It must not be supposed that the resemblances between man and certain apes in the above and many other points--such as in having a naked forehead, long tresses on the head, etc.--are all necessarily the result of unbroken inheritance from a common progenitor, or of subsequent reversion. Many of these resemblances are more probably due to analogous variation, which follows, as I have elsewhere attempted to show, from co-descended organisms having a similar constitution, and having been acted on by like causes inducing similar modifications. With respect to the similar direction of the hair on the fore-arms of man and certain monkeys, as this character is common to almost all the anthropomorphous apes, it may probably be attributed to inheritance; but this is not certain, as some very distinct American monkeys are thus characterized. VARIABILITY OF MAN. [Descent of Man, page 26.] It is manifest that man is now subject to much variability. No two individuals of the same race are quite alike. We may compare millions of faces, and each will be distinct. There is an equally great amount of diversity in the proportions and dimensions of the various parts of the body, the length of the legs being one of the most variable points. Although in some quarters of the world an elongated skull, and in other quarters a short skull prevails, yet there is great diversity of shape even within the limits of the same race, as with the aborigines of America and South Australia--the latter a race “probably as pure and homogeneous in blood, customs, and language as any in existence”--and even with the inhabitants of so confined an area as the Sandwich Islands. An eminent dentist assures me that there is nearly as much diversity in the teeth as in the features. The chief arteries so frequently run in abnormal courses, that it has been found useful for surgical purposes to calculate from 1,040 corpses how often each course prevails. The muscles are eminently variable: thus those of the foot were found by Professor Turner not to be strictly alike in any two out of fifty bodies; and in some the deviations were considerable. He adds that the power of performing the appropriate movements must have been modified in accordance with the several deviations. Mr. J. Wood has recorded the occurrence of 295 muscular variations in thirty-six subjects, and in another set of the same number no less than 558 variations, those occurring on both sides of the body being only reckoned as one. In the last set, not one body out of the thirty-six was “found totally wanting in departures from the standard descriptions of the muscular system given in anatomical text-books.” A single body presented the extraordinary number of twenty-five distinct abnormalities. The same muscle sometimes varies in many ways: thus Professor Macalister describes no less than twenty distinct variations in the _palmaris accessorius_. CAUSES OF VARIABILITY IN DOMESTICATED MAN. [Descent of Man, page 28.]