SENSORY, MOTOR & PSYCHIC NEURONS 407 



layers of grey substance, without being broken up, are 

 received, rearranged, and passed on by the second, to the 

 next interpolated cells, to be finally distributed, in terminal 

 arborisations, peripherally, or in continued successional 

 cell progress, until at last they pass into, and become 

 structurally incorporated with, the cutaneous and skeletal 

 textures, to which the systemic nervature is finally dis- 

 tributed. Be that as it may, the manner of union 

 between successive neurons, through axis-cylinder sub- 

 stance agency, allows of independent activity of each 

 nerve cell unit, and secures its contribution of individual 

 functional work to the sum of communal neuronal work, 

 and the credit of the entire cerebro-spinal neuro-dynamic 

 industry. 



The relationships between the absolutely mental neu- 

 rons, the cerebro-spinal, sensory, and motor neurons, and 

 the co-related sympathetic nervature, are of the most 

 profoundly intricate and, so to speak, remote character, 

 as well as of the most delicate nature structurally, so that 

 the most powerful microscopes fail to penetrate their 

 inner mode of working, and the most finished modes of 

 experimentation fail to elicit more than the faintest flashes 

 of intelligible meaning and information ; here, therefore, 

 a great deal must needs be taken for granted, and a 

 scientific faith must needs be exercised, which will place 

 the votaries of science on a platform almost identical 

 with that held by the exponents of revelation and 

 theology. 



As bearing on the understanding of the working of 

 the neuro-dynamic machinery of the highest, or mental, 

 nerve centres, we would quote, as a quite relevant 

 speculation, founded on a species of textural elimination 

 of the various cerebral contents, a study of this series 

 called : " In search for the home of the ego," in which 

 it is claimed that the totality of the nucleoli of what we 

 would now call the mental, or psychic, nerve cells constitutes 

 that " home," or the particular, or peculiar, habitat of 

 the mind. 



The mental nerve cells, or mind occupied neurons^ of the 

 cortical and central grey substance of the cerebrum, end 

 in the central, or upper, cerebro-spinal, sensory, and 



