372 BIOLOGICAL PHYSICS 



which they are developed, and whose innervation they 

 simultaneously effect. Thus, the substance of the outer 

 layers of the skin, with their local modifications, and 

 appendages, the epithelial, and endothelial, surfaces of 

 various membranes, the parenchyma of certain viscera, 

 and the sarcous elements of the muscular structures, 

 all benefit nutritionally, by the " cast-off," or excreted, 

 plasma, of the systemic nervous system. 



In its beginnings, and its endings, therefore, the 

 systemic nervous system is structurally continuous with, 

 its non-nervous, or sympathetically innervated surround- 

 ings, in virtue of which it is directly nourished by them, 

 and in turn vitalises, and energises, them, at its distal 

 termination. In passage through, or conveyance along, 

 or amid, these structures, it, however, is completely 

 separated, and insulated, from its surroundings, by the 

 non-conducting, and insulating, textures, surrounding, 

 and enclosing, its component cells, and fibres. These 

 remarks apply to the systemic nervous system, although 

 they apply, to some extent, also, to the sympathetic 

 system, in its relationships, ganglionic, and neuro-fibral, 

 to what, may be called, the quasi-nervous textures, which 

 it innervates, and the maintenance of whose life is entirely 

 due to it, as well as the non-nervous elements of the 

 systemic nervous system, to which latter it is distributed 

 as the nervi nervorum, which circumstance indicates, that 

 the maintenance of the vitality of structure is essentially 

 due, to the action of the sympathetic nerve energy, and 

 plasma, and that this materio-dynamic combination suffices 

 to maintain the life of structure, from its origin in the 

 fecundated ovum, long antecedent to the development of 

 the systemic nervous system, until its somatic death, 

 which may be preceded by the virtual death, or functional 

 disability, of the systemic nervous system. 



We may regard it, we think, therefore, as axiomatic, that 

 all merely vegetative, or animal, life, apart from the higher 

 functional life maintained by organic forms, is due to, and 

 maintained by, the action of sympathetic nerve energy on 

 the elements of organic protoplasm, in the processes of 

 living analysis and synthesis, which constitute the vital 

 role of living matter. 



