The medical student has so many subjects for his consideration, that it is not desirable he should have a greater number of vegetables to consult than are necessary. And we cannot help lamenting the difficulty he has to struggle with in consequence of the great difference of names which the Pharmacopoeias of the present day exhibit. The London, Edinburgh, and Dublin, in many instances, enforce the necessity of learning a different term in each for the same thing, and none of which are called by the same they were twenty years ago. Surely it would be the means of forwarding the knowledge of drugs, if each could be distinguished by one general term. The candidate for medical knowledge, however, is not the only one who has at times to regret this confusion of names. The Linnaean system is an easy and delightful path to the knowledge of plants; but, like all other human structures, it has its imperfections, and some of which have been modified by judicious alterations. Yet the teachers of this science, as well as the students, have often to deprecate the unnecessary change in names which has been made by many writers, though., in many cases, no more reason appears for it than there generally would be to change Christian and surnames of persons. In the following section, I shall enumerate and describe those plants which are contained in the lists of the three colleges; and afterwards a separate list of those which, although they have been expunged, are still sometimes used by medical men. I shall also endeavour to give such descriptions as are concise, at the same time sufficient for general knowledge, and for which reason I have taken Lewis's Materia Medica for my text, unless where improvements have been made in certain subjects I have consulted more modern authorities. It should be observed, that writers on medical plants, with few exceptions, have copied from one another: or with a little alteration as to words only. And as some vegetables, from their affinitiy, may be confounded with others, whereby those possessing medical qualities may be substituted for others having none, or even poisonous ones, I shall in some instances enumerate a list of similar plants, which, with attention to their botanical characters, it is hoped will prevent those dangerous errors we have lately witnessed. As it is our business, in demonstrating plants, to guard the student against such confusion, it will be proper that specimens of such as come under this head be preserved, as a work for reference and contrast wherever doubts may arise. 158. ACONITUM Napellus. COMMON BLUE MONKSHOOD. The Leaves. L. E.--Every part of the fresh plant is strongly poisonous, but the root is unquestionably the most powerful, and when chewed at first imparts a slight sensation of acrimony, and a pungent heat of the lips, gums, palate and fauces, which is succeeded by a general tremor and sensation of chilliness.