60 BIOLOGICAL PHYSICS 



pia mater proper generally, more in the manner of the 

 pleurae, pericardium, and peritoneum. 



The formation of the cerebro-spinal lymph being thus 

 effected, and its renewal and regular supply being thus 

 secured, by the functional activity of the pia mater proper 

 and its attached choroid plexuses, let us pursue the study 

 of it, in its course of circulatory disposal, in its important 

 functional work within, and without, the nervous system, 

 and in its final elimination as an excretionary fluid, and 

 bearer, of effete nervine matter and neuroglial debris. 



Before doing so, and departing from the subject of the 

 pia mater as a secretory medium, we should remark that 

 its secretory role lies at the foundation of the genesis, 

 growth, and entire organic integrity of the brain and 

 nervous system. Thus, from its blood-vessels it distils 

 the cerebro-spinal lymph from the liquor sanguinis of their 

 contained blood into the lymph areas, and inter-spaces, 

 of the entire nerve organism, while at the same time it 

 deposits, in the matrix of the neuroglia, the nutritive 

 pabulum for the support of that organism with its 

 imbedded, and outgrowing, neurons, thus unburdening 

 itself simultaneously of a double set of materials destined 

 to perform very different functional roles in the economy 

 of cerebration and innervation, and nervine work generally. 



