In a field of rye, especially after a wet sowing or a wet season of growth, a certain proportion of the heads bear long brown or purple corns, one or more upon a head, projecting in the shape of a cock’s spur, whence the French name of ergot. The spur appears to be, and probably is, an overgrown grain of rye; it is grooved like a rye-corn, occupies the place of the corn between the two chaff-coverings, and contains an abundant whitish meal. Microscopic research has detected in or upon the spurred rye the filaments of a minute parasitic mould; so that it is to the invasion by a parasite that we may trace the enormous overgrowth of one or more grains on an ear, and it is probably to the ferment-action of the fungus that we should ascribe the poisonous properties of the meal. The proportion of all the stalks in a field so affected will vary considerably, as well as the proportion of grains on each affected head of corn[112]. Rye affected with ergot is apt to be a poor crop at any rate; one or more spurred corns on a head tend to keep the rest of the grains small or unfilled; and if there be many stalks in the field so affected, the spurred grain will bulk considerably in the whole yield. When the diseased grains are ground to meal along with the healthy grains, the meal and the bread will contain an appreciable quantity of the poison of ergot; and if rye-bread were the staple food, there would be a great risk, after an unusually bad harvest, of an outbreak of the remarkable constitutional effects of ergotism. Rye-bread with much ergot in it may be rather blacker than usual; but it is said to have no peculiar taste.
It is almost exclusively among the peasantry that symptoms of ergotism have been seen, and among children particularly. The attack usually began with intense pains in the legs or feet, causing the victims to writhe and scream. A fire seemed to burn between the flesh and the bones, and, at a later stage, even in the bowels, the surface of the body being all the while cold as ice. Sometimes the skin of affected limbs became livid or black; now and then large blebs or blisters arose upon it, as in bad kinds of erysipelas. Gangrene or sloughing of the extremities followed; a foot or a hand fell off, or the flesh of a whole limb was destroyed down to the bones, by a process which began in the deeper textures. The spontaneous separation of a gangrenous hand or foot was on the whole a good sign for the recovery of the patient. Such was the _ignis sacer_, or _ignis S. Antonii_ which figures prominently, I am told, in the French legends of the Saints, and of which epidemics are recorded in the French medieval chronicles. Corresponding effects of ergotism may or may not have occurred during the medieval period in other countries of Europe where rye was grown.