150 BIOLOGICAL PHYSICS 



one, but also, as we elsewhere contend, an excretionary one. 

 We want, therefore, to be consistent in our estimate of its 

 true place in the economy of neural physiology, to disclaim 

 for it the nutritive function which it has been sometimes 

 credited with serving, inasmuch as we contend that the 

 nutritive material which it is supposed to convey to the 

 nervous textures is, during its formation, deposited from the 

 blood, as g/ia, in the neuroglial feltage, where it is taken up 

 by the dendritic processes of the nerve cells, and con- 

 verted into nerve plasma within each cell, according to its 

 individual and systemic requirements. The yielding of an 

 elastic support and bufferage to the structures which it 

 encloses may, therefore, be described as its main mechanical 

 office, together with the maintenance of the proper propor- 

 tion of moisture in the inter-spaces of the brain, cord, and 

 nerves to secure the requisite plasticity of the true nervine 

 elements and the needful excretional circulation from 

 within these elements. Along with its excretional disposal 

 of effete nervine material, we would also include the 

 " excretional " disposal, or radiation, of surplus central 

 caloric and the maintenance of the normal body tempera- 

 ture, a function which the universality of its presence, 

 circulation throughout, and exits from the body render 

 possible and functionally easy of accomplishment. 



As illustrative of the truth of the last-mentioned func- 

 tional work of the cerebro-spinal fluid, we would only call 

 attention to its almost constant disturbance in all diseased 

 conditions in which rise and fall of body temperature take 

 place, the main reason for such rise and fall being the 

 disturbance of cerebro-spinal lymph circulation and excre- 

 tion and consequent interference with heat radiation. 



The cerebro-spinal fluid, as a culture medium, and 

 viewed in relationship to the infective invasion, incubation, 

 and distribution of bacterial organisms and disease germs, 

 may be regarded as the most ideally perfect to be found 

 within the whole body, on account of its intrinsic qualities, 

 histological environment, comparative isolation and means 

 of graduated escape available for shedding or emigration ; 

 it will, therefore, we think, be found, as research progresses, 

 that a very much larger number of pathogenic bacterial 

 organisms owe their existence and propagation to this fact 



