112 HAND-BOOK OF PHYSIOLOGY. 



claim to be considered as an organ of the mind, or as the seat of sensation 

 or voluntary power. These are connected with parts to be afterward 

 described. 



PONS VABOLII. 



Structure. The meso-cephalon, or pons Varolii (vi, Fig. 326), is 

 composed principally of transverse fibres connecting the two hemispheres 

 of the cerebellum, and forming its principal transverse commissure. But 

 it includes, interlacing with these, numerous longitudinal fibres which 

 connect the medulla oblongata with the cerebrum, and transverse fibres 

 which connect it with the cerebellum. Among the fasciculi of nerve- 



FIG. 326. Base of the brain. 1. superior longitudinal fissure; 2, 2', 2', anterior cerebral lobe- 3 

 fissure of Sylvius, between anterior and 4,4',4", middle cerebral lobe; 5, 5', posterior lobe- 6 medulla 

 oblongata; the figure is in the right anterior pyramid: 7.8,9,10, the cerebellum- + the inferior ver- 

 miform process. The figures from I. to IX. are placed against the corresponding cerebral nerves- 



* *" 



fibres by which these several parts are connected, the pons also contains 

 abundant grey or vesicular substance, which appears irregularly placed 

 among the fibres, and fills up all the interstices. 



^unctions. The anatomical distribution of the fibres, both trans- 

 verse and longitudinal, of which the pons is composed, is sufficient evi- 

 dence of its functions as a conductor of impressions from one part of the 

 cerebro-spinal axis to another. Concerning its functions as a nerve- 

 centre, little or nothing is certainly known. 



