral leaflet, till the terminal one only remains, simple foliage is substituted for that which was compound: but no case has been found in [p172] which the suppression of the terminal leaflet has taken place and the lateral ones have been preserved. In change of colour, too, there is a circumstance which demands consideration, and of which no explanation has yet been offered. It is not generally known, although long ago noticed by M. De Candolle, that among flowers, yellows will not produce blues, nor blues yellows, although both these primitive colours will sport into almost every other hue. Thus the hyacinth, the natural colour of which is blue, will not produce a yellow, for the dull, half-green flowers called yellow hyacinths, are, in our judgment, whites approaching green; the blue crocus will not vary into yellow, nor the yellow into blue; and the ranunculus and the dahlia, the natural colour of both which, notwithstanding the popular belief to the contrary, with respect to the dahlia, is, we believe, yellow, although they are the most sportive of all the flowers of the gardens, varying from pink to scarlet, and deepest shades of purple, have never yet been seen to exhibit any disposition to become blue. This subject offers a most amusing field for investigation, and would well repay the attentive consideration of the philosopher.
XV. _On the Cultivation of Camellias in an open Border_. By Mr. Joseph Harrison.
Mr. H. finds that the double red camellia, the double white, and the double striped, will bear an English winter if planted out when about two feet high, having been previously stunted in their growth by repeatedly stopping their leading shoots. For two winters the young plants are to be protected by a wooden screen fixed round them, and covered by a hand-glass, the whole being enveloped in mats; afterwards they require no other protection than to be guarded from heavy snowstorms, and to be assisted by a thick covering of old tan upon the ground in which they grow, to the distance of two or three feet from their stems. If this success has been met with in Yorkshire, what may not be expected in our more southern counties! On the 12th of March of the present year these camellias were not injured by a frost which did considerable damage to the common laurel.