THE CENTRAL SENSORIUM. 599 



successively removed, the animal still shows, by characteristic 

 agitations and plaintive cries, the pain it experiences when sub- 

 mitted to strong external excitations: i.e., when its leg is 

 squeezed with pincers or a bare nerve is excited. If the pons 

 itself and the upper part of the medulla are now destroyed, the 

 animal at once ceases to respond by similar cries and agita- 

 tions/' . . . "An animal that has lost its pons has there- 

 fore lost a center for the perception of sensitive impressions." 

 The gray ganglionic substance of the pons is, we have seen, a 

 part of the central gray matter which begins in the posterior 

 pituitary body: a fact which suggests that the latter is the 

 seat of functions now ascribed to this part of the pons. 



Indeed, these instinctive involuntary acts are dominant in 

 the entire phylogenetic scale even in vertebrates devoid of skull 

 or brain: the amphioxus, for example, down to which Andriezen 

 traced the structures which ultimately become the pituitary 

 bodies. It is difficult to conceive of an inciting and governing 

 efferent impulse from the posterior pituitary without an af- 

 ferent impulse conveying to it the needs of the organ to be 

 incited to activity and governed. Duval refers to weeping, for 

 instance; tears, we have seen, are brought on by increased cir- 

 culation and stimulation of the cellular elements of the lacry- 

 mal glands; what is this but functional activity enhanced by 

 impulses to the posterior pituitary if our previous conclusions 

 are at all warranted? 



True, we are dealing primarily with a mental phenomenon, 

 but this only proves that afferent impulses may reach the poste- 

 rior pituitary from the cortex of the hemispheres as they can 

 from any organ. Nor is the act an instinctive one; but this 

 fact also affords supporting testimony, since it demonstrates 

 that the organ is not only influenced by impressions of a purely 

 reflex kind, or connected merely with organic life, but also by 

 the highest form of nervous action: i.e., mentality. What 

 better evidence can we have of this than the violent cardiac 

 action; the trembling; the involuntary excretion of urine, of 

 fasces, of sweat; or even the sudden arrest of the heart, all of 

 which phenomena may attend intense fear, and all due to loss 

 of control ~by the posterior pituitary, under the violence of the 

 mental impulses over . . . muscular tissue: cardiac, skele- 



