The losses caused from the loco disease are very heavy in nearly all the Rocky Mountain States. The locoed condition is so commonly observed among sheep and horses that cases are not reported, and it is practically impossible to learn the exact extent of the disease. In the Judith Basin one prominent stockman was nearly ruined financially by the prevalence for a number of years of the loco habit among his sheep. In another instance the raising of horses was abandoned over a large tract of country on account of the loco weeds. The loco disease occurs under two forms—an acute and a chronic. An acute case of loco disease was observed by Dr. Wilcox in a two-year-old ewe with a lamb at its side. The ewe was observed eating large quantities of white loco weed on May 22nd, 1900. During the afternoon of the same day it became unmanageable, and the lamb was badly affected. An examination of the ewe at this time showed that it was completely blind and was affected with dizziness. It walked around in long circles to the right, and after a short period remained standing for a few moments in a sort of stupor. At the beginning of each attack the head was elevated and drawn to the right; eyelids, lips, and jaws were moved rapidly. Each attack lasted from one to two minutes and the intervals between the attacks lasted about five minutes. The second day the attacks became more severe and of longer duration, the head being turned more decidedly to the right and the animal sometimes falling upon the ground. Similar symptoms, accompanied by digestive disturbances, were manifested by the lamb during the second day, and it died during the afternoon. On the morning of the third day it was found that the ewe was pushing against the fold, and had apparently been in that position during the greater portion of the night. The animal then began to whirl round to the right. Later it became unable to stand, and the spasmodic movements were largely confined to the legs. On the morning of the fourth day it died. The pupil of the eye was at no time dilated, and the expression was nearly normal. The pulse was at first very irregular, but on the second day became again regular and of normal frequency. The only remedy which was tried was frequent injections of one-quarter grain doses of morphine, but this was without effect. Two other ewes ate smaller quantities of loco weed at the same time and were similarly affected, but less severely. In these cases morphine was tried with better success. The lambs, however, died from the poisonous properties contained in the milk of the mother.