THE ANIMAL A MACHINE 



187 



are subject to our will, but also upon all the internal organs. 

 These organs are provided with a special set of nerve fibers 



Fig. 74. Diagrammatic View of a Nerve Fiber and a Muscle Cell and 



Their Interrelation 



The picture shows the highly involved niake-up of nerve and muscle 

 cells, billions of which are in our body. In the upper part of the picture 

 the nerve-cell with its numberless nerve-fibers is seen. One of the fibers 

 is particularly magnified and its details pictured. Below, the termination 

 of the nerve on a highly magnified muscle fiber is pictured. It is seen also 

 that the muscle fiber in turn consists of an immense number of smaller 

 fibers each of which shows peculiar cross striation. At the left are highly 

 magnified pictures of one such small muscle fibril. At the right is a highly 

 magnified aspect of a single nerve fiber. 



which do not directly connect the internal organs with the 

 brain, but pass first through a number of intermediate 



