366 BIOLOGICAL PHYSICS 



body, the systemic nerve cells are produced, once for all, 

 in numbers, exactly in accordance with the permanent 

 functional necessities of that system, and do not after- 

 wards increase in number, nor can be renewed if destroyed. 

 It may be said, in criticism of these statements, that the, 

 hard and fast lines of neuro-systemic structural evolu- 

 tion do not allow of the great functional advancement 

 achieved in the persons of individuals, of " light and 

 leading," who have been, more or less, in evidence, in 

 every age of the world's history, and whose systemic 

 nerve structures must have been superiorly developed, 

 in spite of the limitations of neuro-cellular, addition, and 

 renewal ; but in answer to this criticism, we would venture 

 the opinion, that the difficulty involved may be quite 

 satisfactorily met, by the ability, and power, of every 

 systemic nerve cell, to develop new processes, amcebally, or 

 by the strengthening, and lengthening, of those primarily 

 developed ; moreover, the effect of continuous, and syste- 

 matic, exercise, within the bounds of physiological safety, 

 is always productive of expansion of structure, and increase 

 of functional energy so we would account for the seem- 

 ing contradictoriness of the above conditions, and state- 

 ment, of facts, by adducing these physiological axioms, as 

 quite sufficient to meet the difficulties. 



The systemic nerve cells, and processes, are, necessarily, 

 the structural products, and functional formative work, 

 of the sympathetic nervature, and are dependent for their 

 combined existence, on the nutritive materials provided 

 by the activity of that nervature, from where its related 

 haemal vasculature, deposits the required pabulum, amid 

 the delicate neuroglial fibre-cellular textures of brain, 

 cord, and ganglia. 



A systemic nerve cell, if once lost, is lost for ever, 

 while a sympathetic nerve cell, if lost, can be renewed, or 

 rather substituted, by prolification from a neighbouring 

 cell, so that the continuity of the bodily, so-called, non- 

 nervous textures can be perpetually secured, and the 

 integrity of the body, though paralysed, sustained, and 

 made habitable to, it may be, an unclouded, and active, 

 mind. In such a condition as that here described, 

 moreover, we see plainly, also, the dual nature, and 



