Chap. XIX] 



THE NERVOUS SYSTEM 



387 



no malign influence on sensory nerves nor upon the intellect. 

 The motor system is, however, profoundly deranged. IVIotion 

 is itself not destroyed, but coordination is so interfered with that 

 movements of one part of the body cannot be adapted to other 

 parts. 



Pigeons deprived of the cerebellum will fly if thrown from a roof 



XT' 

 XII- 



SYLVIAM 



FISSURC 



lion PER- 

 ED SPACE 



INFUNOI* 

 BULUM 



POSTEPIOR PER- 

 FORATED SPACE 

 CRUS CEREBRI 



( 



'i mSm I'm iiiii— imA W iT^ 



wi..i JZ_J_ T1...!II1!1L^\«— ( 



CEREBELLUM 



Fig. 183. — Under Surface of the Brain, showing the Superficial 

 Origins of the Cranial Nerves. The Roman numerals indicate the nerves. 

 (Gerrish.) 



but the delicacy of the coordination being lost, they turn a series 

 of somersaults in the air and soon fall to the ground. 



Pons Varolii. - — The pons Varolii, or bridge of Varolius, lies in 

 front of the upper part of the medulla oblongata. It consists 

 of interlaced transverse and longitudinal white nerve-fibres 

 intermixed with gray matter. The transverse fibres are those 

 derived from the middle peduncles of the cerebellum and, as 

 already stated, serve to join its two halves. The longitudinal 

 fibres join the medulla with the cerebrum. 



Functions of pons Varolii. — The pons is a bridge of union be- 

 tween the two halves of the cerebellum and a bridge between 



