170 
ELEMENTARY AGRICULTURE 
caused by parasitic growths or plant molds, known as 
fungi. Their threads and cells are too small to be ob¬ 
served by the eye and must be highly magnified for 
observation. It is known that various kinds of fungi 
may live in cotton or corn plants for several weeks with¬ 
out entirely killing the stalks. Cotton wilt is caused by 
an infection of the plant. The smut balls on the corn 
stalk are really the spore stage of a fungus which began 
to grow in the plant during its germination. It is im¬ 
possible to make a germination test to determine which 
Fig. 124 .—Increasing yields with good seeds. 
stalks of corn will be diseased, but we can make tests to 
eliminate the ears which are weak and show signs of 
being diseased. 
Methods of Testing.—The seed germinator box, rag- 
doll, blotting paper, and box methods of testing seeds are 
used. All of these methods are valuable for detecting 
weak seedlings. 
The Rag Doll—Perhaps the greatest advancement 
in seed testing has been made with corn. This is prob¬ 
ably due to the fact that the ear of corn is convenient to 
handle as a unit. In ea;ch case the ears should be num- 
