fairly be attributed to it, and when the saving to be effected by the
economy of growth would be very small (23. Some good criticisms on this
subject have been given by Messrs. Murie and Mivart, in Transact.
Zoological Society, 1869, vol. vii. p. 92.), are difficult to
understand. The final and complete suppression of a part, already
useless and much reduced in size, in which case neither compensation
nor economy can come into play, is perhaps intelligible by the aid of
the hypothesis of pangenesis. But as the whole subject of rudimentary
organs has been discussed and illustrated in my former works (24.
Variation of Animals and Plants under Domestication, vol. ii pp. 317
and 397. See also Origin of Species, 5th Edition p. 535.), I need
here say no more on this head.
Rudiments of various muscles have been observed in many parts of the
human body (25. For instance, M. Richard ( Annales des Sciences Nat.,
3rd series, Zoolog. 1852, tom. xviii. p. 13) describes and figures
rudiments of what he calls the muscle pedieux de la main, which he
says is sometimes infiniment petit. Another muscle, called le tibial
posterieur, is generally quite absent in the hand, but appears from
time to time in a more or less rudimentary condition.); and not a few
muscles, which are regularly present in some of the lower animals can
occasionally be detected in man in a greatly reduced condition. Every
one must have noticed the power which many animals, especially horses,
possess of moving or twitching their skin; and this is effected by the
panniculus carnosus. Remnants of this muscle in an efficient state are
found in various parts of our bodies; for instance, the muscle on the
forehead, by which the eyebrows are raised. The platysma myoides, which
is well developed on the neck, belongs to this system. Prof. Turner, of
Edinburgh, has occasionally detected, as he informs me, muscular
fasciculi in five different situations, namely in the axillae, near the
scapulae, etc., all of which must be referred to the system of the
panniculus. He has also shewn (26. Prof. W. Turner, Proceedings of the
Royal Society of Edinburgh, 1866-67, p. 65.) that the musculus
sternalis or sternalis brutorum, which is not an extension of the
rectus abdominalis, but is closely allied to the panniculus, occurred
in the proportion of about three per cent. in upwards of 600 bodies: he
adds, that this muscle affords an excellent illustration of the
statement that occasional and rudimentary structures are especially
liable to variation in arrangement.
20