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overcome the opposing influences permanently ; so when this is 
necessary extra secretion is brought into play, and the hair 
is made of sufficient stiffness in proportion to its length to stand 
the strain of a position contrary to incident forces. The 
so-called whiskers of the cat, rabbit, etc., are familiar 
examples: they are made of sufficient strength to withstand 
the pull of gravity, while the animal has the muscular power 
to turn them so that they may not impede its movements. 
In the same manner the ornamental arrangement of hair 
on the top and around the heads of certain monkeys must be 
sustained in its position contrary to the pull of gravity, and 
contrary to the flow of rain by the strength of the secretion. 
Lastly, to come to Heredity. The hair, having on account 
of the various forces by which its direction is controlled, assumed 
a definite lie with regard to the body, would retain that position 
by the force of heredity, even when the animal’s descendants 
had permanently acquired a different carriage of the body, 
which changed the relationship of the hair in with regard to 
incident forces. It is, however, plain that as the strength of 
heredity would be a diminishing quantity, while the strength 
of other forces would be constant or increasing, the hair would 
in time tend to assume a direction in accordance with the 
newer conditions to which it might be exposed. 
In Man the position of the hair would not be affected by 
any motion through air or water in a general way, nor, except 
in very savage nations, would it be influenced greatly by the 
flow of rain. On the other hand, in Man’s pre-human ancestors 
such forces must have acted upon the hair, and influenced its 
direction ; and such direction would have become hereditary. 
On Man’s head the hair grows, roughly-speaking, from the 
crown to the forehead, and from the crown to the nape of the 
neck. The latter is in the direction which would be expected ; 
but the former is, to a certain extent, opp»sed to gravity—at 
any rate, in regard to such hair as lies between the crown and 
the top of the skull. 
In a woman the hair is made to grow in one direction, 
namely, from the forehead to the neck; but this is not what 
