398 MUSCULAR ACTION 



every feeling and emotion has a different set of movements involving, 

 when strong enough, practically the whole body. In these complex sets 

 of movements the muscles of course play the chief part, whether in the 

 wall of an arteriole or of the gut, in the diaphragm, or in the face. Epi- 

 .thelium also takes part. Our present inquiry asks how these motor reac- 

 tions are coordinated and the principles, if there are any, underlying 

 the different sets of movements. The more psychic aspects of feeling 

 are discussed in the next chapter, so here we briefly glance only at the 

 "reactions" in so far as they are a muscular function. 



We have seen that the motor nervous apparatus works probably on 

 the reciprocating plan: when one muscle-group is caused to contract 

 its antagonist is correspondingly inhibited and relaxed. About the 

 hinge-joints are two opposed sets of muscles, the one flexor and the other 

 extensor in function. There are pronators and supinators, elevators 

 and depressors, adductors and abductors, sphincters or constrictors and 

 dilators, the members of each pair being opposed or opposite in action 

 to each other. Again, there is another sort of antagonism of a vascular 

 sort in the vaso-motor mechanism. When vaso-constriction occurs in a 

 more or less well-defined area of the body vaso-dilatation is brought about 

 to compensate in some other area. Finally we find, if we compare vari- 

 ous emotions, that there is antagonism in the degree of muscle-activity: 

 in grief, for example, we tend to use our muscles little, in joy and glad- 

 ness and pleasure much. 



These basal antagonisms in the action of the muscles have been studied 

 not a little in relation to emotions which involve them in some char- 

 acteristic ways. Mixed up with the theories of pleasure and of pain, for 

 example, is the degree of general activity: pain hinders metabolism 

 and activity, and pleasure furthers it. In general, however, the only 

 correspondence which can be made out between aspects of feeling and 

 emotion and these motor oppositions (besides that just mentioned) is 

 a general agreement between pleasant emotions and contraction of 

 extensor muscles and unpleasant emotions and the action of muscles 

 classed as flexors. To this rule even there are many exceptions, just as 

 some beneficial things have a bitter taste and many deadly poisons are 

 sweet. Some emotions lack more or less any tone of the pleasant or 

 unpleasant, yet have well-marked muscular reactions. It is possible 

 that some quality of the mental side of an emotion other than pleasant- 

 ness or unpleasantness determines the motor combination. It is even 

 possible that we may have finally to look to the intricacies of the nervous 

 "net" and to its connections with the elements of the muscle-fabric 

 in order to account for the motor aspects of emotions. Meanwhile there 

 is always before us for admiration this marvellous structure of muscle 

 and nerve and other tissuess whose parts and action-principles even 

 centuries of self-rewarding but tantalizing research may not exhaust. 



