The systematic consideration of .skin diseases from the die-tetic standpoint - or indeed from any other general standpoint of etiology and pathology or treatment - is rendered difficult partly by the fact that the nomenclature does not consistently follow either etiology, morbid anatomy or superficial appearances, but all three, so that the same term may include processes of very different nature while essentially the same pathogenic disturbance may receive different terms according to the exact form of lesion produced. Moreover, the matter has never been thoroughly studied by experts in both lines.

As a general principle, any chronic skin lesion not due to systemic or local infection, including infection with animal parasites, or due to obvious toxic, mechanic or thermic cause, is probably a manifestation of some general chemic disturbance. This may be directly due to toxins introduced with or forming a con-stituent part of food (and here many acute skin lesions may be included), or the disturbance may be of a general metabolic nature but due ultimately to insufficient or excessive food or drink or to secondary introduction of fermentative products on account of digestive faults, and hence more or less amenable to dietetic prophylaxis and treatment.

Erythema and urticaria are really different grades of the same process and are frequently caused by idiosyncratic reactions to various extrinsic causes, including foods. Why such a cause should have a toxic action on one person and not another is not explained. That it is not simply due to differences of susceptibility to definite toxic agents, is probable from the very minute quantities that cause symptoms in some individuals and the very large quantities that may be taken with impunity by the great majority of individuals. The foods most frequently causing erythema or urticaria are shell fish of any kind, Crustacea rather than molluscs, and strawberries. Fish, pork, mushrooms, cheese and other fruits than strawberries come next in general order of frequency and. as a rule, ordinary meats and vegetables, rarely produce these conditions. Preserved foods and especially such mixtures as hash, mince meat etc., are rather apt to produce these conditions, probably, on account of toxins due to putrefaction. The only special dietetic treatment is avoidance of the cause, when established by individual experience.

Acne is especially liable to occur at puberty, doubtless partly on account of the general susceptibility of the organism at this time, but also on account of the tendency to nutritive disorders and dietetic errors. Buckwheat and to a less degree, oatmeal, are especially liable to cause acne; otherwise it is due, so far as dietetic causes are concerned, to foods rich in fat and, to a less degree, those rich in sugar whether naturally or by processes of preparation and cooking. Thus, doughnuts, fried foods, sausage, cheese, excess of cream, pastry, nuts, candy are especially likely to be incriminated. However, the standard ration of proper fatty, starchy and saccharine foods must usually be maintained.

In addition to avoiding the special causes of acne, it is usually necessary, even when the acne is chronic and not directly traceable to dietetic errors, to regulate the diet so as to conform pretty closely to the physiologic standard, and with regard to digestive and other disturbances, such as constipation, hypochlorhydria and many other functional and organic conditions.

Generally speaking, the best complexions and greatest freedom from skin diseases, are found in those who abstain from tea, coffee and alcoholic drinks, who use water freely but not exces-sively, who avoid rich, greasy and excessively sweet foods, and whose diet is well balanced and derived principally from cereals and fruits.

Eczema, and asthma are quite closely connected in heredity and pathogenesis with so-called lithacmic conditions, including gout. While excessive indulgence in sugar, starch or fat may precipitate attacks, the common cause seems to be excess of purins and possibly also of protein. Hence, the diet should be mainly vegetarian, not excessive. Free movements of the bowels and action of the kidneys should be maintained by the diet as discussed under Lithaemia. There even seems to be a "poor man's" eczema corresponding to "poor man's" gout and requiring a more abundant diet.

Eczema in nurslings is often due to dietetic errors on the part of the mother, which may or may not show in her own skin. Eczema in young children is, on the whole, more likely to be due to excesses in sugar, fats, and greasy foods, precocious tea, coffee and beer drinking, than to the typic meaty and purin-containing diet.

Various forms of dermatitis, psoriasis etc., are due to improper diet and are relieved by a diet consisting mainly of milk and cereals, with fruits not too rich in acid nor used in excessive amounts.

Rosacea, often classified with acne, consists of a telangiectasis and is due largely to alcoholism but also to excessive tea drinking, overeating and dietetic errors generally.

Furunculosis may be simply an intensification of acne and due to the same general causes, or it may indicate diabetes, tuberculosis, syphilis etc., for which proper dietetic regimen should be instituted, or it may be considered as a localized sepsis, due to inadequate or badly balanced dietaries so that the resistance of the body to septic germs is diminished.

Pruritus is commonly discussed as a neurosis but it is frequently due to lithaemia and the sudden, local occurrence of itching may even be taken to represent a direct deposit of urates in a nerve terminal. In many cases, it is associated with or actually due to vascular lesions, hepatic sclerosis, renal degeneration and other processes of a fibroid nature. While it is advisable to discontinue tobacco, alcohol, tea and coffee, condiments, and rich foods of various kinds, such direct dietetic methods are likely to fail. Particular care should be taken to avoid an exclusive milk or other inadequate diet, especially in winter, when the exposure to cold with lessened resistance may produce more serious results than the original trouble. Pruritus should be regarded as the symptomatic expression either of a general dyscrasia or of some local disease interfering with metabolism, for example, incipient nephritis or hepatic sclerosis, and the diet should be regulated according to the underlying cause and not by any rule of thumb. St el wagon mentions, as dietetic causes of skin diseases:

1. Idiosyncrasy;

2. Direct local action about the lips, of acrid, acid and spicy and excessively hot or cold articles;

3 Nervous excitement or depression by tea, coffee, tobacco, alcohol etc.;

4 Irrational mixtures, as oatmeal or buckwheat with butter, syrup etc., acid fruits with milk or cream, or pickles with milk at same meal;

5. Overfeeding causes eczema, especially in infants;

6. Toxic changes in foods due to decomposition or to prolonged preservation without obvious decomposition;

7. Chemic food preservatives.