Pearl, Correlation in Brain- Weight. 479 



supra. Numerous otlier uses to which they may be put are 

 illustrated in the complete paper. 



In using these equations the following points, should be 

 kept in mind : 



(a) The equations give the probable mean brain-zveight of 

 an array of given t}pe in respect to other characters They 

 are therefore not to be depended on to predict individual brain- 

 weights. , 



(b) They are strictly ////;'«;'««'«/ equations. 



(c) The male and female equations are not interchangea- 

 ble. 



(d) On material comprising individuals between the ages 

 of 15 and 50 the equations based on the "young" series should 

 be used. 



II. Concluding Rejiiarks. In concluding I desire to call 

 attention to the following points. 



(a) The essential agreement between the four different 

 races studied in respect to the biometric constants for variation 

 and correlation in brain-weight is noteworthy. This agreement 

 in the statistical constants from four series of data so diverg- 

 ent in their origin as those treated in this work cannot rea- 

 sonably be held to be fortuitous. It can only mean that there 

 are definite laws underlying variation in the weight of the brain 

 which are not fundamentally different from the laws of variation 

 for the other characters of the body. 



(b) There is no evidence that intellectual abihty and the 

 weight of the brain are in any degree correlated in normal indi- 

 viduals. 



(c) There is need for more and larger collections of brain- 

 weighings, in which close attention is paid to the homogeneity 

 of the material, and to the recording of other subsidiary data in 

 addition to brain-weight. In comparison with the series of 

 brain-weighings available at present, a collection which should 

 record the following facts would be almost ideal. 



1. Brain-weight, by the standard method. 



2. Race. In this the more essential detail given the better. 



3. Country of residence during adult life. 



