AS THE BIOLOGIST SEES IT 



of mental age and intelligence quotient, 

 certain general categories of mental ca- 

 pacity or incapacity have been established 

 and are now commonly used by psychol- 

 ogists. At bottom is the category feeble- 

 minded, then, in ascending order, border- 

 line, dull-normal, average-normal and 

 superior. 



Much special study has been given 

 feeble-mindedness by students of heredity 

 in the last decade and it has been fairly 

 satisfactorily proved that this mental 

 condition is not only an inherited con- 

 dition, but that it may be looked on as a 

 unit human trait following the general 

 Mendelian order as regards its mode of 

 inheritance. If this is really so and it is 

 hardly any longer open to doubt it has 

 obviously a most important significance 

 in connection with the whole problem 

 of education. It must make us face 

 squarely the situation that there are 

 limits to the educability of certain in- 

 dividuals and that we should somewhere 

 call a halt on the vain efforts we are 

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