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Show 444 DARWINISM OllAP. X[V The same remark applies to the views of Professor Geddes on the laws of O'rowth which have determined certain essential features in ~he morphology of plants and animals. The attempt to substitute these hws for those of variation and natural selection has failed in ca cs where we can apply n, definite te. t, as in that of the origin of spines on trees and shrubs ; while the extreme diversity of vegetable structure and form among the plants of the same country and of the same natural order, of itself affords a proof of the preponderatin()' influence of variation and natural selection in keeping the ~nany diverse forms in harmony with the highly complex and ever-changing environment. Lastly, we have seen that Professor \Yeismann's theory of the continuity of the germ-plasm and the consequent nonheredity of acquired chamcters, while in perfect harmony with all the well-ascertained facts of heredity and development, acids greatly to the importance of natural selection as the one in variable and ever-present factor in all organic change, and tha.t which can alone have produced the temporary fixi ty combined with the secular modification of species. vYhile aclmittino·, as Dn.rwin always admitted, the co-operation of the fundamental laws of growth and variation, of correlation and heredity, in determining the direction of lines of variation or in the initiation of peculiar orga.ns, we find that variation and natural selection are ever-present agencies, which take possession, as it were, of every minute change originn.tc(l by these fundamental causes, check or favour their furth <'l' development, or modify them in countless varied w:1 ys accordin()' to the varying needs of the organism. \\Tha.tc-vcr other ca~scs have been at work, Natura1 Selection is supl'l'llll', to an extent which even Darwin himself hesitated to <:him for it. The more we study it the more we arc convin eel of its overpowering import:mce, and th' more confidently we chim, in Darwin', own words, that it "has been the most import:wt, but not the exclusive, means of modification." CHAPTER XV DARWINISM APPLIED 'l'O MAN General identity of human and animal structure-Rudiments and variations showing relation of man to other mammals-The embryonic development of man and other mammalia-Diseases common to man and the lower animals- The animals most nearly allied to manTho brains of man aml apes-Extemal differences of man and apesSummary of the animal characteristics of man - Tho geological antiquity of man-Tho probable birthplace of man- The origin of the moral and intellectual nature of man-The argument from continuity-The origin of the mathematical faculty-The origin of the musical and artistic faculties- Indepemlent proof that these faculties have not been developed by natural selection-The interpretation of the facts-Concluding remarks. OuR review of modern Darwini m might fitly have terminated with the preceding chapter; but the immense interest that attaches to the origin of the human race, and the amount of misconception which prevails regarding the essential teachings of Darwin's theory on this question, as well as regarding my own special views upon it, induce me to devote a final chapter to its discussion. To any one who considers the structure of man's body, even in the most superficial manner, it must be evident that it is the body of an animal, differing greatly, it is true, from the bodies of all other animals, but agreeing with them in all essential features. The bony structure of man classes him as a vertebrate; the mode of suckling his young clar;ses him as a mammal; his blood, his muscles, and his nerves, the structure of his heart with its veins and arteries, his lungs and his whole respiratory and circulatory systems, all clo. ely corre pond to those of other mammals, and are often almost identical with |