“3 The incidence was lessened by: (a) methysergide , methergoline, MA 1420, p‐chlorophenylalanine and p‐chloroamphetamine; (b) dopamine, noradrenaline, l‐DOPA, amphetamine and apomorphine; (c) hyoscine and nicotine; and (d) adenosine triphosphate, dibutyryl cyclic adenosine‐3′,5′‐monophosphate (db cyclic AMP) and prostaglandins E1 and E2.”