168 THE HUMAN BODY. 



posture quietly, the tonus is present and suffices to keep the Body 

 in position, but let any active movement be started, either voli- 

 tionally or reflexly, and the opposition to that movement which 

 would be offered by a persistence of the tonus is removed by its 

 complete cessation. This fact has been proven conclusively. For 

 details the reader is referred to larger works on the nervous system. 



