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Show ~ONCLUSION. CHAP. XIV. others; it follows, that the amount of organic change in the fossils of consecutive formations probably serves as a fair measure of the lapse of actual time. A number of species, however, keeping in a body might remain for a long period unchanged, whilst within 'this same period, several of these species, by migrating into new countries and coming into competition with foreign associates, might become modified; so that we must not overrate the accuracy of organic change as a measure of tiine. During early periods of the earth's history, when the forms of life were probably fewer and simpler, the rate of change was probably slower; and at the first dawn of life, when very few forms of the simplest structure existed, the rate of change may have been slow in an extreme degree. The whole history of the world, as at present known, although of a length quite incomprehensible by us, will hereafter be recognised as a n1ere fragment of time, compared with the ages which have elapsed since the first creature, the progenitor of innumerable extinct and living descendants, was created. In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history. Authors of the highest eminence seem to be fully satisfied with the view that each species has been indopendently created. To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual. When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the CrrAP. XIV. CONCLUSION. 489 first bed of the Silurian system was deposited, they seem to me to be?ome ennobled. Judging from the past, we m~y. safely Infer that not one living species will transmit Its u~altered ~il~eness to a distant futurity. And of ,the spec~es now hving very few will transmit progeny of ~ny kind to a far distant futurity; for the manner in wluch all organic beings are grouped, shows that the grea~er number of species of each genus, and all the spemes of many genera, have left no descendants, but have become utterly extinct. We can so far take a prophetic glance into futurity as to foretel that it will be the common and. widely-spread species, belonging to the l~rger and dominant groups, which will ultimately prevail ~n~ procreate new and dominant species. As all the hvtng forms of life are the lineal descendants of those which l~ved long before the Silurian epoch, we ~ay feel certain that the ordinary succession by generation has never once been broken, and that no cataclysn1 h~s desolated the whole world. Hence we may look With s?me confidence to a secure future of equally inappreciable length. And as natural selection works solely by and for the good of each being, all corporeal and m~ntal endowments will tend to progress towards perfection. It is int~resting to contemplate an entangled bank, c~ot~ed with many plants of many kinds, with birds singin? on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms so different from each other, and dependent on each other in so c~mplex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction ; Inheritance which is almost implied by reproduction ; Variability from the indirect and direct action of the external con- Y3 |
