272 VETEEINAEY TOXICOLOGY 



The powdered root is irritant and laxative, and in large 

 doses causes haemorrhagic gastro-enteritis, and nervous 

 symptoms of drowsiness, occasionally convulsions, coma, 

 and collapse (Finlay Dun). Blindness often follows large 

 doses. The extract is prepared by means of ether, and 

 Frohner states that 5 drachms killed a dog of 40 pounds, 

 6 drachms a sheep of 88 pounds, and 3 ounces a cow of 

 660 pounds weight. 



In the treatment of male-fern poisoning oils must be 

 avoided. Castor oil greatly facilitates absorption, and ac- 

 cording to Kobert in 57 per cent, of cases of poisoning this 

 oil had been given. Evacuation of the stomach, mucila- 

 ginous medicines, and stimulants, are indicated as remedial 

 measures. 



Poisoning by Bracken {Pteris aquilma) is a so far 

 obscure disorder, often observed in cattle in the early 

 autumn (from August to November), after eating bracken. 

 The plant is taken, although other green food may also be 

 available. 



The poisoning of horses after prolonged feeding on bracken 

 along with other forage is mentioned by the German autho- 

 rities,* and is stated to be marked by timidity, uncertain 

 gait, loss of equilibrium, dilatation of the pupils, red, and 

 later yellow, coloration of the conjunctivse, and slowing of 

 the pulse. Sometimes death occurs. 



The poisoning is attributed by the Continental authorities 

 to the effects of an acid {pteritannic acid), similar to, and 

 possibly identical with, the filicic acid of male-fern. Both 

 these acids are, indeed, derivatives of the polyhydric 

 phenols (such as tannin, pyrogallol, and phloroglucinol). 

 Such poisoning of the horse does not appear to have been 

 observed in Britain, perhaps because the plant is rarely fed, 

 though used freely as a litter. 



The poisoning of cattle by bracken appears to have been 

 first distinctly recognised in Britain in 1893, in which year 

 D. M. Storrarf drew attention to the disorder, which he 



* See Mliller, LandwirthschaftUche Giftlehre, 1897, p. 29. 

 t Jl. Comp. Path, 1893, p. 276. 



