EUPATORIUM AGERATOIDES, THE CAUSE OF 
TREMBLES 1 
By R. S. Curtis, Animal Husbandman , Beef-Cattle and Sheep Investigations , and 
Frederick A. Wolf, Botanist , North Carolina Agricultural Experiment Station * 
INTRODUCTION 
In the mountainous sections of North Carolina considerable losses of 
domestic animals annually occur from a malady known as trembles. 
This disease is said to be transmissible to man through the ingestion of 
milk, certain milk products, or flesh of animals affected with trembles, 
and is known by physicians as milksickness. Since trembles is of so 
much economic importance to the live-stock interests pf the State and 
since the investigations dealing with its etiology contain such diverse 
conclusions, a study of this disease was begun during 1916. It is deemed 
advisable to present at this time the considerable body of data which has 
accumulated relative to the relationship between Eupatorium ageratoides 
(Pl. 22) and trembles and to reserve for future investigation many im¬ 
portant considerations which are as yet unknown or lack conclusive 
data. Data on certain other phases of the problem have already been 
secured, but a report of this part of the investigation is reserved for future 
publication. 
HISTORICAL REVIEW 
A very large number of papers dealing with milksickness, or trembles, 
have appeared in the hundred or more years during which the disease 
has been known. Most of these articles have been published in the 
various medical journals, and references to the most important of them 
are given in several of the more recent investigations (i, 2, 3, 4, 5, 6). 8 
These recent papers, furthermore, contain a brief r 4 sum 6 of the im¬ 
portant findings of the earlier students of this disease, so that it is neces¬ 
sary for the present purpose to review only the pertinent facts relative 
to the causes which have been regarded as productive of trembles. In 
general, these etiological factors may be placed in one of three groups— 
namely, mineral poisons, poisonous plants, and bacterial parasites. 
Arsenic, lead, and cobalt are among the minerals which have been 
suspected of being the cause of the trouble, but these charges have 
been disproved. 
Among the poisonous plants whose ingestion is regarded as the cause 
of the trouble are Rhus toxicodendron , Eupatorium ageratoides , Lobelia 
in flat a, and Bigelovia {Isocoma) heterophylla. Moseley (4) was of the 
1 Published with the permission of the Director of the North Carolina Agricultural Experiment Station. 
1 Grateful acknowledgment is hereby made of the kindly assistance in this work of our colleagues Mr. 
Earl Hostetler and Dr. J. I. Handley. 
* Reference is made by number to “ literature cited,” p. 404. 
Journal of Agricultural Research, 
Washington, D. C. 
ih 
Vol. IX, No. 11 
June n, 1917 
Key No. N. C.—6 
(397) 
