The foregoing throws some light on the therapeutic accomplishments of iodine preparations, when topically applied, and, to a certain extent, explains its _modus operandi_ in a physiological sense--an understanding somewhat essential from an ethical standpoint. The old theory, which would ascribe to an increase in function of the regional lymphatic glands all the agreeable therapeutic effects of local iodine applications, does not cover enough ground; it is only when we amplify this theory, with the assumption of the considerations aired in the foregoing paragraphs, that we find it possible to attain a clear understanding of the physiological action of iodine preparations applied regionally. _The Clinical Aims_ for topical therapy are to be classified as follows: 1. PROPHYLACTIC. 2. AMELIORATIVE. 3. CURATIVE. Under these three heads, we further sub-classify the actual clinical conditions, which are indicated, into the following: Under 1. Surgical preparatory technique. Under 2. Acute pathological conditions, in the corrections of which topical applications of iodine preparations are used as an adjunct to internal medication with other agents. Under 3. Chronic pathological conditions, in which one or more of various iodine preparations, locally applied, constitutes the entire treatment. This classification and sub-classification is important and essential when we endeavor to make our use of iodine conform to ethical standards; it is also very essential to the attainment of certain therapeutic ends in actual practice. 1. THE LOCAL APPLICATION OF PREPARATIONS OF IODINE IN THE SENSE OF PROPHYLACTIC AIM IN SURGERY. The exhaustive pre-operative washing and scrubbing of the integument, that veterinary practitioners applied to their surgical patients in years past, has given way almost entirely to iodine painting. Even those surgeons who still adhere to the scrubbing and washing of the parts about to be incised, complete the process with an application of iodine thereafter. An application of iodine to the skin covering the region that is about to be invaded by the knife of the surgeon, has been found much more efficacious and much more reliable than has the washing and the scrubbing with antiseptic solutions, soaps and other agents. Not only this, but it has also greatly simplified and shortened an otherwise tedious, prolonged and sloppy technique. Whereas, the surgeon formerly spent from fifteen minutes to half an hour scrubbing and washing the field of operation, he now applies a few coats of iodine tincture--a few strokes of the swab or brush--and it is done.