The vast number of these minute
muscles over the whole body of a hairy quadruped is astonishing.
The erection of the hair is, however, aided in some cases,
as with that on the head of a man, by the striped and voluntary
muscles of the underlying _panniculus carnosus_. It is by the action
of these latter muscles, that the hedgehog erects its spines.
It appears, also, from the researches of Leydig[18] and others,
that striped fibres extend from the panniculus to some of
the larger hairs, such as the vibrissae of certain quadrupeds.
The _arrectores pili_ contract not only under the above emotions,
but from the application of cold to the surface. I remember
that my mules and dogs, brought from a lower and warmer country,
after spending a night on the bleak Cordillera, had the hair
all over their bodies as erect as under the greatest terror.
We see the same action in our own _goose-skin_ during the chill
before a fever-fit. Mr. Lister has also found,[19] that tickling
a neighbouring part of the skin causes the erection and protrusion
of the hairs.
[15] _Melopsittacus undulatus_. See an account of its habits
by Gould, `Handbook of Birds of Australia,' 1865, vol.
Pages:
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159