30 BIOLOGICAL PHYSICS 



nervous system, or structures, and finally exudes or is 

 exuded from the special exits, or from the free surfaces 

 of the skin and membranes, mucous and serous, and into 

 the sarco-lemmar sheaths of the muscle fibres to which 

 it is conveyed, and thence into the systemic lymphatic 

 circulation. A large quantity, therefore, but difficult of 

 measurement, must be constantly escaping through the 

 sensory and motor nerve terminals respectively, the 

 abnormal increase or diminution of which may initiate 

 pathological conditions of the greatest importance, the 

 removal and disposal of which must be sought for to a 

 large extent in a clear knowledge of the problems under 

 discussion. 



The nervous system in its entirety is inter-penetrated 

 by and bathed in this fluid initiated by and resulting from 

 the setting free of aqueous and organisable materials from 

 the blood in the process of developmental integration and 

 growth, or evolution of the embryo and foetus from the 

 substance of the impregnated ovum, the accumulation, or 

 increase, of which keeps pace with the increase in size of 

 these organisms, but fluctuates increasing and diminish- 

 ing within certain limits according to the necessities 

 arising from its altering and evolutionary conditions and 

 surroundings. The presence of this fluid, which in post- 

 natal life is recognised as the cerebro-spinal fluid or lymph, 

 throughout the spaces and inter-spaces of the nervine 

 structures is a vital necessity in the economy of the struc- 

 tures for supporting and protective purposes, as well as 

 a chemico-physiological agent in maintaining the vital- 

 ity and hygiene of the neuroglial amorphous elements. 

 Moreover, we would once more emphasise that its presence 

 thus throughout the universal systemic nerve elements is 

 necessary as an indispensable accessory in all functional 

 activity of the nervous system, whether central or peri- 

 pheral. In other words, nerve impulse can only be 

 permitted to travel within or through it in the normal and 

 physiological condition, and nerve stimuli can only reach 

 the stimulatable molecular nerve elements and textures 

 through it, and, therefore, that it performs something like 

 the function or work of the fluid in the economy of 

 the "wet cell" electric battery. Hence are explained the 



