VESSELS AND NERVES OF CEREBRAL MEMBRANES. 471 



Lymphatics are said to have been demonstrated by Fohmann and 

 Arnold in the pia mater, on the surface both of the cerebrum and 

 cerebellum, and in the choroid plexus an observation needing 

 confirmation. 



Nerves also are found in the membranes of the nervous centres. 

 The dura mater of the cerebrum has nerves (twigs of the eighth 

 pair), pretty nearly following the course of the meningeal arteries, 

 and especially upon the middle meningeal. A twig from the third 

 branch of the fifth pair is distributed principally to the bones. 

 Another from the fifth pair is called the nerve of the tentormm 

 cerebelli, and goes to the larger sinuses of the dura mater. (Pappen- 

 heim.) Neither Kolliker nor Purkinje has detected any nerves in 

 the theca vertebralis ; though they occur in the periosteum of the 

 vertebral canal, and on the arteries going to the vertebrae and the 

 cord. 



The arachnoid contains no proper nerves, but the vessels pene- 

 trating it do, especially at the base of the brain. The pia mater of 



Fig. 313. 



Fig. 314. 



Fig. 343. Vessels of the cerebral substance of the sheep, from one of Gerlach's injections; a, of 

 the gray; 6, of the white substance. (KiJttiker.) 



Fig. 314. Two terminal arteries from a branch on the surface of a convolution of the cerebrum, 

 and dipping vertically inwards ; and exhibiting the mode of origin and distribution of capillaries in 

 the gray cortical layer. From an injected specimen. (Magnified 30 diameters.) 



