GROWTH OF THE CEREBRAL CORTEX 



575 



tal region, show a relatively rapid development in the first phase, 

 attaining at the end of that phase 2.45 times the thickness at 

 birth, while at the end of the second phase they have attained 



TABLE 10 



Giving for the three sections, the thickness of the cerebral cortexin eachlocality at the 

 beginning and the end of each of the three phases and also the percentages of gain 

 in thickness during each phase. The data on thickness are taken from tables 6, 

 7 and 8. The average percentage gain in thickness for each section was computed 

 by using the average of the values for the observed thickness for each locality. The 

 general average percentages in the last line of the table ivere obtained by using the 

 mean of the averages for thickness in the three sections, giving the average values 

 for each sqction the same statistical weight 



1 As the observed values at these localities in these groups have fallen below 

 those in the foregoing and the following groups, I used in this table the values 

 based on the average of all three groups. 



