In regard to possible poisonous properties, it must be said that the facts are at present somewhat uncertain, but a number of authorities clearly regard the Bracken as poisonous. (a) Müller (1897) records the poisoning of horses which ate it for some weeks with chaff—and some died. (b) Chesnut and Wilcox (1901) say that cases of poisoning of horses and cattle have been reported from England and a few localities in the United States. (c) Pott states that when eaten in quantity by cattle Bracken causes hæmaturia, and in horses nervous symptoms (brain trouble), sometimes with fatal effects. (d) Pammel also remarks on the believed poisonous character of this plant. (e) In view of its suspected poisonous character feeding experiments were conducted by the Board of Agriculture and Fisheries with a large quantity of Bracken, but the results were negative, yielding no experimental proof of the plant being poisonous. One animal—a heifer—consumed 60 lb. of Bracken between Aug. 14 and Aug. 20, and after two meals containing about 30 lb. of Bracken showed only symptoms of indigestion. After the 60 lb. there were no symptoms of illness. It has been thought possible that the so-called Bracken poisoning is due to Potentilla Tormentilla (q.v.).
In 1893 Storrar dealt with the question and expressed the view that any disorder due to Bracken was probably not a toxic effect but a digestive trouble simply (Jour. Comp. Path., 1893).
Toxic Principle. Continental authorities say that Bracken contains the poisonous Pteritannic acid, which is identical with the Filicic acid of the Male Fern (Aspidium filix-mas).
Symptoms. In the cases of horses which died Müller gives the symptoms as timidity, slower movement or action, loss of balance, dilated pupils, reddening followed by yellowing of the conjunctivæ, and slowing of the pulse.
Pammel notes Bracken as an astringent and anthelmintic, and also says it causes enteritis, spasms, and paralysis.
REFERENCES.
[10], [25], [57], [190], [203], [204], [213].
FUNGI[[6]].
Ergot (Claviceps purpurea). This fungus, parasitic on rye and a number of grasses, has long been known to induce distinct poisonous effects on man and domestic animals when ingested in sufficient quantity.
[6]. Poisonous parasitic fungi generally are not dealt with in this volume, but ergot is included because it is widely distributed and perhaps the best known, while its effects have been fully studied.