4OO 



BIOLOGICAL PHYSICS 



The first pair of cephalic nerves (Fig. 130), in like 

 manner, originate from hollow extensions of the fore-brain, 

 which terminate over the cribriform plates of the ethmoid 

 bone, where they carry with them their meningeal coverings, 

 separated by their intervening spaces, and fluid contents, 

 the latter of which they discharge, or distil, into the nasal 



e.sJl 



a.p 



FIG. 130. ORBITAL SURFACE OF THE FRONTAL LOBE, AND ISLAND OF 

 REIL. Natural size. (Turner.) 



The island (7.7?.) is exposed by removal of the apex of the temporo sphenoidal lobe. 

 T.S., cut ridge of this lobe; a.p.s, anterior perforated space; a.s.R., p.s.R., 

 anterior and posterior limiting sulci of the island ; op, operculum of the island. 

 tr.s., tri-radiate sulcus ; z.o.c., a.o.c., and p.o.c , internal, anterior, and posterior 

 orbital convolutions; 0(f.s., end of the olfactory sulcus; olf.tr., olfactory tract, 

 bifurcating behind into the two roots inner and outer ; m, middle root or tuber 

 olfactorium. 



passages through the glandular mechanisms of their lining 

 mucosa, thus allowing of their performing the double func- 

 tions of sense organs and lymph excretory agencies. This 

 mention of nasal cerebro-spinal lymph excretion brings to 

 our mind that we might here take another opportunity of 

 enumerating the various channels of exit, or excretion, with 

 which we have had occasion to deal in our inconsecutive 

 treatment of the great subject of cerebro-spinal lymph 

 disposal. Besides the nasal excretion of cerebro-spinal 



