82 Smuts [CH. 
or chaff to gape. Their appearance varies with the 
different varieties of wheat. In most it is short, 
swollen, and almost spherical. In some, however, 
instead of shortening it becomes longer. The groove 
is never so pronounced as in healthy grains and in 
some cases is very shallow. The bunted ears are 
usually darker as the grain is greyish or greyish black. 
By rubbing an infected grain between our fingers, 
we shall be provided with the means of recognizing this 
disease on future occasions. It gives off a very dis- 
agreeable odour—somewhat resembling stinking fish— 
which clings to the fingers for some time. 
It does not attack the chaff but only the interior 
of the grain. The coat of the grain is not broken, and 
inside are many dark-brown spores. There are two 
species of bunt, Tilletia caries (see Fig. 26), which 
has rough spores, and Tilletia levis, which has smooth 
spores. 
In many cases all the spores are rough, indicating 
the presence of Tilletia caries, but in some cases the 
smooth spores of Tilletia levis may be mixed with 
them and in a few cases all the spores may be 
smooth. As these two species behave in a similar 
manner, we shall confine ourselves to the former. 
The spores are almost spherical and their surface has 
a rough, warty appearance. They are very small, 
being about ;,4, of an inch in diameter. In the case 
of this fungus the diseased grains are harvested with 
the good ones and on threshing some of them are 
crushed with the result that the spores get on the sound 
grain. When this wheat is sown the spores germinate, 
and eventually the young wheat plant is infected. The 
brown spores yield a crop of secondary spores, and these 
