FERN FAMILY. 33 
FERN FAMILY—Filicineae. 
COMMON BRACKEN—Pteris aquilina L. 
The Bracken Fern grows commonly in pastures and 
old hayfields, especially in shaded parts, and also in open 
woods. It has long been suspected of containing a poison, 
but definite proof was wanting until the publication in 
1917 of the experiments of Drs. Hadwen and Bruce of 
the Health of Animals Branch of the Canadian Depart- 
ment of Agriculture. Their investigations have proved 
that it causes the disease called “staggers” which has 
given trouble to horse owners in British Columbia and 
some of the western United States. The following quota- 
tion from the work of these men will illustrate the extent 
of the harm which may be done: “During the hard winter 
of 1915-16 the mortality amongst horses in the Fraser 
Valley and on Vancouver Island was very heavy. As an 
extreme case we cite the following: In the little village 
of St. Elmo, B.C., out of twenty-four horses owned by 
eleven farmers, sixteen died of Bracken poisoning, four 
recovered, and the balance (four) did not take the dis- 
ease.” 
The symptoms of the poisoning were determined by 
feeding experiments with hay to which a definite amount 
of Bracken was added. No irregularity was 
noticed until after several weeks of feeding, the 
first indication being generally an unsteady gait, accom- 
panied by nervousness and constipation. Then the eye 
became congested, and later there was constitutional or 
systemic disturbance with manifest symptoms of in- 
toxication. Increasing weakness finally rendered the 
animal unable to stand, or even to lie in a natural posi- 
tion. In this condition he showed great excitement and 
usually battered himself up badly before death ensued. 
The appetite was good throughout. 
Symptoms 
