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Show 118 HYPOTHESIS OF 'l'HE D:E:VELOPMENT OF under different conditions as to both air and light. On the contrary, we have see~ reason for supposing th:1t th.e proportion of carbonic acid gas (the element f~tal to a!li· mal life) was large:v at the time of the carboniferous formation than it afterwards became. We have also seen that astronomers regard the zodiacal ~ight as a residuum of matter, enveloping the sun, and which was proba~ly ~t one time denset· than it is now. Here we have the Indl· cations of causes for a progress in the purification of t.he atmosphere and in the diffusion of light during the earlier ages of the earth's history, with which the progress .of organic life may have been conformable. An accesswn to the proportion of oxygen, and the ~ffulge!lce of the c~ntral luminary, may have been the tn:mediate P.rompt~ng cause of all those advances from species to specie~ which we have seen, upon other grounds, to be necessarily supposed as having -taken place. And causes of the like nature may well be supp~sed to operat~ on other spheres ot being, as we~l a.s on this. I do not _Indeed present these ideas as furmshJng the true explanation of the progress of organic creation; they are merely thrown out as hints towards the formation of a just hypothesis, the completion of which i~ only to be looked for when some considerable advances shall have been made in the amount and character of our stock of know ledge. Early in this century, M. Lamarck, a _naturalist .of the highest character, sugge~ted an hypothes~s .of organic progress which deservedly Incurred much nd1cule, although it contained a glimmer of the truth. He surmised, and endeavored with a great deal of ingenuity, to prove, that one being advanced in the course of generations to another, in consequence merely of its experience of wants calling for the exercise of its faculties in a particular direction, by which exercise new developments of organi took place, ending in variations sufficient to constitute a new !:ipe'"bes. Th lS he thought that a bird would be (.:.·i-,en by necessity to seek its food in the water, and that, In its efforts to :,qwim, the outstretGhing of its claws would lead to the expc.nsion of the intermediate membranes, and it would thus become web-footed. Now it is possible that wants and the exercise of faculties have enh-!red in some manner into the production of the phenomena which we have been considering; but certainly not in the way 2uggesled by Lainarck, whose whole notion :"'6 obv i • THE VEGETABLE AND ANIMAL KINGDOMS. 119 ously so inadequate to account for the rise of the organic kingdoms, that we only can place it with pity among the follies of the wise. Had the laws of organic development oeen known in his time, his theory might have been of a more imposing kind. It is upon these that the present hypothesis is mainly founded. I take existing natural means, and show them to have been capable of producing all the existing organisms with the simple and ~asily conceivable aid of a higher generative law, which we perhaps still see operating upon a limited scale. I also go beyond the French philosopher to a very important point, the original Divine conception of all the forms of being which these natural laws were only instruments in working out and realizing. The actuality of such a con- 1 ception I hold to be strikingly demonstrated by the disco- ~ ' veries of Macleay, Vigors and Swainson, with respect to .-;J the affinities and analogies of animal (and by implication vegetable) organisms.* Such a regularity in the structure, as we may call it, of the class~fication of animals, as is shown in their systems, is totally irreconcilable with the idea of form going on to form merely as needs and v,rishes in the animals themselves dictated. Had such been the case, all would have been irregular, as things arbitrary necessarily are. But, lo, the whole plan of being is as symtnetrical as the plan of a house, or the laying out of an old-fashioned garden! This must needs have been devised and arrranged for beforehand! And what a preconception or forethought have we here ! Let us only for a moment consider how various. are the external phy-sical conditions in which anin1als live-climate, soil, temperature, land, water, air-the peculiarities of food, and the various ways in which it is to be sought; the pe-culiar circumstances in which the business of reproduc-tion and the care taking of the young are to be attended to-all these requil'ed to be taken into account, and thousands of animah were to be formed suitable in organization and mental cl lracter for the concerns they were to have with these var= )US conditions and circumstances-here a tooth fitted for crushing nuts ; there a claw fitted to serve as a hook for ;us pension; here to repress teeth and develop a bony net. work instead; there to arrange for a bronchial apparatu~, to last only for a certain brief time; and all these animals were to he schemed out, each as a part of ,.. These affinities and analogies are explaiued in the next chapter |