re 
oy) 
PRINCIPLES OF BOTANY, ETC. 
§ 330. 
Gangraena. Plants affected with gangrene be: 
come soft and moist in some single parts, which 
at last dissolve in a foul ichor. It chiefly at- 
tacks fruits, flowers, leaves and roots, rarely the 
stem. Gangrene arises either from too wet or too 
fat and luxurious ground, from infection and con- 
tusion. It scarcely admits of a cure, especially as 
it only infests single parts, but may be prevented by 
a removal of its causes. 
§ 331. 
Ustilago. ‘This singular variety of gangrene oc- 
curs most frequently in the species of gramina, 
rarely in other plants; sometimes in Scorzonera, 
Tragopogon, &c. It arises from a small fungus, 
which occupies the whole ear, (arista), which there- 
fore cannot form itself properly. Every part of it, 
on the contrary, becomes a black, soiling mass. 
Moist seasons are most favourable for it, and its 
progress is under such circumstances very rapid. 
That corn may not be affected with it, such grain 
only should be sown, which has not been kept in 
damp places, nor has been got from where the dis- 
ease prevailed. Neither should the grain be placed too 
deep in the ground, especially where the soil is fat, 
and the ground moist. When, however, it has once 
begun, the plants diseased cannot be cured. In 
tender and scarce garden plants, something may be 
done by amputating the diseased part just forming. 
But 
