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Show RARITY OF IIYBRIDS AMONG [Ch. IV. h h f the species1 from sowed parallel rows, near to eac ot er, o . . which he desired to breed, and instead of mublatmg, after Kolreuter's fashion, the plants of one of the parent stocks, he ff h · thers The branches of merely washed the pollen o t eir an · · · h tly bent towards each the plants, m each row, were t en gen . h d ot er an m· t er t w·m e d , -0 that the wind and numerous msects :s • h d f m the flowers of one to those of the other as t ey passe ro . species carried the po1len and produced fecundation, The' same observer saw a good exemplification of the manner in which hybrids may be formed in a state of nature. Some wallflowers and pinks had been growing in a garden, in a dry sunny situation, and their stigmas had been ripened s~ as to be moist, and to absorb pollen with avidity, although the1r anthers were not yet developed. These stigmas became impregnated by pollen, blown from some other adjacent plants of the same species, but had they been of different species, and not too remote in their organization, mule races must have resulted. When, indeed, we consider how busily some insects have been shown to be engaged in conveying anther·dust from flower to flower, especially bees, flower-eating beetles, and the like, it seems a most enigmatical problem how it can happen, that promiscuous alliances between distinct species are not perpetually occurring. How continually do we observe the bees diligently employed in collecting the red and yellow powder by which the stamens of flowers are covered, loading it on their hind legs, and carrying it to their hive for the purpose of feeding their young I In thus providing for their own progeny, these insects assist materially the process of fructification*. Few of our readers n~ed be reminded, that the stamens in certain plants grow on different blossoms from the pistils, and unless the summit of the pistil he touched with the fertilizing dust, the fruit does not swell, nor the seed arrive at maturity. It is by the help of bees chiefly, that the development of the fruit of many such species • s~e Barton on tho Geography of Plants, p. 67, Ch.IV.] PLANTS IN A WILD STATE. 55 is secured, the powder which they have collected from the stamens being unconsciously left by them in visiting the pistils. How often, during the heat of a summer's day, do we see the males of direcious plants, such as the yew-tree, standing separate from the females, and sending off into the air, upon the slightest breath of wind, clouds of buoyant pollen I That the zephyr should so rarely intervene to fecundate the plants of one species with the anther-dust of others, seems almost to realize the converse of the miracle believed by the credulous herdsmen of the Lusitanian mares- Ore omnes versa~ in Zephyrum, stant rupibus altis, Exceptantque leves auras : et sa~pe sine ullis Conjugiis, vento gravida~, mirauile dictu *· But, in the first place, it appears that there is a natural aversion in plants, as well as in animals, to irregular sexual unions ; and in most of the successful experiments in the animal and vegetable world, some violence has been used, in order to procure impregnation. 'rhe stigma imbibes, slowly and reluctantly, the granules of the pollen of another species, even when h ~s abu~dantly cover~cl with it; and if it happen that, during this penod, ever so shght a quantity of the anther-dust of its own species alight upon it, this is instantly absorbed, and the effect of the foreign pollen destroyed. Besides, it does not often happen that the male and female organs of fructification in differe~t species, arrive at a state of maturity at precisely 'the same time. Even where such synchronism does prevail, so that a cross impregnation is effected, the chances are very numerous against the establishment of a hybrid race. If we consider the vegetable kingdom generally, it must be recollected, that even of the seeds which are well ripened, the greater part are either eaten by insects, birds, and other animals, or decay for want of room and opportunity to germinate. Unhealthy plants are the first which are cut off by causes prejudicial to the species, being usually stifled by more vigorous individuals of their own kind. If, therefore, the relative fecundity or • Georg. lib, iii. 273. |