6 BULLETIN 1391, IT. S. DEPARTMENT OF AGRICULTURE 
The plant is found from southern Colorado to the Texas Pan- 
handle and south to Arizona, Sonora, and Chihuahua. It grows in 
great abundance in the irrigated portions of the Pecos Valley in 
New Mexico and Texas. 
Fig. 2. — A group of plants of Apiopap 
pus heterophyllus 
EXPERIMENTAL WORK 
About the middle of October, 1919, the writers visited the Pecos 
Valley with the intention of making some detailed feeding experi- 
ments in order to determine definitely whether the plant was poison- 
ous. After some preliminary in- 
vestigations it was decided to carry 
on feeding work at Roswell, 
N. Mex., which seemed to be the 
most available place for the work. 
With the assistance and cordial co- 
operation of the county agricul- 
tural agent, J. R. Thomas, and of 
George A. Lapp, of the Bureau of 
Animal Industry, arrangements 
were made for the necessary ex- 
perimental animals and accommo- 
dations for handling them, and the 
work was continued until January 
19, 1920. Glenwood C. Roe was left in immediate charge of the ex- 
perimental work. The main work was with cattle, but two horses 
were used also. 
With three of the cattle, Nos. 851, 853, and 854, it was planned to 
give them all the Aplopappus they would eat. The material was 
mixed with a little hay, in order to induce them to eat more readily, 
but no attempt was made to give them a maintenance ration of the 
hay. In order to eliminate definitely the question of starvation, 
steer No. 855 was given a maintenance ration of hay in addition to 
the Aplopappus. 
Of the four cattle used in the experiment, all died. Of the two 
horses, one died and the other showed pronounced symptoms. 
As controls, steer No. 852 and horse No. 134 were kept under the 
same conditions as the experimental animals, except that no Aplo- 
pappus was given them. 
The results of this work established the fact that Aplopappus is 
poisonous and produces the symptoms considered characteristic of 
the alkali disease. 
This work was continued at the Salina (Utah) experiment station 
during the summers of 1920, 1921, 1922, and 1923. Cattle and sheep 
were used and more complete data were obtained, especially in regard 
to symptoms, pathological effects, dosage, comparative toxicity of 
stems and leaves, possible remedies, and possibilities of transmission 
of the poison through milk. 
A thorough chemical examination of the plant by J. F. Couch, 
chemist in the Pathological Division, cooperating in poisonous-plant 
investigations, is well advanced. 
Table 1 gives a summarized statement of the results of the feeding 
experiments, 1919 to 1923, inclusive. 
