ON CIRCULATION GENERALLY 41 



us that the pabulum required for the support of the 

 various textures composing that organ is laid down from 

 the pial capillaries within the neuroglia, and comprises 

 a large portion of the amorphous material, or stroma, of 

 the neuroglia ; that the organic matrix of the neuroglia 

 and the neuronal cells and fibres are sympathetic in origin, 

 the former being mainly protecting and supporting and 

 neuronogenetic ; that they together afford the soil and 

 seed from which the systemic nerve elements proper, or 

 neurons, originate, grow, and prolong their axonal pro- 

 cesses, and that the nerve cells proper grow by imbibition 

 through their dendritic processes with attached gemmules- 

 (like a plant by its rootlets from the soil) from the sur- 

 rounding neuroglial amorphous materials. What takes 

 place in this process resembles, and may, in a sense, be 

 described as a sort of secondary digestion, the gemmules- 

 of the dendritic processes selecting and preparing the 

 required nutritive materials for their respective nerve cells,, 

 the latter doing the same for their nuclei, and these in 

 turn for their nucleoli. 



The individual cell, with its processes, dendritic and 

 axonal, its contained nucleus and nucleolus, may, as thus 

 described, be taken as representative of a typical neuron 

 or a nerve unit, the multiplication and totality of which 

 constitute the systemic nervous system. Here, therefore, 

 comes in the necessity for the provision of an efferent 

 system of lymph circulation which will carry the results 

 of nerve waste and disintegration safely out of that 

 system, and out of the system generally, and will so 

 prevent the toxic effects likely to follow from the retention 

 of the "doubly distilled" results of haemoneural "wear 

 and tear." The system of cerebro-spinal lymph circula- 

 tion may, therefore, literally be said to run off "brain 

 sweat" from and through the peri-vascular and connected 

 peri-neural spaces into the cerebro-spinal intra- and inter- 

 spaces, or the ventricular spaces, the central canal of the 

 cord, and elaborated sub-arachnoid and sub-dural spaces, 

 with the related and continued peri-neural inter-spaces 

 which, in continuity, accompany the various cephalic and 

 spinal nerves in their entirety to their outer extremities^ 

 cutaneous and muscular. 



