THE SYSTEMIC NERVE CELL 315 



more, or less, circuitous intra-fibral journey, and performed 

 a prolonged functional work, of the very highest im- 

 portance, and of the widest textural range, or until they 

 reach the limits of the peripheral nerve terminations, 

 wherever situated, sensory, and motor, systemic, and 

 sympathetic, alike, where, their functional being com- 

 pleted, they are finally liberated, by the exfoliating 

 epidermic, epithelial, and endothelial, cells, and scales, 

 and the shedding skin appendages, as well as by the 

 musculature in which the motor fibres terminate ; besides, 

 to some extent, we would infer, in a, more or less, 

 amorphous form, by the sweat glands, and sebaceous 

 follicles, of the skin, and the various excretory agencies 

 developed within the texture of the various mucous, 

 and serous, membranes, of the body. It thus becomes 

 apparent, that secretions, elaborated by the nerve cells, 

 their nuclei, and nucleoli, from the surrounding neuroglial 

 pabulum, have to traverse the entire extent of the axonal 

 processes of the cells, i.e. the nerve fibres, from their 

 origin in the cells from which they respectively spring, to 

 their terminations in the various nerve terminal textures, 

 -or arborisations. This constitutes the inner division of, 

 what we may term, the great dual systemic nerve circula- 

 tion, or the combined, or duplex, nervine circulations 

 the other being the cerebro-spinal lymph circulation. 



The "growth" of the systemic nervous system may, 

 therefore, be said to begin as, or to consist of, a secretion 

 from the neuroglial matrix, to end as, an excretion, on the 

 various free surfaces, and enclosed spaces, in which the 

 nerve terminals end, and to consist of the stages of, 

 assimilation by the cells, their nuclei, and nucleoli, of 

 circulation, by, and through, the neurokeratinous tubes, 

 or vessels, known as the containing membranes, of the 

 medullary, or white substance of Schwann, and the axis- 

 cylinder, respectively, of incorporation with, or in, the 

 epidermic, epithelial, and endothelial, coverings, and 

 linings, respectively, as regards the sensory, and sympa- 

 thetic, distribution, and of the, more, or less, permanent 

 disposal, in the sarcous elements of the muscles, as regards 

 the motor distribution, of the nerve fibre terminals, and 

 of the final, exfoliation, shedding, or excretion, which ensues, 



