THE AUTONOMIC NERVOUS SYSTEM 197 



described in the last paragraph. If we note, however, that the 

 conditions that arouse these reactions are such as call for a rallying 

 of the Body for flight or struggle we begin to see wherein the im- 

 portance of this mechanism lies. In general its effect on the Body 

 is a diversion of resources from the maintenance organs to those of 

 external adaptation, the latter making up the mechanism on which 

 the Body must depend for salvation in time of stress. The dilation 

 of the pupil may be supposed to enhance the sensitiveness of 

 vision. The dryness of the mouth signifies that energy ordinarily 

 employed in producing saliva is now set free for use elsewhere. The 

 erection of the hair, of no importance in man, is in many of 

 the lower animals an important part of the scheme of defense. 

 The pallor of the face is the result of the diversion of blood from the 

 skin, whence it can be spared, to the muscles and brain where it is 

 greatly needed. The acceleration of the heart results in a quick- 

 ened circulation of blood through the regions of heightened activity. 

 The inhibition of the digestive organs is another example, like the 

 cessation of salivary secretion, of the suspension of functions not 

 immediately essential, in order that all the Bodily energy shall be 

 available for the emergency. Numerous other reactions of the 

 thoracico-lumbar mechanism also contribute to the general plan of 

 defense. These we shall examine in due course. Here we need only 

 note that all of them tend toward increasing the efficiency of the 

 skeletal muscles and the central nervous system, which together 

 make up the emergency mechanism. 



The Relation of the Autonomic System to Emotional States. 

 In a previous paragraph (p. 189) the fact was noted that emotion in 

 general is accompanied by activity of the autonomic system. We 

 have just examined the basis for this relationship in those emotions 

 that are associated with the immediate need of self-preservation. 

 An interesting fact, and one of great practical importance, is that 

 the emotion of worry or anxiety, which is responsible for much of 

 the discomfort of life, has significance as a means of preparing 

 before hand for a time of trouble. We may describe it as an an- 

 ticipatory emotion. We bring about in our Bodies through worry 

 the characteristic reactions of the thoracico-lumbar autonomic 

 system. Unfortunately, these reactions, useful indeed when the 

 actual stress is at hand, are inimical to the carrying on of the 

 ordinary bodily processes, so that their occurrence in advance of 



