I am convinced that disease is not the only thing, that the cellular atmosphere of the organs serves to propagate, but it is also the means of communicating medicinal effects. Why is a blister often useless that is applied to a remote part in rheumatism, whilst one placed upon the skin that covers the muscle or the fibrous organ that is the seat of the disease, frequently produces a sudden effect? Why has a cataplasm applied to the scrotum oftentimes an influence upon a diseased testicle, though between the cutaneous organ and this gland there is no relation of vitality? Why do several other medicines applied also to the skin, produce an action upon the subjacent parts? The cellular texture is certainly the means of communication, as in the different applications made to the mucous membranes. A gargle is advantageous in inflammations of the tonsils; an emollient enema diminishes that of the peritoneum, &c.: now these means are not applied directly to the affected organ; their effects are transmitted by the sub-mucous texture. However, the advantages of these applications have been much exaggerated, both when applied to the cutaneous and mucous surfaces, with a view of acting upon organs of different vitality, and which are subjacent to these surfaces. Practice too often proves that they may be excited, and irritated in a certain manner, without the contiguous organ being affected, because their life and that of the organ has no resemblance or correspondence, the one is indifferent to the affections of the other, though the parts are contiguous. Who does not know, how little effect emollients, discutients, &c. have, upon tumours of the breast, of the glands of the groin, axilla, &c.? and that they are as often cured without our applications as they are with? Formerly, when a tumour appeared projecting under the skin, if it was seated in the abdominal viscera, and consequently separated from the cutaneous organ, by many others of a different and even opposite vitality, they covered it with a poultice. All modern surgeons admit the inutility of applications made in this way, and now confine them to the most sub-cutaneous organs. Perhaps hereafter we shall be sufficiently acquainted with the degree of vitality of each organ, to know when the cellular texture can be the means of communication of medicinal effects, between two contiguous organs, with different structure and properties, and when it is a barrier which stops the communication of these effects. At present we go almost always groping in the dark. Frequently a cutaneous application acts by sympathy upon very distant organs, whilst it has no effect upon neighbouring ones, with which it has no relation; for example, a bath will check a spasmodic vomiting, while it will have no sensible effect in diminishing pain which has its immediate seat in the sub-cutaneous organs.