MAN. 



367 



colony. These demands of society gradually mould the 

 individuals and their social ideals. Next to the hand and 

 to language, probably the social relations of man have 

 been important in training his mind and developing his 

 brain. It is easily seen that the higher qualities of man, as 

 sympathy, love, unselfishness, heroism, and self-sacrifice, 

 are the qualities of mind, or " heart " as we sometimes say, 

 that would be given prominence in the home and the other 

 really social institutions. The study of man and his 

 social life is known as Sociology. 



FIG. 159. Diagrammatic horizontal section through the right eye of man. The 

 line ap is the axis of vision. The optic nerve leaves the eye toward the middle of the 

 head from this line, a.c., central artery; a.h., aqueous humor; b, blind spot, the entrance 

 of the optic nerve; c, conjunctiva; ch, choroid layer of the eyeball; c.L, crystalline lens ; 

 co, cornea, the transparent portion of the sclerotic coat; fo, point of clearest vision ; 

 O.H., optic nerve; r, the retina, or sensitive coat of the eye; sc, sclerotic coat; v.h., vitreous 

 humor. 



Questions on the Figure. Which is the essential sensory portion 

 of the eye? Which parts are supportive and protective? Which 

 parts are concerned with bringing the rays to a focus on the retina? 

 Why is an image formed on the retina of an object in front of the 

 eye? Consult your physics and determine the principles. 



