Chap. IV. IX ANIMALS. 101 



hairs, feathers, &c. By the contraction of these muscles 

 the hairs can be instantly erected, as we see in a dog, 

 being at the same time drawn a little out of their sockets; 

 they are afterwards quickly depressed. The vast num- 

 ber 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 vibrissas of cer- 

 tain quadrupeds. The arrectores pili contract not only 

 under the above emotions, but from the application of 

 cold to the surface. I remember that mv mules and dogs, 

 brought from a lower and warmer country, after spend- 

 ing 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-shin during the chill 

 before a fever-fit. Mr. Lister has also found, 19 that tick- 

 ling a neighbouring part of the skin causes the erection 

 and protrusion of the hairs. 



From these facts it is manifest that the erection of 

 the dermal appendages is a reflex action, independent 

 of the will; and this action must be looked at, when, 

 occurring under the influence of anger or fear, not as a 

 power acquired for the sake of some advantage, but 

 as an incidental result, at least to a large extent, of the 

 sensorium being affected. The result, in as far as it is 



18 ' Lehrbueh der Histolog-ie des Menschen,' 1857, s. 

 82. I owe to Prof. W. Turner's kindness an extract from 

 this work. 



19 ' Quarterly Journal of Microscopical Science,' 1853, 

 vol. i. p. 262. 



