286 
Gravity requires little explanation. That, in the absence 
of other influences, hair would tend downwards, on account of 
the ever-present force of gravity is obvious; but, as hair is a 
light substance, the pull of gravity would not be strong, except 
in the case of long hair. The influence of surrounding media 
must be considered under two headings :— 
1.—The direction either through air or water which the 
animal usually takes. 
2.—The direction which air or water takes with regard to 
the animal. 
It is obvious that an animal moving head-first through air 
or water would have its hair arranged to point backwards. 
Whether the hair always retained this direction would depend 
on the constancy of the motion and the potency of conflicting 
influences. The direction of the hair on a rabbit plainly 
accords with its motion through the air—even the hair on the 
ears grows towards the tips. 
Under the second heading, if an animal were to be 
“stationary and retain the same position, at any rate frequently, 
with regard to the direction of wind, or the flow of water, its 
hair would obviously become directed the way of the wind or 
water. But the influence of rain must also be reckoned as flow 
of water, and, as rain flows off an animal in accordance with 
gravity, it is obvious that the assistance of rain will tend to 
point the hair in the same direction as gravity tends to 
pull it. 
Roughly-speaking, then, rain and gravity pull the hair — 
perpendicularly ; while motion through the air tends to arrange 
the hair horizontally. If one set of forces be in the ascendant 
the hair will assume a position in accordance ; but if the forces 
are nearly equal the hair would assume a curve, either hori- 
zontal-perpendicular, or perpendicular-horizontal, according to 
conditions. 
Muscular action can overcome other influences, and give 
to the hair, say, an upright position, as in the familiar instance 
of an angry cat, or the human being under influence of fright. 
But it would require a great amount of force to be expended to 
