MEANING OF DISEASE 451 
or easy functional activity. Despite, catition and care, 
therefore, health is often disturbed because of hereditary 
influences. Thanks to science, many of the old bugbears 
of the past, however, have become eee: and their 
true import set right. 
5. Germs and parasites.—Parasites 24 bacteria, or 
germs, cause much loss to live stock. Typical illustra- 
DISEASED AND NoRMAL LUNGS 
Diseased lung at left; healthy, normal lung at right. 
tions of such are hog cholera, a germ disease; tubercu- 
losis, a germ disease ; stomach worms, parasites ; staggers, 
a mold disease; and abortion, a germ disease. These 
and hundreds like them are all due to parasites or germs. 
As disease agents they disturb and destroy, regardless of 
age, class or breed. 
Remedies and treatment are being sought to meet these individual 
diseases as they occur. Nevertheless, the best treatment is preven- 
tion, It is far better to prevent than to cure; and that is the line 
