30 MAL-NUTRITION AND THE TEACHER'S 



between mental capacity and the state of nutrition. This 

 is precisely the result obtained in the Galton Memoir. 



A further point deserves consideration. In addition to 

 * mental dullness ' three classes of defects are considered, 

 developmental defects, nerve signs, and bad nutrition. The 

 association of these classes of defects with * mental dullness ' 

 is nearly the same. Thus, in cases of developmental defects, 

 38-3 % of the boys and 41-5 % of the girls are ' mentally 

 dull ' ; in cases with ' nerve signs ', 40-1 % of the boys and 

 42-4 % of the girls are ' mentally dull', while in cases of ' low 

 nutrition ' the percentages are 39-0 and 40-6 respectively. 

 If we now classify children as having no defect, one, two, or 

 three classes of defects, we can find the percentage of mentally 

 dull in each class. These results are given in Table V. 



V. TABLE SHOWING THE PERCENTAGE OF CHILDREN WHO 



ARE 'MENTALLY DULL' AMONG CHILDREN WHO HAVE 



o, I, 2, OR 3 CLASSES OF DEFECTS. 



We see from this that the ' piling up of defects ' makes 

 comparatively little difference in the percentage of children 

 who are 'mentally dull', and among the girls of the 1888 

 investigation, no difference at all. Again, if we take cases 

 with low nutrition, but neither with developmental defects 

 nor nerve signs, the percentages who are mentally dull are 

 54-1 (boys) and 66-7 (girls) for the 1888 investigation, and 



