The Art of Living in Australia: Together with Three Hundred Australian Cookery Recipes and Accessory Kitchen Information by Mrs. H. Wicken

it is in action more blood flows through it, hence we see that one of the beneficial effects of exercise is to stimulate the circulation through the muscular system. It has also been ascertained by experiments, that the venous blood which comes from a muscle in action is darker in colour than that from a muscle in repose. When the circulation is quickened by movement, and the blood stream hastened, the vigour of the body is increased, because the used up material is all the quicker taken away, and a freshly created supply of nutrition brought to every part. The rate of breathing is accelerated whenever the body is engaged in muscular exertion, and with this quickened breathing there is an increased amount of oxygen drawn in, and an increased amount of carbonic acid gas and water exhaled by the breath. The oxygen which is absorbed from the air into the blood is stored in the red corpuscles of the latter, by which it is carried to every part of the body. The venous blood which returns from every portion of the system comes back as a dark crimson, instead of being bright scarlet like the arterial blood. It contains carbonic acid, and returns it to the lungs, where it is exhaled by the breath. The oxygen is necessary to existence, while the carbonic acid is injurious. The effect of exercise, then, in any form, is thus to distribute healthy blood more rapidly through the system, while it removes the injurious matters quite as speedily. The effect of active exercise on the heart, as it is well known, is to make it beat faster; by this the blood is driven through the body at a quicker rate than usual. Sometimes, when the effort is unusually severe, there is a disturbance of the regular balance between the heart and the lungs. There is thus produced an irregular or unequal action of the former, causing what is known as "loss of wind," which is, however, soon restored by resting. There is an excessive flow of blood to the surface of the body,