(See Fish and Oil).

The Cod is found by those who have made competent research to be one of the least digestible fish, though containing but little fat. Its fibre is coarse, and woolly, but Cods' heads baked in the oven are excellent. The ancient Greeks held the Codfish (Morrhua) in high estimation, preparing it with grated cheese, vinegar, salt, and oil. Its stomach (which it is said to have the faculty of turning inside out) is mostly found quite empty, and clean, as the result of its enormous digestive power, which habit has, without doubt, a great influence on the flesh, helping to keep it healthy, and well scoured. Cods' sounds, or the swimming bladder, do not dissolve as gelatine on boiling; they are but sparingly nutritious, and more an object of fancy than useful as food. From the fresh livers of Codfish (subjected to a steam bath) is procured the highly curative Cod-liver oil, considered elsewhere in these pages (see "Oils"). Par excellence it is of the most essential service as a food, and as a medicine, in pulmonary consumption.

Underlying this scourge, which has hitherto proved so widespread, and fatal, there are now found to be special micro-organisms which die out under the modern open-air treatment, together with an abundance of generous food even to excess. Similarly an intensity of light will completely destroy the micro-organisms of erosive skin disease external to the body; but the light for safe concentration upon such diseased surfaces has to be deprived of those rays which burn (red, green, and yellow), whilst it exercises its beneficent action solely by the chemical rays (blue, violet, and ultra-violet). This grand desideratum has been made feasible by the ingenious method of Dr. Finsen, consisting of a plain glass lens, with a second lens of curved glass, between which glasses is interposed a bright blue solution of sulphate of copper, by which means the heat rays are got rid of, , Then the beam of intense cool light is concentrated on the diseased skin through a lens of quartz, which the nurse presses continually over the patch of morbid, skin under treatment. In this way the offending microbes can be constantly killed off without discomfort to the sufferer, who has only to lie still under the process for an hour a day. This practice has been well tried, and produces marvellous results of cure.

Long years back John of Gaddesden, a famous physician of his time, gained considerable renown for curing John, son of Edward the Second, who had contracted small-pox, by treating him with red light under such means as could then be contrived. He had the Prince laid in a bed with red curtains, red blankets, and a red counter-pane, giving the sick man some of the ruddy juice of pome granates to suck, and making him gargle his throat with mulberry wine of a like colour. This doctor, who died in 1561, wrote a quaint book which he called Rosa Medicinae, containing curious old receipts for treating various maladies after the same fashion.