OF LOCOMOTION. 



93. It is easy to perceive that the parts which act most in the 

 leap are the legs : indeed, it is upon them that the weight to be 

 raised is most considerable. The facility and rapidity of the leap 

 are always in direct ratio to the energy of the muscles, which 

 determine the extension of the legs. It is observed that the most 

 vigorous dancers and even great walkers have the calf strongly 

 developed : indeed this part is formed of the muscles which effect 

 the extension of the leg upon the foot. 



94. Running partakes both of walking and leaping. There is 

 always a moment in running when the body is suspended in the 

 air, a circumstance which distinguishes it from rapid walking in 

 which the foot that rests behind does not leave the ground until 

 the forward one again touches it. 



95. Swimming and flying are movements analogous to those 

 of leaping, but which take place in water or in the air, fluids 

 whose resistance to a certain extent, takes the place of that of 

 the ground in the act of leaping. . 



96. When an animal is destined to live in water and to swim, 

 its members have a different form from that of those animals 

 which are organized for walking only. The limbs are then short 

 and constitute a species of paddles or oars called fins. When 

 the animal is designed to elevate himself in the atmosphere, the 

 thoracic members on the contrary are very much expanded and 

 are so arranged on each side of the body as to form a kind of 

 moveable sail or fan, fit to strike the air with force. 



In one of the following lessons, when we consider the mam- 

 malia and birds, we shall recur to the study of these organs, and 

 we shall see how the same members may constitute in different 

 animals, the instruments of prehension, of walking, of natation, 

 or of flight. 



We here conclude what we proposed to say generally, on the 

 manner in which the principal phenomena of animal life are per- 

 formed, and on the organs which serve as instruments for the 

 exercise of the faculties with which animals are endowed. 



We shall next proceed to study each of these animals in par 

 ticular, and see in what way they differ from each other 



END OF ANATOMY AND PHYSIOLOGY. 



93. What is remarkable in the legs of great dancers and walkers ? 



94. What is the mechanism of running / 



95. What are swimming and flying ? 



96. What is the character of those animals which are destined to live in 

 water? What is the character of the limbs of those animals destined to 

 ilevate themselves in the air ? 



