EXTRACT XXXI. A. 



ON NEUROGENESIS, OR NEURONOGENESIS. 



NEURONOGENESIS signifies the origin, and development, of 

 the Neuronal or Neural unit, the totality of which consti- 

 tutes the systemic nervous system. 



The neuron is generated from the basal neuronic sub- 

 stance known as the Neuroglia, and owes its origin, there- 

 fore, to the preparation, and deposition, of that substance 

 within the blastodermic area known as the ectoderm. This 

 basal substance in brain, cord, and ganglia, after primary 

 deposition from the differentiating ovum, originates, and 

 develops, the spongioblasts, which in turn evolve the indi- 

 vidual nerve cells, and neural processes, dendritic, and 

 axonal, which ultimately inter-penetrate, and innervate, the 

 meso- and hypo-blastic related areas, and constitute, with 

 the sympathetic nervous system, the dual nervature which 

 controls, and determines, the vegetative, and higher organic, 

 life, of the completed organism. The neuron, besides 

 originating in, and growing from, the neuroglia, continues 

 to draw from that substance its materio-dynamic supplies, 

 through which it secondarily unites itself with, and sup- 

 ports, the structures known as, the skin, and the muscles, by 

 circulatory transference of matter and energy along the 

 axonal processes of the sensory, and motor, neurons, 

 respectively these axonal processes being hollow tubes, 

 or vessels, and not impervious filaments. 



The nutrition of the systemic nervous system is, there- 

 fore, due to the continuance of these neurogenetic 

 conditions on the evolution of the haemal circulation, 

 when the nutritive plasma is deposited from that circula- 



