REFLEXES 



51 



nervous system from the larynx, with the result that 

 most of the conspicuous trunk muscles are made to share 

 in the convulsive response. It is easy to account for this 

 spread of the impulses in the light of the apparent ana- 

 tomic organization of the gray matter. 



The general rule seems to be that one afferent neuron 

 makes connections with a number of efferent elements. 

 A diagram (Fig. 8) will be helpful. It is possible by an 



Fig. 9. The adjusters extend the effect to a greater number of 



efferent paths. 



extension of this principle to visualize a mechanism 

 which will insure the most multifarious discharge of im- 

 pulses after a solitary afferent conductor has been ex- 

 cited. But the painstaking histologists who have done 

 most to interpret the finer structure of the gray matter 

 believe that the spread of the process is accomplished 

 largely through the interposition of neurons of a third 

 order between those which are clearly afferent and those 

 which are definitely efferent. These, according to our 



