Book I. CHANGES FROM IMPREGNATION. 251 



experiments on the apple tree were equal to his hopes. This was, indeed, his principal object, and no 

 means of obtaining a successful issue were left untried. The plants which were obtained in this case 

 were found to possess the good qualities of both of the varieties employed, uniting the greatest health 

 and luxuriance with the finest and best-flavoured fruit. 



1634. Improved varieties of every fruit and esculent plant may he obtained by means of artificial impreg- 

 nation, or crossing, as they were obtained in the cases already stated. Whence Knight thinks, that this 

 promiscuous impregnation of species has been intended by nature to take place, and that it does in fact 

 often take place, for the purpose of correcting such accidental varieties as arise from seed, and of con- 

 fining them within narrower limits. All which is thought to be countenanced from the consideration of 

 the variety of methods which nature employs to disperse the pollen, either by the elastic spring of the 

 anthers, the aid of the winds, or the instrumentality of insects. But although he admits the existence 

 of vegetable hybrids, that is, of varieties obtained from the intermixture of different species of the same 

 genus, yet he does not admit the existence of vegetable mule?, that is, of varieties obtained from the 

 intermixture of the species of dift'erent genera ; in attempting to obtain which he could never succeed, 

 in spite of all his efforts. Hence he suspects that where such varieties have been supposed to take place, 

 the former must have been mistaken for the latter. It may be said, indeed, that if the case exists in the 

 animal kingdom, why not in the vegetable kingdom ? tov/hich it is, perhaps, difficult to give a satisfactory 

 reply : but from the narrow limits within which this intercourse is in all cases circumscribed, it scarcely 

 seems to have been the intention of nature that it should succeed even among animals. Salisbury is of a 

 dift'erent opinion, and considers {Ho7-t. Trans., i. o6i.) that new species may be created both by bees and 

 by the agency of man ; and the recent experiments of Herbert, Sweet, and others, seem to confirm this 

 opinion. Sweet's experience leads him to conclude that the plants of all orders strictly natural may be 

 reciprocally impregnated with success, and he has already, in the nursery-gardens of Messrs. Colville, 

 produced many new Gerknia and 7fhodora.ceae. 



1635. A sitigular or anomalous effect of crossing, or extraneous impregnation, is the change sometimes 

 undergone by the seed or fruit which is produced by the blossom impregnated. These results are not 

 uniform, but they are of frequent occurrence, and have attracted notice from a very early period. John 

 Turner observes {Hort. Trans., v. 63.) that Theophrastus and Pliny {Theophrast. Hist. Plant, 1. ii. c. 4.; 

 Plinii Hist. Nat, 1. xvii. c. 25.) seem to allude to it, and that the notion was entertained by Bradley, who, 

 in his New Improvements in Planting and Gardening, after giving directions for fertilising the female 

 flowers of the hazel with the pollen of the male, says, " By this knowledge we may alter the property and 

 taste of any fruit, by impregnating the one with the farina of another of the same class, as, for example, 

 a codlin with a pearmain, which will occasion the codlin so impregnated to last a longer time than usual, 

 and be of a sharper taste ; or, if the winter fruit should be fecundated with the dust of the summer kinds, 

 th will decay before their usual time; audit is from this accidental coupling of the farina of one kind with 

 the other, that in an orchard, where there is a variety of apples, even the fruit gathered from the same tree 

 differs in its flavour and times of ripening ; and, moreover, the seeds of those apples so generated, being 

 changed by that means from their natural qualities, will produce different kinds of fruit, if they are sown." 

 Turner, after quoting several instances, and, among others, one from the Philosophical Transactions 

 " concerning the effect which the farina of the blossoms of different sorts of apples had on the fruit of 

 a neighbouring tree," states upwards of six cases of hybridised apples, that had come within his own 

 observation ; and concludes with the remark, that, if there does exist in fruits such a liability to change, 

 it will at once be evident to the intelligent cultivator how much care is requisite in growing melons, 

 cucumbers, &c., to secure their true characters, even without reference to saving seed for a future crop. 

 In the same volume of the Horticultural Transactions (p. 234.) an account is given of different-coloured 

 peas being produced in the same pod, by crossing the parent blossom. All these facts seem to contradict 

 the generally received opinion, that crossing only aflfects the next generation ; here it appears to affect 

 the embryo offspring ; and a gardener, who had no keeping apples in his orchard, might communicate that 

 quality in part to his summer fruit by borrowing the use of a neighbour's blossoms from a late variety. It 

 is probable, however, that such counter-impregnations do not take place readily j otherwise the produce 

 of a common orchard would be an ever-varying round of monstrosities. 



Sect. VIII. Changes consequent upon Impregnation. 



1636. The peculiar changes consequent upon inipregnatio7i, whether in the flowers or 

 fruit, may be considered as external and internal. 



1637. E.rternal changes. At the period of the impregnation of the ovary the flower has attained to its 

 ultimate state of perfection, and displayed its utmost beauty of colouring and richness of perfume. But as 

 it is now no longer wanted, so it is no longer provided for in the economy of vegetation. Its period of 

 decline has commenced ; as is indicated, first by the decay of the stamens, then of the petals, and then of 

 the calyx, which wither and shrink up, and finally detach themselves from the fruit altogether, except in 

 some particular cases in which one or otherof them becomes permanent and falls only with the fruit. I'he 

 stigma exhibits also similar symptoms of decay, and the style itself often perishes. The parts contiguous 

 to the flower, such as the bractes and floral leaves, are sometimes also affected ; and finally the whole 

 plant, at least in the case of annuals, begins to exhibit indications of decay. But while the flower withers 

 and falls, the ovary is advancing to perfection, swelling and augmenting in size, and receiving now all the 

 nutriment by which the decayed parts were formerly supported. Its colour begins to assume a deeper and 

 richer tinge ; its figure is also often altered, and new parts are even occasionally added, wings, crests, 

 prickles, hooks, bloom, down. The common receptacle of the fruit undergoes also similar changes, 

 becoming sometimes large and succulent, as in the fig and strawberry ; and sometimes juiceless and 

 indurated, as in compound flowers. 



1638. Internal changes. If the ovary is cut open as soon as it is first discoverable in the flower, it will 

 be found to be divisible into several distinct parts, exhibiting an apparatus of cells, valves, and membranes, 

 constituting the pericarp, and sometimes the external coats of the seed. Impregnation has no sooner 

 taken place than its influence begins to be visible; the umbilical cord, which was formerly short and dis- 

 tended, is in some cases converted into a long and slender thread. Sometimes the position of the seed is 

 altered. Before impregnation the seeds of Caryophyllus aromaticus and Metrosidferos gummifera are 

 horizontal ; after impregnation they become vertical. Before impregnation the MagnbbV? seeds are erect ; 

 after impregnation they become inverted and pendulous. The figure of the seed is often also altered in passing 

 from its young to its mature state ; changing from smooth to angular, from tapering to oval, from oval to 

 round, and from rountl to kidney-shaped. But all the seeds are not brought to maturity, of which the 

 rudiments may exist in the ovary. LagoeVia and Hasselquistw produce uniformly the rudiments of two 

 seeds, of which they mature but one. But the principal changes resulting from impregnation are operated 

 in the seed itself, which, though previously a homogeneous and gelatinous mass, is now converted into an 

 organised body, or embryo. Such are the phenomena, according to the description of Gaertner, accom- 

 panying or following the impregnation of all flowers producing seeds: exceptions occur where the fecun- 

 dation is spurious and incomplete; where the ovary swells, but exhibits no traces of perfect seed within, 

 as often happens in the vine and T^mus ; or where barren and fertile seeds are intermingled together in 

 the same ovary. This proceeds from some defect either in the quantity or quality of the pollen ; but rather 

 in the quality, as it is not always plants having the most pollen that produce the most seeds. The 

 two stamens of the OrchidejE fecundate 8000 seeds, and the five stamens of tobacco fecundate 900 : while 



