378 ADVANCED PHYSIOLOGY 



(6 or 8 inches) or very far away, or if the image of the object 

 is blurred in any way whatever, a skilled oculist should be 

 consulted to remedy the defect. When reading book or paper 

 of average sized type, it should not be held nearer the eye than 

 sixteen inches; nor should the focussing muscles be obliged to 

 act for that distance for long periods without rest. To obtain 

 a change in the focussing requirement when reading, look 

 about the room or out of the window occasionally. 



Too intense light is apt to be used. It is only by actual 

 strain that the eye can function in our customary brilliant 

 illumination and if a glistening paper or picture is being 

 examined the result is all the worse. 



Ears. To preserve good hearing, nothing must interfere 

 with any portion of the hearing apparatus. No small object 

 should be allowed to touch the ear-drum, much less puncture 

 it. Ear "wax" should be removed with much care, and not 

 permitted to collect. 



The greatest danger to the ear lies in its relation, via the 

 Eustachian tube, to the throat. Inflammation of the pharynx 

 can thus spread to the middle ear, and cause pus formation 

 either there or in the nearby mastoid cells (page 364). It is 

 difficult to cure such a condition without endangering the 

 hearing function. 



Social Hygiene. By this term is meant the relation which 

 the mingling of people in numbers has upon the health of 

 each one, and of all collectively. In a general way, the 

 health of a community is the sum total of the health of its 

 individuals. 



Ever since the germ theory of disease was established by 

 Pasteur, it has been well known that the health of a home or 

 the health of a whole community may be determined by the 

 health or the sickness of a single individual. The process of 

 the transfer of a disease from one person to another is termed 

 a process of infection. 



Infection. Quite a contrast with the days of long ago, 



