_ | 1. The Use of the Muscles. | 2. Contractility of the Muscles. _ | 3. Arrangement of the Muscles. | 1. THE USE, STRUCTURE | 4. The two Kinds of Muscles. | AND ACTION OF THE | 5. The Structure of the Muscles. | MUSCLES. | 6. The Tendons for Fastening Muscles. | | 7. The Muscles and Bones as Levers. | | 8. The Effect of Big Joints. | | 9. Action of the Muscles in Walking. | |_10. Action of the Muscles in Walking. | | 2. THE MUSCULAR SENSE. | _ | 3. HYGIENE OF THE | 1. Necessity of Exercise. | MUSCLES. | 2. Time for Exercise. | |_ 3. Kinds of Exercise. | | 4. WONDERS OF THE MUSCLES. | _ | | 1. St. Vitus's Dance. | | 2. Convulstions. | | 3. Locked-jaw. |_5. DISEASES. | 4. Gout. | 5. Rheumatism. | 6. Lumbago. |_ 7. A Ganglion. FIG. 14. [Illustration] THE MUSCLES. THE USE OF THE MUSCLES.--The skeleton is the image of death. Its unsightly appearance instinctively repels us. We have seen, however, what uses it subserves in the body, and how the ugly-looking bones abound in nice contrivances and ingenious workmanship. In life, the framework is hidden by the flesh. This covering is a mass of muscles, which by their arrangement and their properties not only give form and symmetry to the body, but also produce its varied movements. In Fig. 14, we see the large exterior muscles. Beneath these are many others; while deeply hidden within are tiny, delicate ones, too small to be seen with the naked eye. There are, in all, about five hundred, each having its special use, and all working in exquisite harmony and perfection. CONTRACTILITY.--The peculiar property of the muscles is their power of contraction, whereby they decrease in length and increase in thickness. [Footnote: The maximum force of this contraction has been estimated as high as from eighty-five to one hundred and fourteen pounds per square inch.] This may be caused by an effort of the will, by cold, by a sharp blow, etc. It does not cease at death, but, in certain cold-blooded animals, a contraction of the muscles is often noticed long after the head has been cut off.