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Show 128 THE DESCENT OF 1\IAN. these it serves exclusively to aid the male m the act of reproduction. Mr. J. Wood, in his valuable series of papers/' has minutely described a vast number of muscular variations in man, which resemble normal structures in the lower animals. Looking only to the muscles which closely resemble those regularly present in our nearest allies, the Quadrumana, they are too numerous to be here even specified. In a single male subject, having a strong bodily frame and well-formed skull, no less than seven muscular variations were observed, all of which plainly represented muscles proper to Yarious kinds of apes. This man, for instance, had on both sides of his neck a true and powerful "levator claviculw," such as is found in all kinds of apes, and which is said to occur in about one out of sixty human subjects. 46 Again, this man had "a special abductor of "the metatarsal bone of the fifth digit, such as Pro" fessor Huxley and Mr. Flower have shewn to exist "uniformly in the higher and lower apes." ~rhe hands and arms of man are eminently characteristic structures, but their muscles are extremely liable to vary, so as to resemble the corresponding muscles in the lower animals. 47 Such resemblances are either complete and per- 45 These papers deserve careful siuLly by any one who desires to learn how frequently our muscles vary, and in varying como to resemble those of the Quadrumuna. The following references relate to the few points touched on in my text : vol. xiv. 18G5, p. 379-384; vol. xv. 1866, p. 24:1, 24:2; vol. xv. 1867, p. 5H; vol. xvi. 1868, p. 524. I may here add that Dr. Mmie and Mr. St. George J\1ivart have shewn in their Memoir on the Lemuroidca. (''Transact. Zoolog. Soc.' vol. vii. 18G9, p. 9G), how extraordinarily v:niablc some of tho muscles arc in these animals, the lowest members of the l'rimates. Gradations, also, in tl\e muscles leading to structures foun<l in animals still lower in the scale, are numerous in the Lcmuroiuea. 46 Prof. J\'Iacalister in' Proc. R. Irish Academy,' vol. x. 18G8, p. 124. 47 Prof. l\facalister (ibid. p. 121) has tabulated his observations, and finds that muscular abnormalities are most frequent in the forearms, secondly in the face, thirdly in the foot, &c. CHAP. IV. MANNER OF DEVELOPMENT. 120 feet or imperfect, yet in this latter case manifestly of a transitional nature. Certain variations are more common in man, and others in woman, without our being able to assign any reason. Mr. Wood, after describing numerous cases, makes the following pregnant remark : " Notable departures from the ordinary type of the " muscular structures run in grooves or directions, which "must be taken to indicate some unknown factor, of "much importance to a comprehensive knowledge of " general and scientific anatomy." 48 That this unknown factor is reversion to a former state of existence may be admitted as in the highest degree probable. It is quite incredible that a man should through mere accident abnormally resemble, in no less than seven of his muscles, certain apes, if there had been no genetic connection between them. On the other hand, if man is descended from some ape-like creature, no valid reason can be assigned why certain muscles should not suddenly reappear after an interval of many thousand generations, in the same manner as with horses, asses, and mules, dark-coloured stripes suddenly reappear on the legs and shoulders, after an interval of hundreds, or more probably thousands, of generations. These various cases of reversion are so closely related 48 The Rev. Dr. Haughton, after giving (' Proc. R. Irish Academy,' June 27, 1864:, p. 715) a remarkable case of variation in the human flexor pollicis longus, adds, " This remarkable example shews that man " may sometimes possess the arrangement of tendons of thumb and " fingers characteristic of the macaque; but whether such a case should "be regarded as a macaque passing upwards into a man, or a man " passing downwards into a macaque, or as a congenital freak of " nature, I canuot undertake to say." It is satisfactory to hear so capable an anatomist, and so embittered an opponent of evolutionism, admitting even the possibility of either of his first propositions. Prof. Macalister has also described (' Proc. R. Irish A cad.' vol. x. 1864, p. 138) variations in the flexor pollicis longus, remarkable from their relations to the same muscle in the Quadrumana. VOL. L K |