REFLEX CENTERS OF THE MEDULLA 



541 



among those in this group. When certain of these centers are interfered 

 with, death follows. 



Life may continue when the spinal cord is cut away in successive portions 

 from below upward as high as the point of origin of the phrenic nerves. In 

 amphibia, the brain has been all removed from above, and the cord removed as 

 far as the medulla oblongata from below; yet so long as the medulla oblon- 



FIG. 380. Diagram of Ascending Conduction Paths from the Cord through the Medulla and 

 the Thalamus to the Cerebral Cortex. (Cunningham.) 



gata was left intact, respiration and life were maintained. But if the medulla 

 oblongata is wounded, particularly if it is wounded in its central part oppo- 

 site the origin of the vagi, the respiratory movements cease, and the animal 

 dies from asphyxiation. This effect ensues even when all parts of the nervous 

 system except the medulla oblongata are left intact. 



Injury and disease in men are accompanied by the same nerve disturbances 

 as are exhibited by these experiments on animals. Numerous instances are 

 recorded in which injury to the medulla oblongata has produced instantaneous 



