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Show 34 VARIETIES IN PLANTS [Cb. II. of the race wh l.C h occupi· ed the hiOo 'hly-.m anu.r ed tract; f01·, if these accidents so continually happen m spite of us,. among the culm. ary van.. e t't es, it is easy to see. ho. w soo. n this cause might obliterate every marked singulanty m a wJld state. ne s1' d es, 1't 1. s well -known that a1thouQ'-': h the pampered races which we rear in our gardens for use or ornament, may often be perpetuated by s~ed, yet they rarel! p~od.u~e seed in such abundance, or so prolific in quality' as wild mdlVIdual~; 80 that, if the care of man were withdrawn, the most fer~1le variety would always, in the end, prevail over the more slen~. Similar remarks may be applied to the double flowers whiCh present such strange anomalies to the botanist. The ovarium, in such cases, is frequently abortive, and the seeds, when prolific, are generally much fewer than where the flowers are single. . Some curious experiments recently made on the productt~n of blue instead of red flowers in the Hydrangea hortens1s, illustrate the immediate effect of certain soils on the colours of the petals. In garden-mould or compost, the flowers are invariably red; in some kinds of bog-earth they are blue; and the same change is always produced by a particular sort of yellow loam. . Linnreus was of opinion that the primrose, oxlip, cowslip, and polyanthus, were only vadeties of the same species. The majority of modern botanists, on the contrary, consider them to be distinct, although some conceived that the oxlip might be a cross between the cowslip and the primrose. Mr. Her· bert has lately recorded the following experiment:-" I raised from the natural seed of one umbel of a highly-manured red cowslip, a primrose, a cowslip, oxlips of the usual and other colours, a black polyanthus, a hose-in-hose cowslip, and a na· tural primro e bearing its flower on a polyanthus stalk. From the seed of that very hose-in-hose cowslip I have since raised a hose-in-hose primrose. I therefore consider all these to be only local varieties depending upon soil and situation*." Pro· • Hort. Trans., vol. iv., p. 19. Ch.II.] PRODUCED BY HORTICULTURE. 35 fessor Henslow, of Cambridge, has since confirmed this experiment of Mr. Herbert, so that we have an example, not only of the remarkable varieties which the florist can obtain from a common stock, but of the distinctness of analogous races found in a wild state *. On what particular ingredient, or quality in the earth, these changes depend, has not yet been ascertained t. But gardeners are well aware that particular plants, when placed under the influence of certain circumstances, are changed in various ways according to the species; and as often as the experiments are repeated similar results are obtained. The nature of these results, however, depends upon the species, and they are, therefore, part of the specific character ; they exhibit the same phenomena again and again, and indicate certain fixed and invariable relations between the physiological peculiarities of the plant, and the influence of certain external agents. They afford no ground for questioning the instability of species_, but rather the contrary ; they present us with a class of phenomena which, when they are more thoroughly understood, may afford some of the best tests for identifying species, and proving that the attributes originally conferred, endure so long as any issue of the original stock remains upon the earth. * London's Mag. of Nat. Hist., Sept. 1830, vol. iii., p. 408. t Hort. Trans., vol. iii., p. 173. 1>2 |
