The Bulletin 
69 
tlie others may be classified as supporting either (1) the mineral poison 
theory, (2) the germ or microbic theory, or (3) the poisonous plant theory. 
4. The first claim that white snakeroot, Eupatorium urticsefolium, is re¬ 
sponsible for the disease seems to have been made as early as 1S40. The ob¬ 
servations and experiments of several subsequent writers support this claim 
as do the present experimental studies. 
5. There are about forty species of Eupatorium in the southern United 
States, none of which species except white snakeroot are known to be poison¬ 
ous, although several species are used medicinally. White snakeroot is com¬ 
monly present in shady, mountainous situations in western North Carolina, 
and is distinguishable with difficulty from some of the species of Eupatorium, 
except by one with experience in identifying plants and by the exercise of 
close observation. 
6. In previous accounts, the symptoms of the disorder appear to have been 
described in detail only in the case of cattle and of man. The writers have 
not had occasion to see the disease in cattle or in man and in their studies 
have employed ewes, lambs, hogs, dogs, guinea pigs, and mice. Trembles was 
developed in sheep, hogs, and guinea pigs, and the symptoms of the disorder 
have accordingly been described with considerable fullness and illustrated 
photographically. The symptoms in sheep and hogs are sufficiently character¬ 
istic so that any one who has ever seen an affected animal may be certain of 
his diagnosis. 
7. 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. 
8. The present experiments were conducted at West Raleigh, N. C., about 
400 miles distant from the place of collection of the white snakeroot used, 
and no case of trembles or milksickness had ever appeared in West Raleigh 
prior to the performance of these feeding tests. 
9. During the experimentation, 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 snake¬ 
root, may be apparently normal yet are capable of transmitting milksickness 
through their milk. 
There was no other contributory cause of death of these 31 animals except 
in the case of two individuals, in which cases stomach worms may have been, 
in part, responsible for death. 
One of the two hogs employed in the experiment developed a typical case 
of trembles. 
Fifteen of the 29 guinea pigs died from the feeding of white snakeroot or 
its products. 
It is not possible to determine with certainty whether death resulted from 
the feeding of butter in the case of two of the three mice employed, although 
it is logical, in view of the experiments with suckling lambs, to believe that 
the disease may be transmitted through the agency of butter. 
