Too long exposure to cold is destructive of living beings. Vegetables endure cold much better than animals, but even vegetable life is destroyed when the cold becomes too great. There is no vegetation at the poles or on the tops of high mountains. The effect of cold on the blood is quite marked. The reaction which follows the temporary chilling of the blood is found to increase the number both of white and blood corpuscles, and also the quantity of the coloring matter - hemoglobin. It has long been noticed that people who live in cold climates and out-of-doors for the most part have ruddy complexions, which are not found in people inhabiting warm regions. Thus a judicious use of cold is fruitful of good results.