Dr. Darwin has ingeniously shown the analogy between the functions of the leaves of plants, and the lungs of animals. If this be admitted, it will not be difficult to account for the action of salt upon leaves. This substance, when taken into the stomach, proves not merely innocuous, but wholesome; but when accidentally introduced into the lungs, irritation, inflammation, and death are the consequences. So with plants--when admitted into them in combination with their juices, it may be harmless; but when applied to the lungs or leaves, death ensues. 4. I shall devote the remainder of this paper to a few concise observations on the effects of salt, and a saline atmosphere, upon _animal_ life. Upon the more imperfect animals, such as slugs, worms, toads, &c. it is well known that salt proves speedily destructive of life. It is not my intention to attempt an explanation of this singular fact. But it is remarkable that it should not have been turned to better account in the treatment of those worms, which infest the human body. Although used for that purpose by the common people in Ireland as well as in this country, I believe it has not, until very lately, claimed the attention of the profession, as an anthelmintick. A late English journal[66] contains a notice of some cases which satisfactorily prove its efficacy, when administered with this intention. This fact, in addition to numerous others, strikingly illustrates the advantages which the healing art might derive from a careful observation of the phenomena daily developed by the collateral sciences. In cases of _hæmoptysis_ and _hæmatemesis_, common salt has been used with decided success. The public is indebted to Dr. Rush, for the introduction of this remedy into general practice. Dr. Hosack informs me, that he has found sea air extremely salutary in _remittent fever_, _cholera infantum_, and _dyspepsia_. Among the deleterious effects caused by a _saline atmosphere_, may be mentioned the _ophthalmia_ of Egypt. This disease is so common there, "that out of a hundred persons," says Volney, "I have met while walking the streets of Cairo, twenty have been quite blind, ten wanting an eye, and twenty others have had their eyes red, purulent, or blemished."[67] Throughout the Delta, and at Cairo, this complaint is more prevalent than in any other part of Egypt. In Syria it is also common, although less so than in Egypt, but it is only met with on the _sea-coast_. The reasoning of Volney on this subject, is decisive of the position, that the prevalence of this complaint, in these regions, is owing to their proximity to the ocean. In confirmation, he states that he has himself experienced the irritating effects of the air of the Delta upon the organ of vision.[68]