n6 BIOLOGICAL PHYSICS 



their sockets, the reason of which must be sought for in 

 the distribution of the more liquid and plastic contents of 

 the orbits. These contents are continuous with the con- 

 tents of the cerebro-spinal cavity, and hence must be 

 affected more or less by the influences affecting that cavity 

 in relation to intra-cranial and intra-spinal pressure. 



For example, a paroxysm of whooping cough may result 

 in profuse lachrymation, injection of the conjunctival 

 vessels, with other intra-ocular changes, to which may be 

 added more or less swelling of the whole palpebral 

 regions. 



Again, an attack of choleraic diarrhoea is usually quickly 

 followed or accompanied by a " sinking " of the eyes, which 

 in this light we may regard as a withdrawal of the fluid 

 usually present within the orbits, through the foramina 

 communicating with the cranial cavity, as a consequence of 

 the strength of the currents, serous or lymph, towards the 

 excreting intestinal mucous surfaces. 



These may be regarded as typical examples of the role 

 played in the economy of excretion from the nervous 

 system by the " ebbs and flows " of the cerebro-spinal fluid, 

 in its functions of floating that system and providing a 

 means of disposal for its effete materials. 



The horizontal position in some individuals, a prolonged 

 act of stooping, or the suspension of the body head down- 

 wards, will induce swelling or puffing of the eyelids by, on 

 this theory, allowing the fluid cerebro-spinal contents to 

 gravitate into the orbital cavities through the before- 

 mentioned foramina, the sub-dural and sub-arachnoid spaces 

 being continuous with these cavities. 



The condition of the eyes and orbits, so regarded, may, 

 therefore, be looked upon as very " tell tale " by the 

 observant physician and surgeon, and as affording valuable 

 information in the work of diagnosis. Moreover, such 

 questions arise out of the foregoing as whether, or not, 

 tapping might be desirable and practicable periorbitally, or 

 lumbar puncture resorted to as a curative agency, as a 

 means of relief, or for diagnostic purposes. 



In the light of these views some obscure problems 

 relating to the origin and progress of such diseases as 

 rheumatism, gout, influenza, ague, etc., seem to have a 



