86 PASTURE AND RANGE. 
There are few American plants whose poisonous prop- 
erties have caused so much controversy as those of 
White Snakeroot. The disease called ‘“‘trem- 
Trembles or : : 
Milksickness Dles,” which has lately been conclusively 
traced to it, was for many years a mystery. 
The trouble was formerly prevalent among animals feed- 
ing in wooded pastures, affecting more especially cattle 
and sheep, particularly in some of the eastern and central 
United States. It was variously attributed to bacteria, to 
a poison in the soil, to exhalations from the swamps, and 
to the bites of insects or small arthropods. Farmers 
learned that if they fenced their cattle away from the 
woods and swamps the disease did not trouble them. The 
serious character of the disease was increased by the fact 
that it was communicated to human beings by the milk 
of animals suffering from it. People who acquired it 
rarely recovered, and those who did survive were victims 
of permanent nervous debility. The fact of its communi- 
cation by means of milk led to the application of the 
name “milksickness” to the disease. 
The symptoms usually develop when cattle are out in 
pasture. Some stockmen believe that the disease is more 
prevalent in autumn. This may be due 
partly to the fact that unusual exercise and 
excitement hasten the development and in- 
crease the intensity of the symptoms, so 
that the disease becomes more apparent at the time when 
stock is being driven to market. The scarcity of other 
pasture at this season would also lead to the ingestion 
of larger amounts of the plant. In rare cases animals are 
attacked in winter, when, according to experienced stock- 
men, the disease comes as a result of the feeding of 
swamp hay. This fact is significant, as such hay is the 
only winter feed likely to contain White Snakeroot. 
Conditions for 
Development of 
Disease 
