THE NERVE ELEMENTS. 



159 



TABLE 35. GIVING ESTIMATES OF THE VOLUME OF THE 

 CENTRAL NERVOUS SYSTEM ENCEPHALON AND SPINAL 

 CORD AT DIFFERENT AGES. 



Three-quarters of this volume is assumed to represent the 

 nerve elements proper. For the first two records I am indebted 

 to Professor F. P. Mall. The third is estimated. 



In the foregoing table the number of cu. cm. in the 

 central system at different ages have been given, and 

 then three-fourths of this taken as the volume of the 

 nerve tissues proper, assuming that the other fourth is 

 accounted for by the supporting and nutritive struc- 

 tures. 



Meynert computed that there were 1,200 millions of 

 ganglion cells in the cortex of the hemispheres, and 

 that there were some ten millions of large cells in the 

 cortex of the cerebellum. Adding to them the cells in 

 the basal ganglia, the small cells everywhere, together 

 with all those in the spinal cord, 3,000 millions would 

 be a moderate estimate of the total number in the 

 central system. Taking 3,000 millions as a working 

 figure, the volume of the average cell (body and pro- 

 longations) in the central systems of an adult man is 



Specific gravity, ro25. 



Specific gravity, i'O35. 



