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"[Plin. Nat. 25.98.] - THE FIRST KIND OF CAPNOS, KNOWN ALSO AS CHICKEN’S FOOT: ONE REMEDY.
The first kind of capnos, known also as “chicken’s foot,” is found growing on walls and hedges: it has very thin, straggling branches, with a purple blossom. It is used in a green state, and the juice of it disperses films upon the eyes; hence it is that it is employed as an ingredient in medicinal compositions for the eyes.”
(The Natural History. Pliny the Elder. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855.)