MUSCLE, BRAIN, AND NERVES 21 



Although every bone in the body serves some special pur- 

 pose, persons are frequently bereft of limbs by accident, 

 and even some of the bones of the head and trunk, because 

 disease demands their sacrifice. But if their loss incon- 

 venience life it does not destroy it, nor even of necessity 

 shorten it. The removal of the smallest bone of the 

 vertebral column, however, entails certain death, the 

 advance of which all the medical skill in the world is 

 powerless to check. 



Muscles. The bones of the body are clothed with 

 flesh. The red lean flesh is muscle. A mass of red flesh 

 really consists of bundles of tissues capable of moving 

 or sliding about. These movable bundles are the muscles, 

 terminating in tough, leather-like cords, called tendons, 

 which bind the muscle to the bone an elastic binding 

 which allows at will the freest extension and contraction of 

 the bones thus jointed together. Wherever is required the 

 greatest power of movement, there are the largest and 

 strongest muscles. Compare the mass of flesh around the 

 thigh, the calf, and the arms with the thin covering of the 

 skull ; but the bones of the skull do not move and thus have 

 no need of muscle. 



Brain and Nerves. The skull is a hollow, bony box 

 containing the brain, which consists of a white delicate 

 material very different from the solid flesh of the muscles. 

 The cavity of the skull is not only filled up with this sub- 

 stance, but it extends in a narrow, rod-like mass right down 

 the tunnel or canal formed by the hollow ring of each 

 vertebral bone. Running out from the brain into the head 

 and from the spinal cord into the body are delicate white 

 threads that divide into innumerable branches and so spread 

 throughout the flesh. These are the nerves, the telegraph 

 wires of the body. It is the brain and nerves that enable 

 us to see, hear, smell, taste, and touch. Upon the brain 

 depend our will, intellect, and memory, our affections and 

 every emotion of which the human mind is capable. The 

 telegraphic nature of the nerves is easy of illustration. If 

 in the darkness one step upon some slippery substance, in 

 a flash the nerves communicate the presence of danger to 

 the brain ; and with equal celerity the brain calls upon the 



