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CHAPTER III. 



LOCOMOTION. PASSIVE AND ACTIVE ORGANS OF LOCOMOTION. FI- 

 BROUS TISSUE, WHITE AND YELLOW. AREOLAR TISSUE. ADIPOSE 

 TISSUE AND FAT. 



LOCOMOTION is that function by which an animal is able to 

 transport itself from place to place. It is enjoyed exclusively by 

 animals; there being nothing analogous to it in the vegetable 

 kingdom. 



But even, among animals, there are exceptions to the existence 

 of this function. Many of them are fixed in their places through- 

 out their lives; others enjoy the power of locomotion for a short 

 period, but subsequently become fixed; others, again, begin life 

 fixed to one place, and are at length set free. 



The power of maintaining the body in certain positions, must be 

 included in the faculty of locomotion, for the organs that are used 

 for one, are also employed for the other ; and, the more difficult it be 

 to accomplish the former, the more complicated will be the mecha- 

 nism of the locomotive acts. In a large quadruped, the horse, for 

 example, standing is effected with a trifling expenditure of mus- 

 cular force, because the animal's body is maintained on four pillars 

 of support, which resist the attraction of gravity acting upon it. 

 Man has to maintain the erect attitude, and to counteract by mus- 

 cular action the tendency of his body to gravitate forwards. The 

 mechanical adjustments of his frame are less favourable to preserve 

 the standing posture than in the four-footed animal. Hence, in 

 man, the mechanism of locomotion is more complicated, both as 

 regards the power of preserving certain attitudes, and that of 

 moving from one place to another. 



The organs employed in locomotion are of two kinds, the passive, 

 and the active. The former consist of all those textures which form 

 the skeleton, and by which its segments are united. The latter are 

 the muscles, to which the nerves convey the mandates of the will. 

 It will be necessary to examine in detail the following textures 

 among the passive organs of locomotion: 1. Fibrous tissue, as 

 binding together the various segments of the skeleton, and connect - 



F 2 



