196 



SENSORY AND MOTOR NERVES. 



Each nerve is made up 

 of a number of very slen 

 der threads, named ner&e- 

 fibres, which run side by 

 side in it like the threads 

 in a skein .of silk. As a 

 nerve is followed along 

 from its centre, it is found 

 that it separates into small- 

 er bundles of fibres, which 

 run off as branches. These 

 branches again divide, and 

 so on, until the last branches 

 are very small and very 

 numerous. 



8. Sensory and Motor 

 Nerve-Fibres. A telegraph- 

 wire is used to send mes- 

 sages both ways. The same 

 wire will carry a message 

 just as readily from New 

 York to Chicago as from 

 Chicago to New York. Our 

 nerve-fibres are not used 

 in this way. Some of them 

 are always employed to car- 

 ry messages to the centres, 

 others to carry messages 

 from the centres. The fibres 



8. Point out an important differ- 

 ence between the carrying of mes- 

 sages by telegraph-wires and by 

 nerve-fibres. What is meant by 

 sensory fibres ? By motor ? 



