The secondary and lasting effect, however (in accordance with the Law of Action and Reaction), is that the blood recedes into the interior of the body and leaves the skin in a bloodless and enervated condition subject to chills and predisposed to "catching cold." On the other hand, the first, transient effect of cold-water applications upon the body as a whole or any particular part is to chill the surface and send the blood scurrying inward, leaving the skin in a chilled, bloodless condition. This lack of blood and sensation of cold are at once telegraphed over the afferent nerves to headquarters in the brain, and from there the command goes forth to the nerve centers regulating the circulation: "Send blood into the surface!" As a result, the circulation is stirred up and accelerated throughout the system and the blood rushes with force into the depleted skin, flushing the surface of the body with warm, red blood and restoring to it the rosy color of health. This is the secondary effect. In other words, the well-applied cold-water treatment is followed by a good reaction and this is accompanied by many permanent beneficial results. The drawing and eliminating primary effect of hot applications, of sweat baths, etc., is at best only temporary, lasting only a few minutes and is always followed by a weakening reaction, while the drawing and eliminating action of the cold-water applications, being the secondary, lasting effect, exerts an enduring, invigorating and tonic influence upon the skin which enables it to throw off morbid matter not merely for ten or fifteen minutes, as in the sweat bath under the infiuence of excessive heat, but continually, by day and night. The Danger of Prolonged or Excessively Cold Applications As we have pointed out in the chapter dealing with water treatment in acute diseases, only water at ordinary temperature, as it comes from well or faucet, should be used in hydropathic applications. It is positively dangerous to apply ice bags to an inflamed organ or to use icy water for packs and ablutions in febrile conditions. Likewise, ice or icy water should not be used in the hydropathic treatment of chronic diseases. Excessive cold is as suppressive in its effects upon the organism as are poisonous antiseptics or antifever medicines. The baths, sprays, douches, etc., should not be kept up too long. The duration of the cold-water applications must be regulated by the individual conditions of the patient and by his powers of reaction; but it should be borne in mind that it is the short, quick application that produces the stimulating, electromagnetic effects upon the system. In the following pages are described some of the baths and other cold-water applications that are especially adapted to the treatment of chronic diseases. How to Keep the Feet Warm