THE CEREBRO-SPINAL FLUID 115 



spinal cavity respectively, may be looked upon as the main 

 drains and residual excretory channels from the two great 

 structures, the brain and spinal cord. 



The third, or cutaneous, may be regarded as affording 

 a great peripheral drainage system to the whole of the 

 sensory nerves, as a safety valve for the escape of super- 

 abundant cerebro-spinal fluid when the two first are 

 impeded from any cause and unavailable, hence the impor- 

 tance of recognising their relationship with each other, or 

 interdependence, as one of reciprocity. 



The fourth, the muscular, with the attached general 

 lymphatic system, acts as a drainage system to the motor 

 side of the cephalic, cervical, thoracic, lumbar, and sacro- 

 coccygeal nerves, as to their anterior roots, and hence 

 drains into the substance of the various muscular struc- 

 tures to which they are distributed, i.e. to the whole 

 voluntary muscles of the body. The union of the nervous 

 and muscular systems being one of the greatest intimacy, 

 in fact, of continuity, the drainage from the whole motor 

 area of the systemic nervous system is ejected, or rather 

 injected, into the sarcolemmar and sarcous elements of the 

 muscular textures, to be taken up by the systemic lymph 

 circulation, or driven by continuity from texture to texture 

 until they become finally eliminated from the system, or 

 become pathological entities, or " materies morbi " amid 

 the structures in which they may be finally retained. 



It will thus, we think, be seen that the maintenance of 

 the patency and integrity of these various drainage systems 

 becomes a physiological work of the greatest importance in 

 its application to the individual, and a hygienic task, to 

 help which is not to be despised by the practices of the 

 healing art, the fourth, or muscular, calling for even special 

 attention. A subsidiary system of this drainage, we think, 

 may also be found into and along the sympathetic nervous 

 system (Fig. 42) through its abundant filamentous con- 

 nections with the systemic nervous system. 



The consideration of the subject of excretion from the 

 cerebro-spinal lymph cavities may be carried a step farther 

 by regarding the orbits with their contained accessory parts 

 as conducive to that function. Thus the eyes are said to 

 " stare," or to stand out of, to " sink," or to be drawn into, 



