20 



tendency to develop tolerance for the poison. It may be that the slow 

 recovery is due more to the slowness with which the nervous system 

 recovers from the action of the poison than to the poison being retained 

 in the system. 



TABLE VII 

 The Narrow-Leaved Milkweed The Green Plant Fed to Cattle 



Amount j Time symptoms j Time of death j Final result 

 observed or recovery 



The foregoing table made from tests with yearling animals may be 

 briefly summarized for a stockman's use as follows: (1) amounts 

 below 2 pounds are not ordinarily dangerous; (2) amounts in excess 

 of 2 pounds and up to 5 pounds are dangerous; (3) amounts of 5 

 pounds or more may be reasonably certain of causing death; (4) there 

 is a wide variation in the susceptibility of individual animals, some 

 being poisoned with less amounts than others. 



TABLE VIII 



The Narrow-Leaved Milkweed The Green Pods Fed to Cattle 



. Negative 



This one feeding showed very clearh' from the view-point of a stock- 

 man that there is no increased danger from an animal eating pods, for 



(1) it takes a large number of the plans to produce 2^ pounds of pods, 

 a greater number than any animal would graze in any one time ; , and 



(2) if 2J pounds produce no symptoms of poisoning, it is plain that 

 the pods are not especially poisonous. 



The following table summarizes the feeding of air-dried narrow- 

 leaved milkweed to cattle. This material was cut green and allowed 

 to dry thoroughly in the sun; the weight when dry being approxi- 

 mately 66% less than the green weight: 



TABLE IX 

 The Narrow-Leaved Milkweed The Air-Dried Plant Fed to Cattle 



