530 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



suffice to insure nutrition and to hold the structures thus sup- 

 plied ready for active work. What is the source of this energy? 



If the posterior pituitary reinforces the flux of impulses 

 when functional activity is demanded, passive energy would 

 seem to require another source, and as the lower, or middle, 

 brain and the cord are included in the "sphere of influence" 

 of this organ, the hemispheres are the only parts of the en- 

 cephalon that can supply the need. But they do not. Removal 

 of the hemispheres, we have seen, does not impair muscular 

 activity; a frog can jump, a pigeon can fly, etc., and, after a 

 short period of shock-paralysis immediately after the opera- 

 tions, movements return: evidence that their nutritional 

 metabolism, incited and regulated by nervous impulses, con- 

 tinues. Evidently, therefore, the hemispheres have nothing 

 to do with the process; they are solely the seat of the "mind," 

 and constitute an organ among the rest, itself supplied with 

 vasomotor nerves (Obersteiner, Gulland, Huber, Hiirthle, 

 Cavazzani, Frangois-Franck, et al), and probably with its own 

 nutritional nerve-system. We are, therefore, brought back to 

 the posterior pituitary as the only organ capable of satisfying 

 the needs of the situation: i.e., as the only source of passive 

 energy. 



This suggests that metabolism may suffice, through the 

 agency of the blood's oxidizing substance, to sustain physio- 

 logical activity during the intervals between "stormy processes 

 of the nerve-fiber"; but this is promptly shown to be a wrong 

 interpretation when the effects of section below the medulla 

 are recalled. As all the arteries of the organism are imme- 

 diately relaxed, a continuous stream of impulses must have 

 served to hold the vessels in tonic contraction: evidence that 

 passive nervous energy is a factor to be reckoned with. Thus, 

 the fact that all co-ordinated muscular movements continue 

 after removal of the hemispheres relegates to the middle brain 

 the function of supplying active energy and, obviously, 

 passive energy likewise, the need of the latter being shown by 

 division of the medulla. Indeed, passive energy may well be 

 described as passing to and fro in a given nerve-fiber in the 

 intervals between the more violent excitations, while active 

 energy can as fittingly be likened to "a stormy process in the 



