whole arterial system is dilated, with consequent blushing from this effect on the dermal capillaries of the face, neck, scalp and hands, and sometimes more extensively even; from the same cause the eyes slightly bulge.  The whole glandular system likewise is stimulated, causing the secretions,—­gastric, salivary, lachrymal, sudoral, mammary, genital, etc.—­to be increased, with the resulting rise of temperature and increase in the katobolism generally.  Volubility is almost regularly increased, and is, indeed, one of the most sensitive and constant of the correlations in emotional delight....  Pleasantness is correlated in living organisms by vascular, muscular and glandular extension or expansion, both literal and figurative.” (G.  Dearborn, “The Emotion of Joy,” Psychological Review Monograph Supplements, vol. ii, No. 5, p. 62.) All these signs of joy appear to occur at some stage of the process of sexual excitement.

In some monkeys it would seem that the muscular movement which in man has become the smile is the characteristic facial expression of sexual tumescence or courtship.  Discussing the facial expression of pleasure in children, S.S.  Buckman has the following remarks:  “There is one point in such expression which has not received due consideration, namely, the raising of lumps of flesh each side of the nose as an indication of pleasure.  Accompanying this may be seen small furrows, both in children and adults, running from the eyes somewhat obliquely towards the nose.  What these characters indicate may be learned from the male mandril, whose face, particularly in the breeding season, shows colored fleshy prominences each side of the nose, with conspicuous furrows and ridges.  In the male mandril these characters have been developed because, being an unmistakable sign of sexual ardor, they gave the female particular evidence of sexual feelings.  Thus such characters would come to be recognized as habitually symptomatic of pleasurable feelings.  Finding similar features in human beings, and particularly in children, though not developed in the same degree, we may assume that in our monkey-like ancestors facial characters similar to those of the mandril were developed, though to a less extent, and that they were symptomatic of pleasure, because connected with the period of courtship.  Then they became conventionalized as pleasurable symptoms.” (S.S.  Buckmann, “Human Babies:  What They Teach,” Nature, July 5, 1900.) If this view is accepted, it may be said that the smile, having in man become a generalized sign of amiability, has no longer any special sexual significance.  It is true that a faint and involuntary smile is often associated with the later stages of tumescence, but this is usually lost during detumescence, and may even give place to an expression of ferocity.

When we have realized how profound is the organic convulsion involved by the process of detumescence, and how great the general motor excitement involved,