110 
THE PRINCIPLES OF BOTANY. 
grains will be thin and starved, and so, indeed, will they 
from another affection, which must not be confounded with 
the present. 
Of late years an insect attack has increased in prevalence, 
which is due to a fly called the Anthomyia tritici, American 
wheat-midge or Hessian fly. This creature lays its eggs in 
the chaff scales of wheat, which ultimately produce minute, 
bright orange-coloured larvae. 
Of course, the motions of these insects readily distinguish 
them from the vegetable attack, at the same time the evil 
effects of both are much the same ; and without further study 
we are simply beaten by these minute and apparently insig- 
nificant creatures. 
4. The U. linearis, as its name imports, will be found on 
the plant in smaller linear patches. In this way the leaves 
of wheat and other grasses, both cereal and pastoral, are 
often attacked to such an extent that, in walking through 
them, the brownish-yellow spores of the fungus which 
inhabit these lines will completely cover one’s boots with its 
yellow dust. This is highly injurious to the yield of the 
crop, and besides, it aids in the injury of the straw for fodder 
purposes. 
Cold damp springs, want of drainage, and whatever tends 
to the want of a thorough adaptation of the surrounding 
circumstances to the wellbeing of the plant, is sure to produce 
this “ rust/’ so called from its peroxide-of-iron appearance 
and colour. 
Generally stated, we may say that any of these smuts and 
rusts not only lessen the produce of corn, but act very pre- 
judicially upon the straw likewise. Hence it is always very 
important that, in selecting straw for chaff, or in employing 
it as fodder in the straw yard, brightness of colour, and a 
smooth, unbroken epidermis, should be attended to, for if 
not our cattle will, as a rule, fare but badly, when they 
might, from the quantity allowed, be expected to do better. 
Again, rusts on grass leaves and smuts to the flowers 
argues a state of out-of-condition in the meadow that will 
require most anxious attention — facts which will come out 
more fully as we examine some allied genera. 
Our present history of the Agricultural Uredines will be 
imperfect if we forget to mention the U. betas, which is 
sometimes found so abundant on the leaves of the beets and 
and mangold wurtzels of the farm. 
A few cold evenings towards the autumn will cause the 
leaves of these plants to be dotted over with yellow pustular 
