Framework 57 



And these muscles, instead of being limited in their action 

 to their immediate surroundings, have developed a system 

 of long, non-muscular tendons by means of which their force 

 can be brought into play at points remote from their own 

 location. When you lift your heels off the ground and stand 

 on the balls of your feet, it is the muscles well up in the 

 calves of your legs which are doing the work, as you can 

 determine by feeling them. Nothing like this takes place in 

 the fish. 



Furthermore, in us, every muscle is different from every 

 other muscle, except for its counterpart on the other side of 

 the body. Efficiency and power have been achieved by a high 

 degree of specialization. At the time that the fish was being 

 designed, this idea had no currency, and the only way to 

 achieve greater power was to keep on adding more of the 

 same thing. The fish is confined to a few elements, used 

 over and over again — the muscle segment, the fin-ray or 

 spine, the vertebra — whereas we have many elements, each 

 designed for a special purpose, and each used only once. 

 Some units are, it is true, repeated, like the fingers and the 

 ribs, but they differ from each other, and even our vertebrae 

 change their shape from one part of the backbone to another. 

 Progress has consisted in reduction of numbers and in 

 specialization. 



The great mass of potential motive force being located 

 in the body, and not in the fins, how does the fish move? 

 Mainly by body strokes, alternately to the right and left. 

 The muscle segments contract in succession, first along one 

 side and then along the other, and the fish pushes against 

 the water first on one side and then on the other, somewhat 

 in the way a skater pushes against the ice. No one who has 

 ever watched a fish move at full speed will forget that vio- 

 lent side-to-side swinging of the body, culminating in the 

 wide sweep of the tail fin. It is in contrast to the apparent 



