8 
C. L. Herrick 
closely with thermic sensations. If a small area of the skin is isolated it 
is found that tickling with a feather is interpretated 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 differ- 
ences break down. It may be noted that general changes in tempera- 
tures 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 peculiarity of pain and the intense gratification of sense which 
adapt them to become sources of feeling, is their diffusive (irradiative) 
character. If the current suggestion that algesic stimuli pass by con- 
duction through the gray matter of the cord be substantiated, a much 
closer connection with the visceral centers than hitherto suggested may 
be postulated, and the thrill of pain can be readily interpreted as the 
sympathetic contraction wave passing throughout the vascular system. 
The evidence for the existence of adequate vaso-motor causes of the sen- 
sational 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 disturbances. . . . Flushes of 
cold and heat; tingling and palpations local and general; gusts and tor- 
rents in the blood; creeping, swelling, scintillation of the skin; giddi- 
ness and elation — ^these and indescribable ^all-over ^ sensations are easily 
separable from the intellectual appreciation, which may even be absent; 
and one may be a wondering spectator observing the irrational gyrations 
of his own sense to tintinnabulating stimuli upon which judgment turns 
the cold shoulder. Another class, afforded by the tickling and shudder- 
ing or irradiating sensations proper, further illustrate the necessity of 
diffusion in emotional sensation. The slight sensations of tickling, aided 
by subjective modifications, extend in most varied and irresistible sen- 
sations over the whole body. Its emotional character is almost wholly 
apart from the intellectual element. The shudder and chill which spring 
from a gritting sound or the velvety touch of a peach, imply in addition 
considerable instinctive elements.”^ 
The mechanism of the process of irradiation has been investi- 
gated by Professor Herrick (following Dogiel) in the case of 
certain vascular epithelia (especially in the sexual organs) whose 
excitation is connected with some of the most intense pleasurable 
experiences/ Association tracts in the cortex illustrate the mech- 
anism of irradiation in the case of the higher affective processes 
where the revival of residua plays an important part. 
® Reference Handbook^ pp. 270-272. 
See references in Baldwin's Dictionary of Philosophy and Psychology, article 
“Irradiation^^ and cf. Journal of Comparative Neurology , vol. 7, p. 155 (March, 1898); 
vol. 2, 1892, pp. 111-114; vol. 5, 1895, pp. 1-32. For an illustration of the type of 
diffuse peripheral nerve plexus here referred to, see Herrick and Coghill, Journal of 
Comparative Neurology, vol. 7, p. 32-53 (July, 1898). 
