PERSONAL APPEARANCES IN HEALTH AND DISEASE. 85 



plication of a mustard poultice, and carried further still, 

 the first effect of a % blister is to cause reddening of the 

 skin, and later as the blister rises exudation of fluid 

 from the blood in the dilated vessels of the cutis. In 

 speaking of pigmentation of the skin due to the effect 

 of heat, we said that the first effect was an increase in 

 the flow of blood, and no doubt it is due to this that 

 there comes to be increased formation of pigment. For 

 a brown stain is often long left after the application of 

 mustard or a blister, or after the skin has been inflamed 

 for some time. 



We are now in a position to explain the phenomena 

 of blushing and of pallor of the surface from fright. In 

 blushing, which is always most marked in thin-skinned, 

 fair people, and which is by no means limited to the 

 face, but may extend over the neck, shoulders, and 

 chest, the arteries are temporarily dilated. The sense of 

 shame acts through the medium of the brain in an 

 involuntary manner, and there is a temporary arrest of 

 the function of the nerves going to the blood-vessels. 

 The blood seems to " rush " to the cheeks, and the 

 individual feels hot and uncomfortable, whilst to the 

 observer the rosy flush will be seen mantling the cheeks, 

 ears, and forehead, and reaching to the roots of the hair. 

 The heart beats quicker, and the whole circulation is 

 temporarily excited. Then as the emotion sinks, the 



