THE WHORLED MILKWEED AS A POISOIsrOUS PLANT. 



33 



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 Asclepius 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 bettceen 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 



155 



Sheep 468 



September 8, dead 7.30 a. m 



August 18, died 6.30 a. m 



20 



Sheep 475 



August 17, 12.28 p. m 



18 



Sheep 476 



June 20, 12.22 p. m 



June 20, 3.45 p. m 



3 



