LESSER CEREBRO-SPINAL LYMPH 125 



Here, as in the auditory organisms, the cerebro-spinal 

 fluid seems to perform many very important offices during 

 its passage through, and presence in, the optic organs, 

 ingress to which it obtains along the subdural and subarach- 

 noid spaces (Fig. 47), where they leave the cranial cavity 

 to enter the orbits along the neurilemmar inter-spaces 

 surrounding the optic nerve as well as along the sheaths 

 of the blood-vessels which pass from within the skull to 

 these organs, and which are also accompanied by meningeal 

 sheaths. Here, moreover, is afforded by the plentiful 

 presence of the cerebro-spinal fluid and accumulations 



FIG. 48. MEIBOMIAN GLANDS OF THE LEFT EYELIDS AS SEEN FROM 



BEHIND. 



, a, palpebral conjunctiva ; i, lachrymal gland ; 2, openings of seven or eight of its 

 ducts ; 3, upper and lower puncta lachrymalia ; 6, 6, ends of the upper and lower 

 Meibomian glands, of which the openings are indicated along the margins of the 

 eyelids. 



of fatty post- orbital material, two padded, or cushioned, 

 chambers in which shock is deadened and freedom of 

 movement secured, so that the two most delicate sense 

 organs can perform their functions without " let or 

 hindrance." Here also, if we patiently follow the windings 

 of the cerebro-spinal lymph circulation of the eyes, we find 

 a succession of spaces and channels leading into the very 

 interior of these organs, and perceive that the vitreous 

 and aqueous humours are but two great pools, or cisterns, 

 (Fig. 46) of that fluid, continuous with and physically 

 apart from specialised organic matters indistinguishable 

 from it ; and, therefore, to " all intents and purposes " 

 drawn from and mostly dependent upon it ; moreover, we 



