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this experiment ought to have been carried farther and thegrains from that tuft should have been sown in the ensuingcrop, to determine with certainty whether they were infected.
It docs not appear that the diseases of blight , mildew , andfust, are properly understood, and it is a doubtful point whe-ther these diseases can be correctly distinguished by the mostaccurate agriculturist. Without pretending to any minutepractical knowledge on this subject, blight may perhaps bedefined as an internal disease in the ear or spike of the wheat,either affecting all, or only a part of the florets, producing an en-tire or partial deficiency of seeds; or, in a lesser state of the dis-ease, rendering the grains small, shrivelled, and light. Mildewon the contrary seems to be an external disease, proceeding fromthe growth of a parasitical fungus or lichen on the straw orear, or both, which robs the plant of its nourishment, and oc-casions the grain produce to be shrivelled, small, and hungry.The former of these diseases, blight, is probably produced byheavy rains falling at the time when the wheat is in flower ;that is, when the anthers are protruded from the florets, andby which rains the pollen farina fxcundans, or vivifying dustof the anthers, is washed away, before it has come to sufficientmuturity to impregnate the stiles leading to the ovaries orreceptacles of the embryo grains or seeds. The latter, or mil-dew, so far as the reporter can judge from his own observation,and the information of others, proceeds from the prevalenceof heavy fogs or mists, or of cold drizzling rainy weather du-ring the summer months, between the times of flowering andripening ; which, by encouraging and promoting the growthof the parasitical lichen or fungus, which seems to constitutethe disease, injures the health of the wheat plant, and pre-vents it from perfecting its farinaceous seeds.
In 1808, 1809, and 1810, serious injury was suffered inmany parts of Britain by disease, and consequent defalcationof the wheat crop, which consisted of a combination of theblight and mildew as here understood, and appeared to have