“The term _loco_, simply meaning foolish, is applied because of the peculiar form of dementia induced in the animals that are in the habit of eating the plant. Whether the animals (horses chiefly) begin to eat the plant from necessity (which is not likely) or from choice, I am unable to say. Certain it is, however, that when once commenced, they continue it, passing through a temporary intoxication, to a complete nervous and muscular wreck in the latter stages, when it has developed into a fully marked disease, which terminates in death from starvation or inability to digest more nourishing food. The animal, toward the last, becomes stupid or wild, or even vicious, or again acting as though attacked with blind staggers.” (Dr. Rothrock, Report of Dept. of Agriculture, 1884). Dr. Isaac Ott, of Easton, Pa., gives the following as the physiological action of the Astragalus Mollissimus: “It decreases the irritability of the motor nerve, greatly affects the sensory ganglia of the central nervous system, preventing them from readily receiving impressions. Has a spinal tetanic action. It kills mainly by arrest of the heart. Increases the callory secretion. Has a stupifying action on the brain. Reduces the cardiac force and frequency. Temporarily increases arterial tension, but finally decreases it. Greatly dilates the pupil.” (_Amer. Jour. of Pharmacy_, 1882). In opposition to these statements Professor Sayre, of Kansas, after an extended observation, arrived at the conclusion that “it is a grave question whether loco weed is a poison at all; upon chemical examination no poisonous principle of any kind was discovered; no toxic effect was observable when administered to frogs, cats, dogs, or the human species, ... the point cannot be accepted as a settled one whether loco is poisonous to cattle or not.” Dr. G. C. Faville found in _locoed_ sheep in Colorado bunches of tapeworms in the gall ducts. Dr. Cooper Curtice, who subsequently studied the subject, found the tænia fimbriata, and believes that to these the symptoms are exclusively due. “The affected lambs are large headed with undersized bodies and hidebound skins. Their gait is slightly like that of a rheumatic. They seem to have difficulty in cropping the shorter grass; they also appear to be more foolish than the other sheep, standing oftener to stamp at the sheep dogs or the herder than the healthier ones. Others do not seem to see as well, or are so affected that they seem to appreciate danger less. In driving, they are to be found at the rear of the flock.” (Animal Parasites of Sheep.) It is altogether probable that the tæniasis of sheep has been mistaken for _loco_, but this can hardly account for the remarkable symptoms found in other genera of animals, as a concomitant of an acquired and insatiable fondness for these leguminous plants. The tænia fimbriata has been found in sheep and deer, but there is no record of it as a parasite of cattle and horses.