236 BIOLOGY AND HUMAN LIFE 



passages is that of having the affected area spread into the 

 sinuses (the bone spaces of the skull), which are connected 

 with the nostrils. The snuffing of a salt solution (a teaspoonful 

 of salt to a pint of water) or the use of antiseptics, such as 

 argyrol, is often helpful ; but it is better in all cases to get the 

 advice of a physician than to take any chances with these 

 organs. 



195. Hygiene of the ear. The best care to give the ear is to 

 let it alone most of the time. When the secretion of wax in the 

 ear tube needs to be removed, the corner of a clean handker- 

 chief, twisted stiff, will serve. If an excessive accumulation 

 threatens to interfere with hearing, let the physician look after 

 it. The lining of the tube is too easily scratched, and the drum 

 is too easily broken, to allow unskilled hands to get at them. 

 Of course nothing should be put into the tube. If an infant gets 

 a button or a pea into it, have a skilled person remove the in- 

 truder. The danger of ordinary children's diseases, such as 

 measles, scarlet fever, and whooping cough, includes that of 

 infection of the inner ear by way of the Eustachian tube, which 

 connects the inner ear with the pharynx (see e, Fig. 115). There 

 is the further danger that the infection will spread into the 

 mastoid bone (the thick but spongy bone just back of the ear), 

 and through this to the brain. Such infection is often fatal. 

 The outer ear needs merely to be kept clean on every surface. 



196. Hygiene of the eye. The eye of the higher mammals is 

 distinctly a distance receptor, that is, an organ adapted to re- 

 ceiving impressions or stimuli from distant objects. But most 

 people in civilized communities use their eyes chiefly for seeing 

 objects or small markings at close range. The strain on the 

 muscles that adjust the lens for far and near vision (focusing) 

 often leads to headaches and irritability or nervousness. In 

 most cases the person who suffers does not know what ails him. 

 This kind of strain should be avoided by frequently looking 

 away from the work, gazing out of the window for a few mo- 

 ments at a time, or even closing the eyes. In many cases there 

 are imperfections in the lens of the eye or in the distance of the 



