THE WHORLED MILKWEED AS A POISONOUS PLANT. 
3'3 
It must be remembered, too, that all these sheep were treated 
under corral conditions. It may be questioned whether the dosage 
would apply to sheep in pasture or on the range. Under the condi- 
tions which have existed in most recorded cases of poisoning, how- 
ever, it is not probable that the dosage would have been much higher 
than in the experimental animals. In these reported cases, hungry 
animals have been more or less narrowly confined to areas on which 
the main vegetation was Asclepias galioides. Under such circum- 
stances, as is well known, animals will eat large quantities in a 
very short time. Not only does their hunger make them eat rap- 
idly and greedily, but jealousy of one another leads them to eat even 
more. It may be assumed then that grazing sheep may eat rapidly 
enough to make the dosage nearly or quite as small as in the case 
of the experimental animals. In comparing Sheep 509, which ate 
the plant, with grazing animals, it should be noted that range sheep 
do not eat so readily in corrals as on the range, and it is reasonable 
to suppose that a grazing sheep would be poisoned fully as quickly 
as a corral sheep. 
SUSCEPTIBILITY OF DIFFERENT ANIMALS. 
So far as the experiments show it appears that sheep and horses are 
about equally susceptible to poisoning from the plant. The method 
of feeding Sheep 509 and Horse 126 was the same, so that the two 
animals can be compared with each other. The lethal dose of the 
sheep was practically the same as the dose which produced violent 
illness in the horse. The dosage for Steer 750 was much greater, 
from which it seems probable that cattle are less susceptible than 
either sheep or horses. It does not follow, however, that horses are 
more liable to be poisoned than cattle, for horses are more particu- 
lar about eating and there is less probability at any time of their 
eating any considerable quantity of injurious plants. 
DELAY IN DEVELOPMENT OF SYMPTOMS. 
The following table shows the time which elapsed after the plant 
was given before the symptoms appeared: 
Table 3. — Time elapsed between feeding of plant and development of symptoms. 
Animal. 
Date and hour of feeding. 
Date and hour of symptoms. 
Time 
elapsed 
before 
symp- 
toms. 
1918. 
Horse 126 
July 30, 3.35 p. m. to 5.15 p. m 
July 31, 7.45 a. m 
Hours. 
14 
Steer 750 
August 26, 12.05 p. m. to 
August 27, 9.13 a. m 
21? 
Steer 750 
September 22,10.45 a. m. to 12 noon 
September 7, 11.12 a. m 
September 23, 3.45 a. m 
T5f 
Sheep 468 
Sheep 475 
Sheep 476 
September 8, dead 7.30 a. m 
August 18, died 6.30 a. m 
20 
August 17, 12.28 p. m 
18 
June 20, 12.22 p. m 
June 20, 3.45 p. m 
3 
