VESSELS OF THE BRA IX AND CORD. 165 



short vessels pass outwards and slightly backwards to the out^r 

 border. The connective-tissue between these vessels is pushed down 

 into the cavity ; in this manner one obtains a double row of flattened 

 villous-looking bodies, which frequently have their tips pigmented. 

 The under surface of the plexus is clothed with flattened, ciliated 

 epithelium. 



On either side of the pituitary body is another small venous 

 plexus (Plexus lateralis, Schobl); it communicates above with the 

 posterior angle of the choroid plexus of the third ventricle ; exter- 

 nally, with the internal jugular vein ; and internally with its fellow 

 of the opposite side by more or less irregular transverse vessels, 

 which, together with a median vein from the fissure between 

 the cerebral hemispheres, form an irregular circvhts renosvz around 

 the pituitary body. These plexuses receive blood from the lower 

 part of the cerebral hemispheres, the thalamencephalon, the optic 

 lobes, and from the pituitary body. The veins of the spinal cord 

 open into the dorsal, vena spinalis posterior (Fig. no spp), which 

 bifurcates at the posterior angle of the fourth ventricle, one division 

 passing to either side and forming, as already described, the outer 

 border of the choroid plexus ; anteriorly it opens into the internal 

 jugular vein (Fig. noj'i). 



The blood-vessels, both arteries and veins, are irregularly pig- 

 mented, both on the surface and in the interior of the central 

 nervous system; those of the cerebral hemispheres and olfactory 

 lobes have very little or no pigment. 



