W. Koch and M. L. Koch 



443 



40 50 60 70 80 90 100 110 120 130 140 150 



170 180 190 200 210 220 



CHART 1. Shows the absolute weight in milligrams, of the constituents 

 of a single brain of the albino rat at different ages. (Age in days along 

 the abscissa; mgms. on the ordinate.) 



CHART 2. Shows the rate of increase of the different constituents of 

 the brain of the albino rat at different ages, taking the amount of each 

 constituent in the brain at birth as unity. (The ordinate shows how many 

 times the weight of each constituent has increased over its amount at 

 birth at the age plotted on the abscissa.) 



