244 



NERVOUS SYSTEM. 



middle enlargements (100. c. e?,) are conspicuous, and of a 

 lengthened form from the magnitude and number of the 

 nerves which proceed from them to the sacral and atlantal 

 extremities ; the cauda equina, ( 1 00. a, b,) is of great length 

 from the high and sudden FIG. 100. 



termination of the spinal 

 chord; the motor roots (100. 

 I, /,) and anterior columns 

 are smaller than the sensi- 

 tive, as in other animals, and 

 the ganglia of the posterior 

 or sensitive roots (100. ,) 

 of the spinal nerves are here 

 larger than in other mam- 

 malia. The medulla oblon- 

 gata, though comparatively 

 small, has its component 

 fasciculi most deeply marked, 

 and the quantity of internal 

 ganglionic matter in the 

 course forwards of these 

 white fibrous fasciculi, cor- 

 responds with their great 

 development in the human 

 cerebral and cerebellic he- 

 mispheres, where the convo- 

 lutions (100. g,) and laminae, 

 (100. h, i,) surpass in num- 

 ber and depth those of al- 

 most all inferior animals, 

 but where the use or func- 

 tion of any filament has not 

 yet been determined. The 

 great systems of converging 

 fibres which cross the median 

 plain, which form the corpus 

 callosum, the tuber annu- 

 lare, and the various smaller 

 commissures, and which have 

 appeared to some as conti- 

 nuous with the diverging or 



