82 Ar/ierlcau Statistical Association. 



The curves of growth of the two sexes being recognized as 

 so distinctly different, it is of interest to inquire what practi- 

 cal application can be made of the knowledge thus acquired. 

 The first question which suggests itself is: How far should 

 this difference in the rate of growth be allowed to modify the 

 system of mental training to which the children of the two 

 sexes are subjected? The physical conditions upon which 

 the manifestation of mental activity depend are too little 

 understood, and the whole question is too complicated to be 

 discussed in this connection, but it seems to be almost self- 

 evident that at those periods when the forces of the organism 

 are engaged in producing rapid growth and development of 

 the physique, the requirements in the way of mental effort 

 should be reduced. The fact that these periods occur at 

 different ages in the two sexes may therefore be regarded 

 as an argument against the co-education of boys and girls, 

 except during the earlier years of life in which rates of 

 growth are practically the same, i. c, up to ten or eleven 

 years of age. How much importance is to be attached to this 

 argument is a question which demands for its solution an 

 extended series of observations on the annual growth in 

 height and weight of a large number of individuals, taken in 

 connection with a record of their mental progress. 



Effect of Race on Size and on Rate of Growth. 



An examination of Tables Nos. 1 and 2 shows that boys 

 and girls of American parentage are, almost without excep- 

 tion, both taller and heavier than children of the same age 

 and sex whose parents are of other nationalities. The curves 

 on Plates VI and VH illustrate this fact for children of 

 American and Irish parents. It has not been thought desir- 

 able to construct curves for the other nationalities, owing to 

 the irregularities which they would necessarily present in 

 consequence of the small number of observations. 



In considering this result the question naturally suggests 

 itself, How far are the superior dimensions of children of 



