100 



an accidental carrier of some pathogenic organism. According to reports, 

 the same flora may be in areas in which 'trembles' occur as in those free 

 from it, and milk-sickness is also said to occur where no vegetation grows 

 (inclosed pens). The disease also has disappeared from an area after 

 simply clearing the woodland where it occurred and turning it into pasture. 

 Again, severe epidemics have occurred in winter when the foUage has 

 disappeared, which would tend to exclude the higher, non-evergreen plants 

 as the cause of this disorder." 



The later experiments however, of Curtis and Wolf, as well as those 

 of Marsh and Clawson (1917) are conclusive in showing that, apart from 

 the evident connection of milk-sickness with the symptoms caused by the 

 ingestion of snakeroot, there is no doubt that this plant is poisonous to 

 stock. The former says : . . . ''white snakeroot had previously been 

 claimed by Moseley to cause trembles in animals. This claim has been 

 substantiated by experiments with sheep in which green plants of E. 

 ageratoides were ied^^ ; and the latter : ". . . it has been clearly demon- 

 strated that E. urticaefolium must be counted as one of the rather important 

 stock-poisoning plants which produces serious losses of domestic animals." 

 These experiments also showed that the plant loses a large part of its 

 toxicity in drying. 



In the following year, 1918, the experiments of Wolf, Curtis & Kaupp, 

 in North Carolina, also proved that trembles and milksickness were due 

 to this plant. According to them, the disease may appear ''at any season 

 of the year, but is most prevalent in late summer and autumn, especially 

 when other vegetation is scarce because of drought. The disease is 

 frequently fatal in domestic animals while the sequel of milksickness in 

 man, in case of recovery, is lasting debility." "During the experimenta- 

 tion, 31 fatal cases of trembles and milksickness have been developed 

 among the 44 ewes and lambs that were employed in some phase of the 

 experimentation involving the feeding of white snakeroot. Two of these 

 lambs contracted genuine cases of milksickness by suckling their mothers, 

 demonstrating that the disease may be transmitted through the milk. 

 This fact has for a long time been a matter of common belief among 

 farmers. Furthermore, animals in lactation, having access to white 

 snakeroot, may be apparently normal yet are capable of transmitting 

 milksickness through their milk." 



Animals Affected: — The experiments referred to above proved 

 that white snakeroot was poisonous to all domestic animals. 



Symptoms: — The action of the poison is cumulative. The general 

 symptoms as given by Marsh and Clawsoft are, trembling, especially of the 

 nose and legs, more marked after exercise; depression and inactivity; 

 constipation with nausea and vomiting; pronounced weakness; difficulty 

 in standing, the animals sometimes remaining down for a prolonged period 

 before death. 



