THE CONQUEST OF DISEASE 



the hope of relieving intractable neuralgia, is 

 no longer made. 



The knowledge of the degeneration and re- 

 generation of nerves followed; and the func- 

 tions of the sympathetic nerves were discov- 

 ered. Cesalpinus (1571) found that interrup- 

 tion of the blood stream rendered parts insen- 

 sible; Galvini (1791) studied the reflexes by 

 applying electric stimuli to frogs' legs; 

 Stephen Hales and Robert Whytt showed that 

 the spinal cord is necessary for reflex move- 

 ments; and Marshall Hall worked out the 

 whole problem of reflexes. The discovery of 

 the nervous mechanism controlling the heart 

 and circulation, and the demonstration of the 

 nervous influences controlling secretion depend 

 upon animal experiments. 



Out of these studies has grown the necessity 

 for instruments of precision; and we have to 

 thank physiology for many of the methods of 

 making examinations of the sick which enable 

 us to differentiate them from the well. The 

 greatest precision is demanded by the physiolo- 

 gist in his studies ; and the diagnostician is able 

 to apply the same methods to man. 



