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Show 16 THE DESCENT OF MAN. PART L carefully copied from two works of undoubted accu-racy. ll . After the foregoing statements made by such bl.gh authorities it would be superfluous on my part to g1ve a number ~f borrowed details, shewing that the embryo of man closely resembles that of other mammals. . It may, however, be added that tl:e human embryo likewise resembles in various pomts of structure certain low forms when adult. For instance, the heart at first exists as a simple pulsating vessel; the excreta are voided thr01wh a cloacal passage; and the os ~occyx projects lik~ a true tan,'' extending considerably " beyond the rudimentnry legs.".12 In the embryos ~f all air-breathincr vertebrate~, certam glands called the corpora vVolffiana, 0 correspond with and act like th.e kidn.eys of mature fishes. 13 Even at a later embryomc perwd, some striking resemblances between man and the lowet· animals may be observed. Bischoff says that the convolutions of the brain in a human fretus at the end of the seventh month reach about the same stage of development as in a baboon when adult.14 The great toe, as Prof. Owen remarks/5 "which forms the fulcrum when "stauding or walking, is perhaps the most characteristic 11 'rho human embryo (upper fig.) is from Eeker, 'leones Phys.,' 1851-1859, tab. xxx. fig. 2. This embryo was ten lines in len~t~, so that the drawin"' is much magnified. The embqo of the clog 1s from Bischoff, 'Entwleldungsgeschichte des Hunde-Eies,' 1845, .tab. xi. fig. 4:2 n. 'rhis drawing is five times magnified, the embryo bemg 25 days old. The internal viscera have been omitted, and the uterine appendao- es in both drawings removed. I was directed to these figures by Pr~f. Huxley, from whose work, 'Man's Pl~ce in Kature,' the ~cloa ~~f giving them was take~. Hackel has also giVen analogous drawmgs m his ' SchopfungsgeschJChtc.' . , . 12 Prof. Wyman in 'Proc. of American Acau. of Sc1ences, vol. 1>. lSGO, p. 17. 13 Owen 'Anatomy of Vertebrates,' vol. i. p. 533. H 'Die Grosshirmvindungen des Menschen,' l SGS, s. ~5. u 'Anatomy of Vertebrates,' vol. ii. p. 553. CH.AP.I. RUDIMENTS. 17 "' peculiarity in the human structure;" but in an embryo, about an inch in length, Prof. vVyman 16 found <l< that the great toe was shorter than the others, and, ·" instead of being parallel to them, projected at an ·" angle from the side of the foot, thus corresponding " with the permanent condition of this part in the "' quadrumana." I will conclude with a quotation from Huxley,17 who after asking, does man originate in a different way from a dog, bird, frog or fish? says, "the "'reply is not doubtful for a moment; without question, "the mode of origin and the early stages of the develop" ment of man are identical with those of the animals " immediately below him in the scale: without a doubt "' in these respects, he is fa.r neare1· to apes, than the apes " are to the dog." R~tdiments. -This subject, though not intrinsically more important than the two last, will for several reasons be here treated with more fullness.18 Not one of the higher animals can be named which does not bear some part in a rudimentary condition; and man forms no exception to the rule. Rudimentary organs must be distinguished from those that are nascent; though in some cases the distinction is not easy. The former are either absolutely useless, such as the mammre of male quadrupeds, or the incisor teeth of ruminants 1\·hich never cut through the gums; or they are of such slight service to their present possessors, that we cannot .suppose that they were developed under the conditions 16 'Proc. Soc. Nat. Hist.' Boston, 1863, vol. ix. p. 185. 17 'l\fan's Place in Nature,' p. 65. 18 I had written a rough copy of this chapter before reading a valu. able pape~, " Caratteri rudimentali in ordine all' origine del uomo" (' Annuano della Soc. d. Nat.,' Modena, 1867, p. 81), by G. Canestrini, to which paper I am considerably inuebted. Hiickell1as given admi~ bl~ discussions on this whole subject, under the title of Dysteleology, m h1s ' Generelle l\forphologie' and ' Schopfungsgeschichte.' VOL. I. C |