560 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



cerebral nerve-fibers, we are brought to realize that the entire 

 nervous system is built upon the same plan: i.e., of fibrils con- 

 taining Hood-plasma, surrounded by a layer of my din. The main 

 constituents of these bodies, the oxygen of the plasma and the phos- 

 phorus of the myelin, are thus brought into contact, and nervous 

 energy is liberated. 



All this seems to us confirmed by the manner in which 

 many, now paradoxical, phenomena are accounted for: 



The production of nervous energy, not only by the neuron, 

 but also by the neural myelin, confirms the "avalanche" theory 

 of Pfluger, which, though at first combated by Marey, was 

 sustained by the latter after a series of experiments. Pfluger 

 held that nervous excitation increased along the length of 

 motor nerves: a view which strongly sustains our own. Duval 

 emphasizes this fact, and states that, while the stream of im- 

 pulses which he terms "molecular vibrations," in perfect 

 accord with modern physics travels 28 to 30 meters per second, 

 it "presents the characteristic of increasing gradually as it is 

 transmitted, i.e., as it advances in its nervous conductor." 

 Richet has found that excitation of a sensory nerve was more 

 intense when transmitted from the periphery than when ex- 

 citation was applied to a part of the nerve nearer to its center 

 (Duval). It is evident, therefore, that an accumulation of 

 energy takes place in sensory as well as in motor nerves. 



Our views are also sustained by the evidence afforded by 

 nerve-degeneration. Quoting Turck's conception, Professor 

 Barker refers to the Wallerian doctrine as follows: "Convert- 

 ing the Wallerian doctrine into terms of the neuron concept, 

 the following law may be laid down: When it has suffered 

 a solution of continuity, severing its connection with the cell- 

 body and dendrites of the neuron to which it belongs, the axon, 

 together with the myelin sheath covering it, undergoes in the 

 part distal to the lesion acute and complete degeneration. This 

 degeneration includes, not only the main axon, but also its 

 terminals, together with the collaterals and their terminals 

 connected with it." If the gradual increase of energy along the 

 nerve, just referred to, is considered as a factor of the function 

 and the sum-total of the energy utilized and is interpreted as 

 made up of neuron energy plus gradually increased nerve-energy, 



