THE EXPRESSION OF THE EMOTIONS. 



439 



energy produced by pleasure and enjoyment, passing on by an efflux 

 through the motor nerves to various classes of the muscles, finds a 

 vent in joyous merriment, dancing, clapping the hands, and, above all, 

 in emissions of sound and motions of the zygomatic muscles, which 

 draw the mouth backward and upward. From the manner in which 

 the upper teeth are exposed in laughter and broad smiling, Mr. Dar- 

 win cannot doubt that some of the muscles running to the upper lip 

 are likewise brought into moderate action. The upper and lower or- 

 bicular muscles of the eyes are at the same time more or less con- 

 tracted, while the contractile force exerted upon the vessels or glands 

 of the eye causes the same flow of tears in extreme laughter as in sor- 

 row. Both laughing and weeping are seen in a minor degree in many 

 of the lower animals. In children tears do not flow, Mr. Darwin as- 

 sures us, at the first, but are induced by the effect of prolonged scream- 

 ing, in gorging the vessels of the eye. This suffusion, leading at first 

 consciously, and at last habitually, to the contraction of the muscles 

 round the eyes, in order to protect or relieve them, the lachrymal 

 glands become affected through reflex action. Thus, although in the 



Fig. 2. 



The same ln a Humble and Affectionate Feame of MrsD. (By M. Riviere.) 



first instance a merely incidental result, as purposeless as the secretion 

 of tears from a blow outside the eye, or as a sneeze from bright light 

 affecting the retina, we may understand how the shedding of tears 

 serves as a natural relief to suffering." 



Mr. Darwin's work is profusely illustrated by woodcuts and pho- 

 tographs of the human face, and of the attitudes and expressions of 

 various animals. We give some of his figures, with his accompanying 

 descriptions, exemplifying the principle of antithesis in the dog and cat. 



