722 COMPARATIVE. HISTORICAL. 



first reference to reflex movements was made by Des Cartes (1670) . Stephen Hales 

 and Robert Whytt showed that the spinal cord was necessary for their occurrence. 

 Prochaska first demonstrated the reflex path. Duverney (1761) discovered the 

 ciliary ganglion; Varolius (1573) the chorda tympani. Gall traced more accu- 

 rately the third and the sixth nerves, as well as the spinal nerves, into the gray 

 matter. Up to this time only nine cerebral nerves were described. Sommering 

 (1791) differentiated the facial and the auditory; Andersch (1797) the ninth, 

 tenth and eleventh nerves. 



