QUANTITATIVE STUDY OF THE PURKINJE CELLS 



247 



TABLE 4 



cerebral hemispheres are much below weight, which further 

 indicates that the cause of the arrest took effect after birth. 



An examination of the cells reveals on the anatomical side at 

 least a reason for the defect. Many cells are atrophied and are 

 so far degenerated that they cannot have any functional value. 

 Other cells are less degenerated and some are apparently normal, 

 but others have completely disintegrated and have been ab- 

 sorbed. This is clearly a case of postnatal degeneration, but 

 even so, it represents the exception rather than the rule among 

 subnormal individuals. The entire case history shows this. 



In this as in the other cases, then, we find that in low-grade 

 mental defectives there is a distinct deficiency, either numerically 

 or cytologically, in a large percentage of the Purkinje cells. 



SENESCENCE 



It is a familiar fact that very old people usually suffer a con- 

 siderable loss of motor control. The results of counts made on 

 five cases of senescence of different ages are given in table 5 and 

 show how the cells drop out with increasing age. 



The results of table 5 are shown graphically in chart 1. The 

 value for the normal is based on table 1 and the starting-point 

 for the drop in the curve is placed somewhat arbitrarily at the 

 age of forty years. 



In connection with this curve it is interesting to note that it 

 is based on the cerebella of two men of superior mentality, on 

 one negro male autopsied in a general hospital, and on one white 

 male and one white female dying at extreme old age in hospitals 



THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 30, NO. 2 



