78 



ANIMAL LOCOMOTION. 



possess many of the peculiarities of the hind legs of the sea- 

 bear, but display the movements peculiar to those of the seal. 

 In other words, the anterior extremities or flippers of the 

 walrus are moved alternately, and reciprocate, as in the sea- 

 bear ; whereas the posterior extremities are lashed from side 

 to side by a twisting, curvilinear motion, precisely as in the 

 seal. The walrus may therefore, as far as the physiology of 

 its extremities is concerned, very properly be regarded as 

 holding an intermediate position between the seals on the 

 one hand, and the sea-bears or sea-lions on the other. 



Swimming of Man. — The swimming of man is artificial in 

 its nature, and consequently does not, strictly speaking, fall 

 within the scope of the present work. I refer to it princi- 

 pally with a view to showing that it resembles in its general 

 features the swimming of animals. 



The human body is lighter than the water, a fact of con- 

 siderable practical importance, as showing that each has in 

 himself that which will prevent his being drowned, if he will 

 only breathe naturally, and desist from struggling. 



The catastrophe of drowning is usually referrible to nervous 

 agitation, and to spasmodic and ill-directed efforts in the 

 extremities. All swimmers have a vivid recollection of the 

 great difficulty experienced in keeping themselves afloat, when 

 they first resorted to aquatic exercises and amusements. In 

 especial they remember the short, vigorous, but flurried, mis- 

 directed, and consequently futile strokes which, instead of 

 enabling them to skim the surface, conducted them inevitably 

 to the bottom. Indelibly impressed too are the ineffectual 

 attempts at respiration, the gasping and puffing and the swal- 

 lowing of water, inadvertently gulped instead of air. 



In order to swim well, the operator must be perfectly calm. 

 He must, moreover, know how to apply his extremities to the 

 water with a view to propulsion. As already stated, the body 

 will float if left to itself ; the support obtained is, however, 

 greatly increased by projecting it along the surface of the 

 water. This, as all swimmers are aware, may be proved by 

 experiment. It is the same principle which prevents a thin 

 flat stone from sinking when projected with force against the 

 surface of water. A precisely similar result is obtained if the 



