characteristic of man are extremely liable to vary, so as to resemble
the corresponding muscles in the lower animals. (52. Prof. Macalister
(ibid. p. 121) has tabulated his observations, and finds that muscular
abnormalities are most frequent in the fore-arms, secondly, in the
face, thirdly, in the foot, etc.) Such resemblances are either perfect
or imperfect; yet in the latter case they are 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 variations, 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. (53. 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 cannot 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
( Proceedings Royal Irish Academy, vol. x. 1864, p. 138) variations in
the flexor pollicis longus, remarkable from their relations to the same
muscle in the Quadrumana.)
That this unknown factor is reversion to a former state of existence
may be admitted as in the highest degree probable. (54. Since the first
edition of this book appeared, Mr. Wood has published another memoir in
the Philosophical Transactions, 1870, p. 83, on the varieties of the
muscles of the human neck, shoulder, and chest. He here shews how
extremely variable these muscles are, and how often and how closely the
variations resemble the normal muscles of the lower animals. He sums up
by remarking, It will be enough for my purpose if I have succeeded in
shewing the more important forms which, when occurring as varieties in
the human subject, tend to exhibit in a sufficiently marked manner what
may be considered as proofs and examples of the Darwinian principle of
reversion, or law of inheritance, in this department of anatomical
science. ) It is quite incredible that a man should through mere
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