522 BIOLOGICAL PHYSICS 



or blending with, the air spaces of the base of the skull 

 and upper bones of the face. 



In this latter anatomical arrangement, we think, is 

 provided a means of external drainage of the intra-cranial 

 lymph spaces through the patent mechanism afforded by 

 the Pacchionian bodies on their traversing the inner table 

 of the skull and cancellous texture of the overlying diploe, 

 and it may be to some extent the outer table and peri- 

 cranium, hence the growth of " wens," etc. 



Thus, this osseous encasement affords both protection 

 and support of the most substantial character to the 

 central nervous system, while at the same time it provides 

 facilities for a supplementary lymph drainage system by 

 which the exigencies of intra-cranial pressure can be met, 

 and, it may be, neutralised, on the principle of " give and 

 take," or " tidal fluctuation," so to speak. 



