

744- 



THE POPULAR SCIENCE MONTHLY. 



ing the functions of the pons Varolii. Section or irritation of this 

 organ is followed by powerful movements, and much more pronounced 

 signs of pain than any previously manifested. If we cut the anterior 

 portion of one side of the pons, movements will be produced on the 

 opposite side of the body, and the vertebral column will bend toward 

 the side of section. It has been shown that the deeper posterior parts 

 of the pons are made up of transverse fibers connecting the two lobes 

 of the cerebellum, and we find, as we should expect, that injury to one 

 side of this portion of the organ causes the same rolling movements as 

 appear upon one-sided injury to the cerebellum. 



If we remove all the encephalic centers above the pons, the animal 

 so treated will maintain his upright position, will give cries quite char- 

 acteristic of pain, and will bring about conjoined movements of flight. 

 These manifestations disappear completely after removal of the pons, 

 and we have left only those reflex activities already shown to be de- 



FiG. 11.— Longitudinal Section thuotjgh the Center op the Brain, ehowins: the inner face 

 of Left Cerebral Hemisphere. (Sappey, after Hirschfeld.) 1. spinal cord ; 2, pons Varolii ; 

 3, Cerebral peduncle; 4, " arbor vitae " of cut surface of middle lobe of cerebellum ; 5, Sylvian 

 aqueduct; 6. valve of Vieussens; 7, corpora quadrigemina ; 8, pineal body; 9, its inferior 

 peduncle; 10, its superior peduncle; 11, middle portion of the great cerebral cleft ; 12, upper 

 face of the thalamus ; 13, its internal face, forming one of the walls of the middle or third 

 ventricle. 



pendent upon the cord and medulla. It seems clear that in the cell- 

 masses of the pons the movements essential for locomotion, for main- 

 tenance of upright position, and for expression of pain, are combined. 

 These phenomena have led many physiologists, among them Longet, 

 to consider the pons as a sensorium commune, or the place where the 

 sensations are assembled, and where the movements caused by sensa- 

 tions arise. Other physiologists, among them J. Mtiller, believe that 

 the pons is the seat of the power of volition. I would reserve my 

 opinion as to the relation between this organ and consciousness until 

 after the functions of other nerve-masses between the pons and cere- 

 bral hemispheres have been considered. 



