THE INFLUENCE OF SOIL may be exemplified by many well known facts; thus, strongly smelling plants lose their odour in a sandy soil, and do not again recover it by transplantation into a richer one; a fact upon which Rozier founded his proposal for the improvement of Rape oil; so again, no management could induce the _Ricotia Ægyptiaca_ to flower, until Linnæus suggested the expediency of mixing clay with the earth in the pot; _Assafœtida_ is one of those plants that vary much according to station and soil, not only in the shape of the leaves, but in the peculiar nauseous quality of the juice which impregnates them, and Dr. Woodville states that it is frequently so modified that the leaves are eaten by goats; Gmelin informs us, on the authority of Steller, that the effects of the _Rhododendron_ have been found to vary materially according to the “_solum natale_;” for example, that produced in a certain spot has proved uniformly _narcotic_, that in another, _cathartic_, while a sense of suffocation has been the only symptom occasioned by a third. Rhubarb, as grown in England, will differ greatly in its purgative qualities, according to the soil in which it may have been cultivated; that produced in a dry gravel being more efficacious than that which is reared in a clayey one. Dr. Carter, in his account of the “_Principal Hospitals of France, Italy, and Switzerland_,” tells us that at Nice, the _Digitalis_ is commonly given in doses of a scruple in powder, or in that of half an ounce of the infusion made according to the London Pharmacopœia, every hour, and without any sensible effect; this fact he explains by stating that the _Digitalis_, in the neighbourhood of Nice, is much smaller, and is probably less powerful than the same plant as it grows in England.