but still what is there to show that the injury resulted from a sudden return of the stimulus of heat, rather than from a sudden abstraction of it?
Mr. Egremont has omitted to state whether the mildew in that part of the country where he made his observations affected the summer corns, barley, oats, &c. as well as wheat. He says that the disease made its appearance about a week after this extraordinary change in the temperature of the air. One is curious to know whether he had made any accurate observations on the state of the straw in its earlier stages, and whether the disease might not have existed long before it excited his notice? If the mildew makes its appearance for the first time so late as the last week in July, there seems no reason why it should not attack with equal frequency and fatality the summer corns as the winter ones; but it certainly does not: we rarely see barley or oats injured by the mildew. General as the complaint is of mildew among the wheats this year, we have heard of but little injury from that cause among the summer corns: their unusual brightness is presumptive of their exemption from mildew.
Mr. Egremont says that as far as his observation has extended, the degree of injury to the corn is not always nor necessarily connected with the appearance of the straw; having found both the straw and ear with a favorable appearance when the grain has proved exceedingly small and partially fed; "not unfrequently one end of the grain pretty well fed, while the other has been much shrivelled." Where the ear is partially blind, or where without any external appearance of injury to the straw, the corn is light and shrivelled, I should be much inclined to suspect that the mischief arose from an insufficient impregnation. The accidents of weather may have rendered the process of fecundation abortive; but this barrenness has no relation to the mildew. Or the injury may have arisen, as I have suggested to have been the case this year with the barley crop, from a sort of precocity, a premature ripening, a too rapid conversion of the milk of the young kernel into farinaceous substance, occasioned by unusual drought and heat.
The following case is produced as a strong one in favor of a physical to the exclusion of a mechanical affection: "In a district called Marshland, in the West Riding of Yorkshire, the culture of potatoes is carried to a very great extent; consequently great quantities are planted late in the summer, and depend on a favorable autumn for an abundant produce. Early frosts frequently disappoint the cultivator, sometimes by coming so soon as the beginning of September. After the frost, during the early part of the succeeding day the mischief is scarcely perceptible, and ultimately
