_Toxic Principle._ Poisoning by Henbane is due to the alkaloids _Hyoscyamine_ (C_{17}H_{23}NO_{3}) and the closely related _Hyoscine_, or _Scopolamine_ (C_{17}H_{21}O_{4}N). The glucoside _Hyoscypicrin_ is also found in Henbane. The poisonous property is not eradicated by drying or boiling. The leaves of Henbane grown in Europe contain from 0·04 to 0·08 per cent. of total alkaloid, and the seeds 0·06 to 0·10 per cent. (_Bul. Imp. Inst._, 1911). _Symptoms._ Henbane is an anodyne, and hypnotic. The symptoms resemble those caused by _Atropa Belladonna_ (p. 58). The important differences (Cornevin) are that there is here abundant salivation and no dryness of the mouth as in _Atropa_. There is dilatation of the pupils; and mydriasis, which is dissipated more slowly than in Belladonna poisoning. Further differences in the action of the two poisons are given by Winslow (_via_ Pammel): The tetanic stage succeeding spinal paralysis observed in Atropine poisoning does not ensue with Hyoscine. The latter alkaloid slightly depresses and slows the heart and does not paralyse the vagus terminations, nor depress the motor and sensory nerves or muscles. The circulation is but slightly influenced, and vasomotor depression only occurs in the later stage of lethal poisoning. Death occurs from paralysis of the respiratory centres. Poisoning in animals is exhibited by loss of muscular power, slowing and failure of respiration, stupor, and asphyxia. The pulse may be infrequent, the pupils are dilated, and the skin is moist rather than dry. The following symptoms in animals are given by Welsby: Nervo-muscular exaltation, eyelids and irides much dilated, eyes amaurotic and very bright, pulse full, temperature normal, respiration difficult and hurried, profuse salivation, muscles of neck and extremities in a state of tetanic rigidity, considerable abdominal distension, stercoraceous and renal emunctories entirely suspended, death. In a _cow_ there was observed, two hours after eating, dilatation of pupils, the conjunctivæ were injected, and the carotids beat violently. There were general convulsions, loud respiration, salivation, and purgation. According to Pott the milk of affected cows is of an unpleasant taste. REFERENCES. 4, 16, 39, 57, 68, 73, 81, 128, 141, 151, 157, 161, 190, 203, 205, 213, 257.