It has always been a matter of individual speculation and dispute as to the juice of what plant Shakespeare alludes to here as the “cursed hebenon”. The meaning of the word hebenon is ebony-coloured, or black, so that it might apply to any dark liquid. Most writers and commentators seem to be of opinion that henbane is alluded to, but judging from the rapid effect of the liquid, it would appear that some more powerful poison is intended. The juice of henbane is not a powerful poison, and it is but a feeble narcotic whose effects are mainly sedative and soothing. It acts also as a neurotic, affecting the brain and producing delirium. It will be seen that there is little similitude between the actual effect of henbane and that of the poison described by the poet. Others think it more probable that hemlock, an ancient poison of the Greeks, is intended. Its action is much more rapid and powerful, the spinal cord being chiefly affected, and paralysis caused, ending in death. The drug is a powerful narcotic and anodyne, and is also a paralysant. It was well known to the apothecaries of Shakespeare’s day, its poisonous properties having been observed from very early times. It should be taken into account, that as a matter of fact the pouring of any poisonous liquid of vegetable origin into the ear would have little or no immediate effect; and unless the tympanum had been ruptured it would be almost impossible for it to be absorbed into the system and at once prove fatal.
Paris says: “Might not the juice of cursed hebenon by which, according to Shakespeare, the King of Denmark was poisoned, have been the essential oil of tobacco?” In the first place, the learned commentator Dr. Grey observes, that the word here used—hebenon—was more probably designated by a metathesis, either of the poet or transcriber, for henebon, i.e., henbane. Now, it appears from Gerade, the “tobaco” was commonly called henbane of Peru—Hyoscyamus Peruvianus; and when we consider how high the public prejudice ran against this herb in the reign of James, it seems not unlikely that Shakespeare should have selected it as an agent of extraordinary malignity. No preparation of hyoscyamus with which we are acquainted would produce death by application to the ear, whereas the essential oil of tobacco might possibly have such an effect.
The term “distilment,” says Stevens, “is calculated to support this conjecture. Surely the expression signifies that the preparation was the result of a distillation.” It is a singular fact that the essential oil of tobacco differs considerably in its physiological action from an infusion made from the leaves, the former affecting the brain, and the latter the heart.[10]
Ellacombe states: “Before, and in the time of Shakespeare, other writers had spoken of the narcotic and poisonous effects of heben, hebenon, or hebona.”
Spenser says:—
“Faire Venus sonne,...
Lay now thy deadly heben bow apart”.
Gower and Marlowe also wrote of the juice of hebon. It may be taken for granted that all these authors allude to the same tree.
Nicholson and Harrison, after a very exhaustive investigation of the subject, agree that the true reading is hebona, and that hebona is the yew. Their main arguments are based on the following three facts:—
1. That in nearly all the northern nations the name of the yew is more or less like heben.
2. That all the effects attributed by Shakespeare to the action of hebona are described by different medical writers as arising from yew poisoning.