506 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



spective perception-centers would enter within the scope of 

 this central brain. 



As to the source of the transmitted energy or impulses, 

 apart from the sensory connections with underlying structures 

 which the cortex possesses, the predilection of most writers 

 to ascrihe to the cortical areas motor functions but demon- 

 strates the need of such an agency to logically account for the 

 phenomena witnessed. To ascribe to the central brain or its 

 centers per se attributes of a similar kind would simply amount 

 to shifting to it a convenient, but unknown, quantity, and a 

 fictitious one besides, in the sense that it supplies nothing to 

 account for something. In the only nervous system that we 

 have so far traced to its origin, that of the suprarenal glands, 

 the conversion of chemical energy into nervous impulses was 

 found to be a functional attribute of the anterior pituitary 

 body. That so extensive a system as that represented by the 

 central brain and cord should likewise need a center such as 

 that represented by the posterior pituitary body for the con- 

 version of some form of energy of external source to satisfy 

 the needs not only of its efferent, but also its afferent, im- 

 pulses seems clear. 



That the middle brain is the source of the motor phe- 

 nomena witnessed is not only suggested by the fact that nor- 

 mal muscular contractility promptly recurs after removal of 

 the hemispheres, but also by the following experiment by 

 Professor M. Duval: "If a part of the gray substance of the 

 cortex designated as the center of certain movements is cau- 

 terized, the same movements are obtained when the electrodes 

 are applied upon the eschar thus produced. . . . This 

 experiment shows," says the author, "that the gray cortical 

 substance is not a necessary experimental condition for the 

 production of localized movements." Indeed, he states that 

 the underlying white substance of certain parts will also cause 

 circumscribed motions in certain groups of muscles, etc. 



Can the removal of the cortex of one side be followed by 

 the assumption of compensative functions by the opposite side ? 

 After the usual period of paralysis, due to shock, the normal 

 motions promptly recurred, precisely as they had on the other 

 side. To ascertain whether the cortex at all possessed motor 



