A PRELLAIINARY DETERMIXATIOX OF THE PART 

 PLAYED BY MYELIN IX REDUCIXG THE WATER 

 COXTEXT OF THE MAMMALIAN NERVOUS SYSTEIVI 

 (ALBINO RAT) 



H. H. DONALDSON 

 From The Wislar Institute of Anatomy and Biology 



ONE CHART 



It is a familiiir fact that there is a progressive loss of water in 

 the brain and spinal cord with advanchig age. This is illus- 

 trated for the albino rat in Chart 1. 





f^SiBSii^ 



rrn^-t: 



T tr^iiu:::.'!:: v. :; ir :tr:jirn trr::: : it: 



-n^ 



JX 



Chart 1 Showing the percentage of water on age in the central nervous 

 system of the alljino rat. The upper graph gives the values for the water in the 

 brain as determined by the formuhis (Hatai. in 'The Rat,' Donaldson, '15). The 

 lower graph gives the corresponding values for the spinal cord, determined in the 

 same way. 



The small black dots indicate the observed values for the several age groupa 

 for the brain, and form the data for the formulas. The small black triangles 

 have a like value in relation to the spinal cord. 



443 



