THE CHIEF CENTER OF THE NERVOUS SYSTEM. 595 



the digestive system as example, a group of neurons consti- 

 tuting the origin of a nerve would be able to automatically 

 continue its passive functions between meals. But just as the 

 onset of digestion, the active functional state of the stomach, 

 involves a reflex modification of the vibratory rhythm in all its 

 nervous supply, through the vagus, so would a nerve-center on 

 passing from the passive to the active state reflexly receive from 

 the posterior pituitary ~body the particular vibratory rhythm re- 

 quired by the organ to which its terminals are distributed. 



Professor Foster's reference to the central gray matter 

 as a bed "for the development of the nuclei of the cranial 

 nerves" suggests that the posterior pituitary might possibly 

 supply energy for all cranial nerves. The complex origins and 

 connections of the optic nerve would, under these conditions, 

 convert the posterior pituitary into a source of energy, pure 

 and simple, for general distribution. 



But the variety of cells which the posterior lobe contains, 

 as compared to the single type of ball-tipped fibers of the ante- 

 rior, suggests that such is not the case. Berkley says, referring 

 to the latter organ: "No nerve-ce/Zs are to be found in the sub- 

 stance of the organ, and all nerves belonging to it appear to 

 be derived from branches of the carotid plexus." This indi- 

 cates that nervous energy supplied by this organ to the supra- 

 renal system, while produced through the action of oxygen 

 upon the phosphorus-containing epithelial protoplasm and 

 therefore similar in kind to that produced elsewhere in the 

 organism, is due to a stimulating influence other than that 

 which prevails in the posterior lobe. In other words, while 

 the iodine in organic combination in the thyroid secretion is 

 the normal stimulus of the whole anterior lobe, and one of 

 the many stimuli to which it responds, the posterior lobe is 

 made up of many types of neurons which depend upon the leci- 

 thin formed between their protoplasmic partitions for their 

 functional activity. 



The organs differ markedly and significantly in one re- 

 spect, therefore: i.e., in the fact that, while the whole of the 

 anterior lobe is devoted to the one purpose of energizing the 

 suprarenal nerves, the posterior is an aggregate of many cen- 

 ters. This indicates, it seems to us, that, if the organ were a 



