The Descent of Man

ect manner on the masticatory muscles, and on
the bones to which they are attached. In infants,
long before birth, the skin on the soles of the
feet is thicker than on any other part of the
body; (28. Paget, 'Lectures on Surgical Pathology,'
vol. ii, 1853, p. 209.) and it can hardly be
doubted that this is due to the inherited effects
of pressure during a long series of generations.
It is familiar to every one that watchmakers and
engravers are liable to be short-sighted, whilst
men living much out of doors, and especially
savages, are generally long-sighted. (29. It is a
singular and unexpected fact that sailors are
inferior to landsmen in their mean distance of
distinct vision. Dr. B.A. Gould ('Sanitary Memoirs
of the War of the Rebellion,' 1869, p. 530),
has proved this to be the case; and he accounts
for it by the ordinary range of vision in sailors
being "restricted to the length of the vessel and
the height of the masts.") Short-sight and longsight
certainly tend to be inherited. (30. 'The