MEXICAN" WHORLED MILKWEED AS A POISONOUS' PLANT.- 7 
RESULTS OF EXPERIMENTAL WORK AND CONCLUSIONS. 
SYMPTOMS. 
The symptoms exhibited by poisoned animals paralleled very 
closely those seen in cases poisoned by the other whorled milkweeds, 
A. galioides, A. pumila, and A. verticillata var. geyeri, differing little 
except in degree. 
There was depression with staggering, the weakness being espe- 
cially marked in the hind legs. As in the A. pumila cases, while 
standing the animals frequently held the head rather high with the 
nose extended forward. The pulse was always high and rather weak. 
These were the only symptoms in the milder cases, if we except a 
slightly higher temperature. 
In the severe cases the stage of weakness was followed by a stage 
in which there were spasms, mostly clonic, like those exhibited by 
animals poisoned by A. galioides. The animal would throw itself 
about violently, sometimes showing an opisthotonic position in its 
spasms, sometimes drawing the head toward the chest. Walking 
and running movements, while lying on the side, accompany the 
spasms, and frequently there are convulsive movements of the jaw. 
Two of the fatal cases were salivated and one was bloated. The 
animals groan, and in breathing there is frequently a marked interval 
between inspiration and expiration, the expiration being more or less 
violent. The temperature rises during the spasms. In Sheep 590 
it reached 107.7° F. and in Sheep 595, 106.4° F. These maximum 
temperatures were taken just after the death of the animals. In 
this connection it is interesting to note that temperature observa- 
tions on A. galioides showed a decline in temperature before death 
(Bui. 800, p. 26), while in the A. mexicana and A. pumila cases (Bui. 
942, p. — ) the maximum was reached at the time of death. In all 
whorled-milkweed cases the prognosis of those which pass into the 
stage of spasms is bad. 
Only three of the A. mexicana cases showed spasms, and they died. 
Of the A. galioides cases described in Bulletin 800 only one, Sheep 
478, recovered after passing into the stage of spasms. Of the sheep 
poisoned by A. pumila only two exhibited spasms, and they died. 
Only three sheep were poisoned by A. verticillata var. geyeri; all re- 
covered, and two went into the stage of spasms. 
DELAY IN DEVELOPMENT OF SYMPTOMS. 
Table 2 shows the time which elapsed before the appearance of 
symptoms. 
The average time of 14 hours and 5 minutes between the time of 
feeding and beginning of symptoms is probably slightly high. A few 
sheep showed symptoms when first seen in the morning and may 
have been sick for some time previously. Then, too, in cases which 
