CILIARY MOVEMENT 



553 



membrane of the nares, mouth, pharynx, oesophagus, 

 stomach, and lungs, by which much of their ciliated 

 epithelium is modified or abolished, but the discharge 

 from within the cerebro-spinal cavity still continues to 

 be aided by it, until the clogging effects of advancing 

 life gradually usurp the conditions of early freedom and 

 physiological activity so far as ciliary agency is concerned 

 by which time the processes of mastication, insalivation, 

 pituitarisaticn, and deglutition are capable of effecting the 

 same end by more decidedly musculo-mechanical means 

 and superadded digestive agencies. 



It is noteworthy, too, that such inter-current lymph, 

 channels, as the lachrymal sacs and nasal ducts and the 

 Eustachian tubes become lined with a ciliary epithelium,, 

 so as to facilitate the movement of fluids, with dissolved 

 or suspended materials, through passages, or structures,, 

 which are not contractile, and hence are merely passive 

 and vehicular, in relation to their circulating contents. 



Viewed thus, it becomes abundantly obvious, and in 

 fact absolutely evident, that no such thing as a cerebro- 

 spinal "shut sac" can possibly exist, but, on the contrary, 

 that a circulatory regime of a most apparent and " abso- 

 lutely adapted " character subsists throughout the whole 

 nervous system, by means of which the great desiderata 

 of fluid mechanical support, equalisation of intra-cranio- 

 spinal pressure, and physiological hygiene, are simul- 

 taneously secured and maintained, quite " in keeping " 

 with the requirements of the great central or blood 

 circulation, and the many other minor and less apparent 

 circulations to be found throughout the human organism. 



What more ideally adapted means for the keeping clear 

 of the cerebro-spinal lymph " highways and byways " than 

 the " sweeping apparatus " of an epithelial lining mem- 

 brane, the ciliary processes of which are in continuous 

 movement, with the result of regular forward progress 

 of the circulating fluid, and, it probably may be, its retro- 

 grade movement, when circulatory progression becomes 

 stayed or reversed? Outside the "sphere of influence" 

 of the heart's impulse, when circulation is reduced to a 

 great extent to " vegetative " proportions and methods, 

 we see at work a most wonderful array of circulatory 



