The disease may begin at one or more regions, the backs of the hands, trunk and face being favorite parts; its appearance is usually insidious, and the spots may not be especially noticeable until they are the size of a pea or larger. The patches grow slowly, are milky or dead white, smooth, non-elevated, and of rounded outline; the bordering skin is darker than normal, showing increased pigmentation. Several contiguous spots may coalesce and form a large, irregularly-shaped patch. Hair growing on the involved skin may or may not be blanched. There are no subjective symptoms. #What course does vitiligo pursue?# The course of the disease is slow, months and sometimes years elapsing before it reaches conspicuous development. It may after a time remain stationary, or, in rare instances, retrogress; as a rule, however, it is progressive. Exceptionally, the greater part, or even the whole surface may eventually be involved. #Give the etiology of vitiligo.# Disturbed innervation is thought to be influential. The disease develops often without apparent cause. Alopecia areata and morph[oe]a have been observed associated with it. [Illustration: Fig. 36. Vitiligo.] #State the pathology of vitiligo.# The disease consists, anatomically, of both a diminution and increase of the pigment--the white patch resulting from the former, and the pigmented borders from the latter. There is no textural change, the skin in other respects being normal. #From what diseases is vitiligo to be differentiated?# From morph[oe]a and from the anaesthetic patches of leprosy. #In what respects do these diseases differ from vitiligo?# In morph[oe]a there is textural change, and in leprosy both textural change and constitutional or other symptoms. #What prognosis is to be given?# It should always be guarded, the disease in almost all cases being irresponsive to treatment. #What is the treatment of vitiligo?# The general health is to be looked after, and remedies directed especially toward the nervous system to be employed. Arsenic, in small and continued doses, seems at times to have an influence; when there is lack of general tone it may be prescribed as follows:-- [Rx] Liq. potassii arsenitis, ............. f[dram]j Tinct. nucis vom., ................... f[dram]iij Elix. calisayae, ....... q. s. ad ..... f[Oz]iv. M. SIG.--f[dram]j t. d. Suprarenal-gland preparations in moderate dosage long continued has appeared in a few instances to be of some benefit. When upon exposed parts, stimulation of the patches, with the view of producing hyperaemia and consequent pigment deposit; conjoined with suitable applications to the surrounding pigmented skin, with a view to lessen the coloration (see _treatment of chloasma_), will be of aid in rendering the disease less conspicuous. Or the condition may be, in a measure, masked by staining the patches with walnut juice or similar pigment.