Emetine, as separated by Pelletier and Magendie, is powerfully emetic.

Morphium, obtained by Serturner, is a very strong narcotic.

The foregoing are some of the examples, which the present state of Chemistry allows us to observe of affinity between chemical and medicinal characters. With a few exceptions they will be found to be strictly true. Yet the analysis of vegetables is at present but imperfectly known, and an extended investigation is continually bringing new principles to light. We can hardly expect that the business of generalization should be attempted with complete success, until the constituent factsare better understood. From what we already know, however, it is not chimerical to predict, that if the chemistry of vegetables were as perfectly known in all its parts, as in those which we have detailed; their medicinal properties might be inferred, with at least as great certainty, as that which now attends most inferences in the conjectural science of medicine.

In regard to the botanical affinities of plants, as affording evidence of their medicinal powers, much has been said and written. Petiver, Hoffman, Linnæus, Hasselquist, and recently the learned Professor Decandolle have bestowed much

investigation on this subject. It is regarded as a desideratum by all, and as the consummation of botanical science by many, that plants should be so arranged, as that their assemblages should agree, not only in external forms, but in internal qualities and operative powers. Certain general agreements of this kind evidently prevail throughout nature; yet they are so varied, and subject to so many exceptions, that it is difficult to establish them by general scientific descriptions, and when they are rendered too minute they seem to lose much of their importance. It is perhaps as easy to know the properties of plants from their external habit, as to understand the characters of mankind from their physiognomy. Accurate observers know more than they can communicate the means of knowing to others, yet the most accurate are liable to be mistaken. Many vegetables of the closest affinity and resemblance, even species of the same genus, differ wholly from each other in their effects. Witness the species of Cucumis, Convolvulus, and Solanum, some of which are salutary, and others highly deleteriNevertheless there are many general truths, or at least general probabilities, by which every one would be influenced, and which have so much importance, that they will never be forgotten.

ous.

No botanist, even if in danger of starving in a wilderness, would indulge his hunger on a root or fruit taken from an unknown plant of the natural order Lurida, of the Multisiliquæ, or the umbelliferous aquatics. not feel a moment's hesitation in regard to any of the Gramina, the fruit of the Pomacea, and several other natural families of plants, which are known to be uniformly innocent in their effects.

On the contrary, he would

The sensible properties of plants afford another clue to their influence on the human system. It is true, that observations derived from this source will not serve us in forming very minute distinctions. They are, however, almost always adequate in vegetable productions, to enable us to distinguish what is innocent and salubrious, from what is noxious and virulent. The brute creation depend wholly upon the powers of sense in selecting their food, and this reliance does not often betray them. In regard to mankind it almost uniformly happens, that what is sweet, delicious, or aromatic, proves nutritive or salutary; while on the other hand, vegetable poisons are nauseous, acrid, and disgusting. It has been observed, that it would have been a sort of treachery in nature to have made it otherwise. Considering the universal dissemination of poisonous plants, and the

number of them, which frequent the vicinity of human habitations, this arrangement of Providence, by making ungrateful what is dangerous, has furnished almost the only safeguard from harm, to the inexperienced and unwary.

These remarks have been offered on account of an impression which many persons entertain, that collateral evidences of the characters of plants are worthless and undeserving of attention. Even if the community were composed exclusively of physicians, such an opinion could not be wholly correct. Every one may be called on to form hasty decisions on subjects where his experience is deficient, and where an acquaintance with auxiliary facts might lead him to a correct issue. It is not only curious and instructive to perceive the harmonies of nature, but to every inquirer among her works it must be practically useful. It can no where be more useful, or more deserving of study, than in a new country, where the face of nature presents an ungathered harvest, and where every clue to useful discovery derives importance from its influence and tendency.