INCREASE OF THE BRAIN IN WEIGHT. Ill 



TABLE 21. COMPARING THE PROPORTION OF WATER AND OF 

 SUBSTANCES EXTRACTABLE BY ETHER IN THE FIBRES OF 

 THE CALLOSUM OF THE NEW-BORN AND THE ADULT. (Con- 

 densed from the Observations of Schlossberger.} 



PERCENTAGE OF 



WATEK AT BIRTH. IN THE ADULT. 



89-48 ............ 70'60 



89-60 ............ /O^O 



8979 ............ 70-68 



PERCENTAGE OF 

 ETHER EXTRACT AT BIKTH. IN THE ADULT. 



378 ............ 15*03 



378 ............ J5'32 



Observations made on the growth of any part made by 

 the "general" method are of little use in determining 

 the age at which growth in the individual ceases, be- 

 cause, so long as any of the individuals grow the curve 

 will rise, and there is no way to determine whether the 

 rise is due to a slight growth in many, or a greater 

 growth in a few. Further than this it is not probable 

 that the cessation occurs at the same age in all classes 

 of the community, and we might fairly expect that it 

 would be continued for the longest time in those most 

 favoured. To this conclusion the observations by Venn 

 in England directly point. 1 Suffice it to say that Venn 

 measured the heads of students at Cambridge through- 

 out the entire student period, and found that the head 

 increased in height, breadth, and length during this 

 time. From this it is inferred that the brain also 

 increased, and it is highly probable that such is the case. 

 The observations of West, made in the Worcester 

 (Mass.) Schools, 2 show a steady growth in the length 

 and breadth of the head between the ages of five and 

 twenty-one years. They also show between the ages of 

 eleven and thirteen years an approximation of the curves 



1 Venn, Nature, 1890. 



2 West, Archiv.f. Anthropol.^ '1893. 



