26 Journal of Comparative Neurology. 



fourth, representations which awaken by association either re- 

 produced pains and gratifications which, in turn, give rise to 

 total sensations, or the latter without the former ; fifth, instincts, 

 which obey laws of association whose rational explanation lies 

 in the development or phylogenetic history. 



Pain and sense gratification are more difficult to construe, 

 because more direct and simple than the others named. So 

 long as pain, etc., were regarded as simply exaggerated forms 

 of ordinary sensation the problem was insoluble. That this is 

 not the case is suggested by the fact that they pursue other 

 courses in the cord, and are associated more closely with ther- 

 mic sensations. If a small area of the skin is isolated it is 

 found that tickling with a feather is interpreted as warmth, and 

 a thrust with a needle cannot be distinguished from heat. In 

 other words, if the local signs by which position is recognized 

 are excluded, the differences break down. It may be noted 

 that general changes in temperature states are closely connected 

 with the general feelings, as witness a shudder or the cold chills 

 of fear, and the glow of pleasure. Briefly stated, the peculiar- 

 ity of pain and intense gratification of sense which adapt them 

 to become sources of feeling, is their diffusive (irradiative) char- 

 acter. If the current suggestion that algesic stimuli pass by 

 conduction through the gray matter of the cord be substantiated, 

 a much closer connection with the visceral centres than hitherto 

 suggested may be postulated, and the thrill of pain can be read- 

 ily interpreted as the sympathetic contraction wave passing 

 throughout the vascular system. The evidence for the exist- 

 ence of adequate vaso-motor causes of the sensational element 

 in emotion is largely subjective, but those familiar with nervous 

 diseases will not lack for evidence that variations in circulation 

 are powerful factors in emotional disturbance. Shame is an 

 emotion quite independent at times from any judgment of ade- 

 quate occasion for chagrin. It is very closely connected with 

 peripheral vascular changes. In anaemic or neurotic persons 

 the flush may come without any external exciting cause, and 

 yet frequently produces all the subjective effects of shame. Not 

 very infrequently this symptom becomes intolerable and almost 



