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. 



