Abstract
The cock's comb test has become a popular method of determining the activity of ergot preparations. It was introduced because gangrene frequently occurred in epidemics of ergot poisoning, and because bluing of the cock's comb was believed to be due to arterial constriction. This view was supported by von Recklinghausen's interpretation of the microscopical examination of the comb in chronic ergot poisoning of cocks. We were impressed by the fact that in ergot poisoning often the only pathological feature was venous dilatation and we believe that venous dilatation is probably the real cause of the bluing of the comb. It is admitted that the intravenous injection of epinephrin causes a rise in blood pressure, mainly from vaso-constriction and we have found that it will blue the cock's comb, but the bluing only comes on as the blood pressure falls and persists for an hour or two; in other words it occurs at a time when arterial-constriction has subsided. Large doses of paraldehyde given per os, or the inhalation of amyl nitrite, will also cause bluing of the comb.
On subcutaneous injection neither adrenalin nor p. oxyphenylethylamine caused this bluing. Dale claims that much of the activity of ergot preparations is due to p. oxyphenylethylamine. Now while the subcutaneous injection of 25 mg. of p. oxyphenylethylamine caused marked symptoms in cocks, there was no bluing, hence one would argue that the subcutaneous injection of ergot into cocks cannot be considered a quantitative method for testing ergot. Oncometric studies of the cock's comb during acute ergot poisoning are now being made.
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