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4 io ECONOMIC AND TECHNICAL
C. LICHENS AS POISONS
Though the acid substances of lichens are most of them extremely
irritating when taken internally, very few lichens are poisonous. Keegan 1
writing on this subject considers this quality of comparative innocuousness
as a distinctive difference between fungi and lichens and he decides that
it proves the latter to be higher organisms from a physiological point of
view: "the colouring matters being true products of deassimilation, whereas
those of fungi are decomposition or degradation waste products of the
albuminoids akin to alkaloids."
The two outstanding exceptions to this general statement are the two
Alpine species Letharia vulpina and Cetraria pinastri. The former contains
vulpinic acid in the cortical cells, the crystals of which are lemon-yellow in
the mass. Cetraria pinastri produces pinastrinic acid in the hyphae of the
medulla and the crystals are a beautiful orange or golden yellow.
These lichens, more especially Letharia vulpina, have been used by
Northern peoples to poison wolves. Dead carcasses are stuffed with
a mixture of lichen and powdered glass and exposed in the haunts of
wolves in time of frost.
2
Henneguy , who insists on the non-poisonous
character of all lichens, asserts that the broken glass is the fatal ingredient
in the mixture, but Kobert 3
, who has proved the poisonous nature of vul-
pinic acid, says that the wounds caused by the glass render the internal
organs extremely sensitive to the action of the lichen.
Kobert, Neubert 4 and others have recorded the results of experiments
on living animals with these poisons. They find that Letharia vulpina either
effect on the mucous membrane.
powdered or in solution has an exciting
Elementary organisms treated with a solution of the lichen succumbed
more quickly than in a solution of the acid as a salt. Kobert concluded
that vulpinic acid is a poison of protoplasm.
He further tested the effect of the poison on both cold- and warm-blooded
animals. Administered as a sodium salt, 4 mg. proved fatal to frogs. The
effect on warm-blooded animals was similar. A sodium salt, whether
swallowed or administered as subcutaneous or intravenous injections, was
poisonous. Cats were the most sensitive hedgehogs the least of all the
animals that were subjected to the experiments. Volkard's 3
synthetic pre-
paration of vulpinic acid gave the same results as the solution directlyextracted
from the lichens.
1
Keegan 1905.
2
3
Henneguy 1883.
Kobert 1895.
5
See p. 228
4 Neubert 1893.