Chap. IV. IN + ANIMALS. 103 



Ley dig, 20 in a transitional condition; the fibres exhibit- 

 ing only indications of transverse striation. 



Another explanation seems possible. We may admit 

 that originally the arrectores pill were slightly acted on 

 in a direct manner, under the influence of rage and 

 terror, by the disturbance of the nervous system; as is 

 undoubtedly the case with our so-called goose-shin be- 

 fore a fever-fit. Animals have been repeatedly excited 

 by rage and terror during many generations; and con- 

 sequently the direct effects of the disturbed nervous 

 system on the dermal appendages will almost certainly 

 have been increased through habit and through the tend- 

 ency of nerve-force to pass readily along accustomed 

 channels. We shall find this view of the force of habit 

 strikingly confirmed in a future chapter, where it will 

 be shown that the hair of the insane is affected in an 

 extraordinary manner, owing to their repeated accesses 

 of fury and terror. As soon as with animals the power 

 of erection had thus been strengthened or increased, 

 thev must often have seen the hairs or feathers erected 

 in rival and enraged males, and the bulk of their bodies 

 thus increased. In this case it appears possible that they 

 might have wished to make themselves appear larger and 

 more terrible to their enemies, bv voluntarilv assuming 

 a threatening attitude and uttering harsh cries; such 

 attitudes and utterances after a time becoming through 

 habit instinctive. In this manner actions performed 

 bv the contraction of voluntarv muscles mi^ht have been 

 combined for the same special purpose with those ef- 

 fected by involuntary muscles. It is even possible that 

 animals, when excited and dimly conscious of some 

 change in the state of their hair, might act on it by re- 

 peated exertions of their attention and will; for we have 



20 ' Lekrbuch der Histologie,' 1S57, s. 82. 



