OCR Text |
Show 420 CONCLUSION. [OHAP. XIV. present ; for differences, however slight, between any two forms, if not blinded by intermediate gradations, are looked at by most naturalists as sufficient to raise both forms to the rank of species. Hereafter we shall be compelled to acknowledge that the only distinction between species and well-marked varieties is, that the latter are known, or believed, to be connected at the present day by intermediate gradations, whereas species were formerly thus connected. Hence, without quite rejecting the consideration of the present existence of intermediate gradations between any two forms, we shall be led to weigh more carefully and to value higher the actual amount of difference between them. It is quite possible that forms now generally acknowledged to be merely varieties may hereafter be thought worthy of specific names, as with the primrose and cowslip ; and in this case scientific and common language will come into accordance. In short, we shall have to treat species in the same manner as those naturalists treat genera, who admit that genera are merely artificial c01nbinations made for convenience. This may not be a cheering prospect ; but we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species. The other and more general departments of natural history will rise greatly in interest. The terms used by naturalists of affinity, relationship, community of type, paternity, morphology, adaptive characters, rudimentary and abortive organs, &c., will cease to be Inetaphorical, and will have a plain signification. When we no longer look at an organic being as a savage looks at a ship, as at something wholly beyond his comprehensjon; when we regard every production of nature as one which has had a history ; when we contemplate every complex structure and instinct as the summing up of many contrivances, each useful to the possessor, nearly in the same way as when we look at any great mechanical invention as the summing up of the labour, the experience, the reason, and even the blunders of numerous workmen ; when we thus view each organic being, how far more interestin·g, I speak from experience, will tlie study of natural history become! CHJ.P. XIV.] CONCLUSION. 421 A grand and almost untrodden field of inquiry will be opened, on the causes and laws of variation on correlati? n of gr?wth, on the effects of use and disuse, on the duect action o~ external conditions, and so forth. The study of do~estic :productions will rise immensely in value. A new variety raised bl man will be a far more import~ nt and interesting. subJ.ect for study than one more speCies added to the Infinitude of already recorded species. Our classifications will come to be as far as they can be so made, genealogies; and will then truly give what ~ay ~e called the plan of c~eation. The rules for classifymgwill. no ~oubt become Simpler when we have a definite obJe?t In VIew. We posses~ no pedigrees or armorial b~armss; ~nd we have to. discover and trace the many divergmg hnes of descent m our natural genealogies by characters of any kind which have long been inherited. Rudimentary organs will speak infallibly with respect to the nature of long-lost structures. Species and groups of species, which are called aberrant, and which may fancifully be called living fossils, will aid us in forming a picture of the ancient forms of life. Embryology will reveal to us the structure, in some degree obscured, of the prototypes of each great class. When we can feel assured that all the individuals of the same species, and all the closely allied species of most genera, have within a not very remote perjod descended from one parent, and have migrated from some one birthplace; and when we better know the many means of migration, then, by the light which geology now throws, and will continue to throw, on former changes of climate and of the level of the land, we shall surely be enabled to trace in an admirable manner the former migrations of the inhabitants of the whole world. Even at present, by comparing the differences of the inhabitants of the sea on the opposite sides of a continent, and the nature of the various inhabitants of that continent in relation to their apparent means of immigration, some light can be thrown on ancient geography. The noble science of Geology loses glory from the extreme imperfection of the record. The crust of the earth |