of semicircular incisions are made in the capsule of the poppy, and the juice which exudes is carefully gathered. This juice, on being dried in the sun, becomes of a dark color, thickens, and forms a brown, firm paste: this is opium. Laudanum is a solution of opium in alcohol and water. Both opium and laudanum are to be regarded as a mixture of several similar but not identical substances. Since the time of Derosne (1804) and Robiquet (1817), who first isolated narcotine and morphine, chemists have very carefully investigated the different chemical compounds occurring in opium. Thus they have discovered codeine, narceine, thebaäine, papaverine, and other substances, all of them bases, i. e., bodies that unite with acids to form crystallizable salts.
These bases do not all affect in the same way the organic functions. Thus, narcotine possesses very little or no soporific power: two grammes of it can be injected without perceptible effect, while a centigramme of morphine is quite sufficient to produce therapeutic and physiological results. Thebäine does not cause sleep, and in animals produces convulsions like those caused by strychnine, while morphine in the same dose produces deep comatose sleep. Another curious thing about these opium alkaloids is, that they do not act alike on man and animals, as has been demonstrated by Claude Bernard. Man is specially sensitive to the action of morphine, while thebäine is almost without effect upon his nervous system: animals, on the other hand, feel the effects of morphine only when it is given in large doses, while thebäine is for them a violent poison. So, too, with belladonna, and atropine, its active principle, they are a deadly poison for man, but almost without effect on rabbits: the dose of atropine that would suffice to kill ten men would hardly be enough to kill one rabbit. The difference is not so great with respect to morphine, yet morphine specially affects man; hence in this article we will consider only this one opium alkaloid.
When, in "Le Malade imaginaire," honest Argan is asked why opium causes sleep, his artless reply is, "Quia habet proprietatem dormitivam." Nowadays we are not content with this kind of explanation, and some authors have sought for the "dormitive property" of opium in the state of the cerebral circulation; and, though the true cause has not yet been certainly established, still it is something that research has been made.
It is not yet positively decided whether opium produces anæmia or whether it produces congestion of the brain; indeed, we know little more than did Argan, namely, that it sets one asleep. This sleep, however, is in some respects different from ordinary sleep. From thirty to sixty minutes after taking opium one feels a slight excitation; there is a general feeling of buoyancy and contentment, soon followed by drowsiness and a state of reverie rather than of dreaming. There is a pleasurable feeling of abandon, and an agreeable
