ECONOMIC IMPORTANCE OF FUNGI 311 
portant and effective. The most effective prophylactic 
measures are the following: 
1. Personal hygiene, involving bodily cleanliness, tem- 
perate habits, and careful diet. With plant diseases 
hygienic measures include such practices as sterilizing 
seeds before planting, by rinsing them in solutions of 
some germ-killing substance, like formaldehyde; spray- 
ing diseased trees with fungicides (fungus-killing solu- 
tions) ; washing the branches and foliage with various solu- 
tions, such as whale-oil soap (good for scale insects) ; and 
painting the cut surfaces of trees, after trimming, to 
prevent the mycelium of germinating fungus spores from 
entering the woody tissue. 
2. Public hygiene, or sanitation, which means maintain- 
ing healthful surroundings. In the case of animal dis- 
eases this includes preserving a pure public water supply, 
proper sewage systems, clean streets, a pure milk supply 
(especially a healthful condition of the cows and their 
surroundings), and a careful inspection of meat and all 
other foods shipped and sold in public. 
In the case of plants, sanitation includes preserving 
a proper drainage and aeration of the soil; maintaining a 
pure atmosphere, and especially one free from smoke and 
the poisonous gases that accompany it; fumigating in 
plant houses with potassium cyanide fumes, or with to- 
bacco smoke to kill scale insects, and other insects, the 
burning up of trees or other plants infected with a trans- 
missible disease, such for example, as the chestnut bark 
disease, or barberry bushes carrying wheat rust, and 
eradication of injurious fungi from the soil of cultivated 
fields by crop-rotation, as indicated in Chapter VII. 
3. Quarantine. This is a method of sanitation by which 
