PRESERVATION BY DRYING. 237 
molds that cause their decay, since their uninjured skins resist their 
entrance. The smooth hard skin of many fruits is impervious to 
the mycelium of the mold, though it can readily force its way in 
through a bruise or crack into the softer substance within. Hence 
the bruised apple decays quickly. Wiping the skin of fruit clean 
and dry will protect it for a long time from decay. The wiping 
cleans off most of the mold spores that may be on the skin, and the 
drying of the skin leaves no moisture in which the few spores left 
can germinate. If moisture condenses on the skin, as when the 
fruit is taken from a cold room into a warm one, decay is sure to 
follow, since this moisture starts the germination of the spores into a 
mycelium and the latter is pretty sure to find some place in the skin 
through which it can pass. Once inside the skin, it grows rapidly 
through the soft pulp and the fruit is soon spoiled. The preserva- 
tion of fruit is, thus, a matter of keeping it dry, at a low temperature, 
and with an unbroken skin. Even the wrapping of fruit in paper 
materially aids in its keeping, since the paper absorbs the moisture 
that collects on the skin. 
PRESERVATION BY DRYING. 
The simplest means of preventing the growth of bacteria in food 
products is by drying. Anything that can be dried without destroy- 
ing its value as a food can in this way be effectually protected 
against bacterial action. No method of preserving food products is 
so universally used as this, and none other is so effective. 
Grains. In the preservation of the valuable cereal products 
nature herself adopts this plan and, when the grain is ripening, the 
large amount of water which was present in the green seed disap- 
pears, leaving the ripened grain, somewhat shriveled, perhaps, but 
with a very small water content. Such dried grains not only refuse 
to germinate unless moistened with water, but bacteria are utterly 
unable to grow within them. Nature wishes to preserve the grain 
through the season of rest (winter), and in order to protect it from 
bacteria she takes most of the water out, thus preventing the putre- 
faction which would otherwise surely take place. In harvesting 
