504 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



lobe was destroyed and in which the only symptoms were 

 amaurosis and slight headache. This emphasizes the identity 

 of the cerebral hemispheres as an aggregate of centers which 

 record impressions and are the seat of reason, intelligence, and 

 volition, but it also suggests that the word "motor" is only 

 applicable in its literal sense to the areas in the lower cerebral 

 mechanism: i.e., the intermediary through which the mandates 

 from the hemispheres are executed. 



We have previously referred to the misleading information 

 afforded by the use of electrical stimulation. Nowhere in the 

 organism does this seem to be more applicable than to the 

 brain. This feature and the complexity of the processes in- 

 volved are fully emphasized in the following lines of Professor 

 Foster: "Some writers appear to entertain the conception that 

 in a voluntary movement, such as that of the forelimb, all 

 that takes place is that the 'will' stimulates certain cells in 

 the cortical area, causing the discharge of motor impulses along 

 the pyramidal fibers connected with those cells, and that these 

 motor impulses travel straight down the pyramidal tract to 

 the motor fibers of the appropriate nerves, undergoing pos- 

 sibly some change at the place in the cord where the pyramidal 

 fiber makes junction with the fiber of the anterior root, but 

 deriving their chief, if not their whole, co-ordination from the 

 cortex itself: that is to say, being co-ordinated at their 

 starting-point. That such a view is untenable and that the 

 simplicity of the electrical phenomena is misleading are shown 

 by the following two considerations, among others: On the 

 one hand, as was shown in a previous section, the co-ordination 

 of movements may be carried out apart from the cortex, 

 namely: in the absence of the hemispheres; and we can hardly 

 suppose that there should be two quite distinct systems of co- 

 ordination to carry out the same movement: one employed 

 when volition was the moving cause, and the other when some- 

 thing else led to the movement. On the other hand, the 

 analogy of speech justifies us in concluding that the cortical 

 processes do take advantage of co-ordination effected by the 

 action of other parts of the nervous system." 



Referring directly to the general character of the processes 

 involved, Professor Foster says: "Hence, while admitting, as 



