IJ2 Human Physiology. 



does, what is the force that determines and governs the 

 secretion? 



The power of muscular contraction is very great. Nearly 

 all the muscles act at a great disadvantage. To raise twenty 

 pounds with my hand, bending the elbow, the flexor muscles of 

 the fore arm attached to the lever so near the fulcrum and so 

 far from the weight, must exert a force of about 200 Ibs. To 

 hold a heavy weight out at arm's length, the muscles of the 

 shoulder must contract with an immense force. Examine these 

 muscles you will find bits at the butcher's and you see 

 only a flabby mass of fibres, three-fourths water, with fat and 

 membrane. The thickest muscle in the human body, the 

 gluteus maximus, when perfectly dried, is like a sheet of paper. 

 The whole force is in the attraction of microscopic disks for 

 each other, excited by nervous action. That the intensity of 

 this force is in proportion to the nervous or cerebral excitement 

 is shown in the extraordinary strength of maniacs, or men act- 

 ing under sudden excitement. In some cases of disease also, 

 the spasmodic muscular action is long-continued and frightful. 

 In these cases, it seems out of all proportion to the food eaten, 

 or the bodily condition. The mind controls the body in ways 

 utterly unaccountable by the chemical and materialistic physio- 

 logists. The force and rapidity of muscular action in insects 

 has been noticed in Part II. A fly can keep up with a race- 

 horse, but his muscular contractions must be thousands of times 

 more rapid. 



