510 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



better convey the mutual relations of the various structures 

 included in this system than a verbal description. 



Again, the location of the posterior pituitary at the very 

 head of the entire spinal system, as shown in the illustration, 

 adds further testimony to that already submitted to demon- 

 strate the functional relationship between the nervous struct- 

 ures lying in the posterior pituitary, including the floor of the 

 fourth ventricle, and the bulb. 



To ascertain this was the main purpose of our inquiry 

 into the comparative functional attributes of the hemispheres 

 and the middle brain. But we must not lose sight of the 

 fact that, in doing this, we have also given nerve-impulses their 

 true identity as mechanical energy: i.e., energy similar to that 

 supplied to the suprarenal system by its center, the anterior 

 pituitary. That a center for the conversion of chemical energy 

 into mechanical energy should be necessary for a relatively 

 short nerve-path as is that of the suprarenal system indicates 

 the physiological need of such a center as a source of energy 

 for all nerves. 



A summary of all these facts, i.e., (1) that the posterior 

 pituitary body has a phylogenetic history which distinctly 

 identifies it as a part of the entire neural tract; (2) that it 

 presents clearly defined histological characteristics of an active 

 neural organ; (3) that these characteristics extend to the in- 

 fundibulum, the tuber cinereum, the floor and sides of the 

 third ventricle; (4) that these structures are continuous with 

 the reticular substance of the tegmental region, the medulla, 

 and the cord; (5) that the posterior pituitary body has been 

 found to be in direct relation with the olfactory center and 

 the bulbo-spinal axis in all classes of vertebrates; (6) that a 

 current passed between the olfactory and bulbar centers may 

 cause heart-inhibition and death; (7) that all the nerve-centers 

 are included in the structures with which the pituitary is func- 

 tionally connected in all vertebrates; and finally (8) that death 

 is caused by a puncture in the region of the vagal bulbar center 

 through interruption of the efferent and afferent impulses 

 through which the cardio-pulmonary system is incited to ac- 

 tivity and governed, seems to us to warrant the conclusion 

 that: 



