186 CELL INTELLIGENCE THE CAUSE OF EVOLUTION 



much more slowly acting one may be run over. If you 

 are too slow at taking the 'service' at tennis, you will miss 

 the ball. But the nervous system attends to other matters 

 than mere speed ; it cares for accuracy too. Thus at ten- 

 nis not only must I strike the ball at the right instant, but 

 at the proper spot of my racket, not the handle, not the 

 wood. The muscular adjustments necessary to bring the 

 center of the racket in contact with the flying ball are car- 

 ried out by co-ordination. A large number of muscular 

 activities have to be co-ordinated to bring about any de- 

 sired activity; many, perhaps widely separated, muscular 

 groups have to be brought into simultaneous contraction, 

 while other muscular groups require to have their activi- 

 ties restrained. All games of skill, for instance, billiards, 

 gymnastics up to trapeze displays, and tight-rope walk- 

 ing, involve this co-ordination. The nervous system is 

 the essential in co-ordination, whether it be in the baker's 

 boy balancing his bread-board on his head, or in Cinque- 

 valli balancing two billiard balls on the top of a cue on the 

 end of his nose. Supreme accuracy of muscular adjust- 

 ment it is that underlies all these different performances, 

 but in smaller degrees we all employ it, as we are 

 bound to do. We co-ordinate our muscles to step out of 

 a carriage on to the ground, to ride on horseback, to ride 

 a bicycle, to steer a motor car, to use a typewriting ma- 

 chine, and so on. 



"Besides accuracy of adjustment there is the element 

 of the precise amount of force to put into the muscles. 

 This putting forth the exact amount of force neither too 

 much or too little, means the exact or right measure (of 

 force). Thus not only must the tennis ball be struck at 

 the right instant with the right spot of the racket, but it 

 must be struck with the proper amount of force in order 

 to be returned 'within court.' 



"The nervous system as a rule learns by slow and pain- 



