THE CIRCULATION OF CEREBRO-SPINAL. SUBSTANCE. 581 



supply of nervous energy, all the systemic axonal and dendritic 

 end-organs are in a state of constant vibration. 



In our analysis of muscular contractility we made the fol- 

 lowing statements: "The impulse-wave simply sets the muscle- 

 elements to a given vibratory rhythm, and they retain this 

 whatever be the intensity of the exertion required. . . . 

 This may aptly be compared to the manner in which a note 

 on a violin is made loud or soft. The power with which the 

 string is pressed upon with the moving bow modifies the in- 

 tensity of the sound; but the note remains the same. This 

 means that its pitch does not vary, and if, for example, the 

 lower C is given, we will know that the sound-wave of that 

 note represents two hundred and sixty-one vibrations per sec- 

 ond. So may the impulse-wave transmitted by the brain 

 through a 'motor' nerve be represented by a fixed number of 

 vibrations. Eetraction, the muscle being then most tense, is 

 therefore characterized by the greatest number of vibrations/' 

 If this interpretation is sound, it is likewise applicable to the 

 "to-and-fro" motions of the bulbous terminals which constitute 

 vibration, the number of these motions within a given time 

 representing a given intensity. Any modification of the num- 

 ber of these to-and-fro motions within a given time, therefore, 

 correspondingly modifies the intensity of the resulting vibra- 

 tory impulse-wave, the PASSIVE state of function (that during 

 which cell-nutrition alone occurs) l)eing represented ~by the lowest 

 number of vibrations, the ACTIVE stage (during which the function 

 is in full sway) by the highest number of vibrations compatible 

 with normal health. 



Still, in accordance with our views, this applies to the im- 

 pulses transmitted by the posterior pituitary body, since this 

 organ, directly and through its extension in the cord, governs 

 the passive stage of function and incites the cellular elements, 

 both through the terminal vasomotors and the net-works dis- 

 tributed to the cells themselves, to higher activity when the 

 active stage becomes necessary. Can we say the same of the 

 independent hemispheres? This carries us back to the circu- 

 lation of the brain, for the question involves another: i.e., 

 whether the cerebro-spinal functions, active and passive, are 

 carried out in a manner similar to that of all other organs. 



