MteXICAlSr 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. verticilJata 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 wnth the 

 nose extended forward. The pulse was always liigh 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 arc 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 exphation, 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 ^4. galioides showed a decline in temperature before death 

 (Bui. 800, p. 26), while in the ^4. mexicana and ^4. 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, Slieep 

 478, recovered after passing into the stage of spasms. Of the shoop 

 poisoned by .4. pumila only two exhibited spasms, and they died. 

 Only three sheep were poisoned ])y ^4. vertlcillata 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 

 sym})toms. 



The average time of 14 hours and o minutes l)otween the time of 

 feeding and beginning of symptoms is probabl}^ 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 



