CHAP. II. 



CONSIDERED BOTANlCALLY. 



215 



The subject of species and varieties has, in our opinion, been placed in the 

 clearest light, by Professor De Candolie, in his Theorie E' lementaire, and in 

 his Pliysiologie Vegeiale. In the latter work, this celebrated botanist recog- 

 nises in plants — species, races, varieties, and variations. 



Species. — Under the name of species, that is what we consider aboriginal 

 species in contradistinction to the botanical species of botanists, Professor 

 De Candolie unites all those individuals which bear a sufficient degree of re- 

 semblance to each other, to induce us to believe that they might have origi- 

 nated in one being, or one pair of beings. The degree of resemblance 

 which authorises us to unite individuals under the denomination of a species 

 varies much in diiTerent families ; and it often happens that two individuals 

 which really belong to the same species differ more between themselves in 

 appearance, than others which are of distinct species : thus, the spaniel and 

 the Danish dog are externally more different from each other than the dog 

 and the wolf are ; and many of the varieties of our fruit trees offer more ap- 

 parent differences than are found between many species. {Physiol. Veget., 

 vol. ii. p. 689.) 



If all the alleged species and varieties of any tree, shrub, or plant were 

 collected together, and cultivated in the same garden, however numerous 

 were the varieties, and however remote they might appear to be from the 

 original species, it would be practicable, after a series of years, to decide 

 with absolute certainty what were aboriginal or fixed features, and what 

 features were variable. For example, in the case of the apple, notwath- 

 standing the thousands of varieties in cultivation throughout the temperate 

 regions of the world, and the immense difference between some of the varie- 

 ties (for example, the Alexander or the Hawthornden and the original 

 crab), and even the great difference between the crabs of different parts of 

 Europe, yet in no case is there any danger of one of these varieties being 

 mistaken for a pear. One general character of leaf, flower, and fruit is 

 common to the whole of them, though it may not be easy to define in what 

 this essential character consists, in such a manner as to render it observable to 

 any one who had not seen a great number of varieties of apples and crabs. 

 Again, in the case of the common hawthorn, though some of the varieties 

 have deep red fruit, others pale red fruit, others yellow, and others black 

 fruit j and though some varieties of hawthorn have drooping branches, and 

 others have them rigidly erect and fastigiate ; though some have the leaves 

 finely cut, and others obtusely lobed or scarcely lobed at all; though some 

 are polygynous, and some are monogynous ; yet there never can be any 

 difficulty, when all these varieties are before us, in determining that they 

 belong to one and the same species. The same oloservation will apply to the 

 numerous varieties of the cockspur thorn, which now figure in our catalogues 

 as distinct species; and we think that it might be apphed to many varieties 

 of the genera i^-axinus, L^'lraus, *S'alix, Quercus, Pinus, and to various others. 

 Could v/e bring before us, into one plantation, all those ashes which are 

 natives of America, and watch them for a sufficient number of years, we have 

 no doubt that we should not find it more difficult to assign them to one 

 species, than we do the different vai'ieties of the European ash to the i^raxinus 

 excelsior. All the elms of Europe, we are inclined to be of opinion, may 

 be reduced to only three species ; and we much question if, on De Can- 

 dolle's principle of determining what a species is, there would be more than 

 a tithe of the names which are ranked as such under iSalix, Quercus, &c. 



Races.- — A race in the vegetable, as in the animal, kingdom, De Candolie 

 observes, " is such a modification of the species, whether produced by exterior 

 causes, or by cross fecundation, as can be transmitted from one generation to 

 another by seed." Thus, among all the cultivated vegetables and fruits, both 

 of the garden and ofthe field, the greater number of sorts may be considered as 

 races, because they may all be continued by seed ; the culture given and other 

 circumstances being the same. If the culture were neglected for a series of 

 generations, there can be no doubt that the race would revert to the abori- 



