26 BIOLOGICAL PHYSICS 



engender disease, most especially of the muscles and all 

 the structures in which they end, and with which they are 

 functionally connected. 



To distinguish between the lymph proper and the fluid 

 contents of the cerebro-spinal cavity and related nerve 

 channels, it might tend to a clearer and more exact appre- 

 hension of the physiological situation involved in the 

 foregoing remarks, were we to adopt permanently the 

 terms haemal and neural, the former term applying to 

 the lymph within the lymphatics proper, and the latter 

 to the cerebro-spinal fluid. 



Naturally, these two fluids differ somewhat in chemical 

 composition and physiological character, in consequence of 

 their difference in genesis, and the very different offices 

 they subserve in the economy of nutrition and elimination 

 the haemal lymph being mainly, if not entirely, engaged 

 in the work of sanguification, nutrition, and the removal 

 of disintegrated material from the extra- or non-systemic 

 nervine structures, while the neural lymph has its func- 

 tional role confined within the precincts of the cerebro- 

 spinal nerve structures proper, with the exception of their 

 neuro-muscular aspect. 



The former, or haemal lymph, is rich in nutritive and 

 corpuscular, or organic, materials because of its nutritional 

 position, while the latter, or neural, is destitute of such 

 elements, being mostly concerned in chemico-mechanical 

 work, or, at any rate, work of that character, together with 

 the most important function of removing from within 

 the inter-spaces of the systemic nervous system the disin- 

 tegrated and effete materials resulting from the functional 

 activity of that system, or, as we may express it, the 

 " doubly distilled" residuum of the vital " tear-and-wear " 

 of both the haemal and the neural systems, so to speak. 



These things being so, we would expect to find, and 

 are warranted in anticipating, that the neural lymph, in 

 virtue of the dual concentration of its effete constituents, 

 should be circumscribed, in the extent of its intra-systemic 

 circulation, as far as is possible, and should be walled off 

 from the haemal streams of lymph, and conveyed out of, 

 or from within, the precincts of the systemic nervous system 

 directly, and without allowing a possibility of the occur- 



