400 
Journal of Agricultural Research 
Vol. IX, No. ix 
weed, a brief account of the symptoms observed in the experiments 
with sheep is pertinent. Considerable individual variation exists in 
the different animals, both in the period elapsing until the first 
symptom of trembles is apparent and in the period following until 
death ensues. Some were sick as early as three days after being placed 
on the experiment, and no effects were apparent for three weeks in 
other cases. Sheep usually live three or four days after the disorder is 
first noticed. Some remain alive, however, for nearly two weeks, and 
one animal characteristically affected entirely recovered. The feeding 
of E . ageratoides to this animal, however, was discontinued as soon as 
trembling was noted. 
Sheep in the early stages of the disease are sluggish and lie quiet unless 
urged to rise. They may refuse to eat, or the appetite may be quite 
normal. There is generally a very considerable decrease in weight, most 
of which occurs in the last two or three days preceding death. Respira¬ 
tions are accelerated and somewhat labored. A marked stiffness of the 
legs and ataxia characterizes the movements in walking. If after a day 
or two the animal is made to stand for a few minutes or is driven a few 
yards, muscular spasm, especially in the limbs, is evident. The sheep 
then stands with hind limbs placed well under the body (PI. 23, A) and 
all feet spread apart laterally. In this posture the back is bowed, the 
neck outstretched, and the head lowered. Within a few seconds the 
quivering spreads over the entire body, increases in intensity, and be¬ 
comes a violent, involitional tremor (Pi. 23, B). This is accompanied by 
slight, intermittent, tetanic contractions of the musculature of the limbs. 
At this stage of trembling ataxia is very pronounced, and the animal is 
unable to stand (PI. 24, A). It drops quickly into the normal resting 
posture (PI. 24, B), whereupon the trembling immediately ceases. If 
the sheep is made to rise after it has lain down for a few moments, a 
second spasm of trembling ensues, with a repetition of the symptoms as 
described. Trembling may recur repeatedly every time the animal is 
made to stand. The quiescent period is shortened, however, after each 
spasm of trembling and may begin as soon as the animal is placed on its 
feet. 
RESULTS OF EXPERIMENTS 
Experiment i. —Three ewes, No. 11, 26, and 10, were used in experi¬ 
ment 1, which was designed to determine whether harmful effects follow 
the feeding of E. ageratoides. This experiment was begun on June 17 
and closed on August 2. However, from June 22 to July 6 and from July 
18 to July 28 it was impossible to secure the weed. During these periods 
the animals were grazed on Bermuda grass pasture. Except during the 
two periods mentioned, a liberal supply of white snakeroot was fed 
just as it arrived from the point of shipment. In addition, a mainte¬ 
nance ration of grain was fed in a separate trough. Neither the weeds 
