352 UNIVERSITY OF COLORADO STUDIES 



somewhat differently because, according to the testimony of com- 

 parative anatomists^'^ they lack the necessary facial muscles for 

 language and the smile. 



The laugh may have another physiological raimn d'etre besides 

 that mentioned by Darwin, Spencer and Sully, of relief of cerebral 

 distension and congestion. Like singing, it may be a therapeutic 

 agency in reference to pulmonary exercise, blood -oxygenation and 

 general bodily nutrition. The deep inspirations which the singer 

 and laugher are compelled to make cause a distension of a number 

 of airvessels ordinarily in a condition of semi- or almost complete 

 collapse. As a result of the laugh the circulation is hurried on 

 through them and the lungs are developed to their fullest capacity. 

 The well-developed lungs, by facilitating the process of oxygenation, 

 favor the nutrition of the body in general. The laugh, it is true, 

 causes 'a cessation of cerebal strain,' but the greatest, relief is of 

 pulmonary or vaso-motor origin. The sigh also possesses the same 

 function, but the difference between the sigh and the laugh is the 

 difference between work and play. As a general rule the play activ- 

 ities are more general and involve a greater amount of metabolism. 

 The vitality of play is more intense. As singing has been recom- 

 mended as a valuable adjunct in the treatment of anaemia and pithi- 

 noid chests, so laughter must not be denied its therapeutic and 

 metabolic virtues. Deep inspirations favor the flow of blood through 

 the lungs, from the right to the left side of the heart. Thus occa- 

 sional sighs or laughs, or in other words deep inspirations, interrupt 

 the shallow breathing constituting so-called 'breathless attention.' 

 The shallow breathing leads to stagnation of blood in the right heart, 

 and an occasional deep inspiration is necessary to relieve this. By 

 holding the breath for a moment the stagnation of the blood in the 

 right heart will provoke epigastric pulsation and cause the veins in the 

 head and neck to swell. In cases of death from suffication or drown- 

 ing, the right heart is found engorged with blood. Now in most 

 instances of witticism or in joking, although not in all, there is an 

 element of expectation, suspense or inhibited function. The laugh 



(>) Cited by A. H. Keaiie. 'Etbnoloey.' 



