THE AUTONOMIC NERVOUS SYSTEM 125 



extend this discussion by including other instances of 

 vasomotor accommodation. A most interesting and sug- 

 gestive case is the reaction which accompanies sleep. 

 This and the reciprocal case of the reaction that comes 

 with fixation of attention may be left to be dealt with in 

 another chapter. 



Other Autonomic Functions. Besides regulating the 

 beat of the heart and the local blood-supply, the autonomic 

 fibers convey impulses to contractile structures not related 

 to the circulatory system. The government of the alimen- 

 tary canal is carried on by means of such paths. Here, 

 as with the heart, there is a resident automatic power in 

 the walls of the tube, and what the nervous system does 

 is to modify the intrinsic tendency to tonic, rhythmic, 

 and progressive (peristaltic) action. A long time ago, in 

 the present treatment, it was said that inhibitory rather 

 than excitatory influences are the rule in this department 

 of nervous control. It will be convenient to discuss the 

 extent of autonomic government of the digestive tract 

 when we come to the abnormalities observed in the 

 neurasthenic. Autonomic impulses to the bladder and 

 reproductive organs are apt to be excitatory, though here 

 again the double possibility of reinforcement and inhibi- 

 tion remains. 



A division of the autonomic system which is of minor 

 significance, but interesting because it is curious, is the 

 pilomotor part. Under this head we include the fibers 

 which go to the scattering development of plain muscle 

 found in the skin. The contractile elements so placed are 

 attached to hairs \vhich may be rudimentary and scarcely 

 noticeable. When the muscle-cells contract under nervous 

 influence, either erection of the hairs or the risings of the 

 skin known as "goose-flesh" may be caused. Occasions 

 on which the hair "stands on end" are apparently rare in 

 human experience, but they are common enough in the 

 life of the cat. This animal has an excellent pilomotor 

 system. 



Of more importance is glandular control. The auto- 



