only due to lack of opportunity, but to an inborn constitutional defect.

Further study has shewn this defect to be hereditary—the parents or grandparents of such people shew defective intelligence, and their offspring are likely to do the same; indeed, if two mentally defective people marry it is fairly certain that their children will all be mentally defective.

There are, however, no sharply defined classes of intelligence; just as the mentally defective are in many grades, so ordinary men and women vary from low or average intelligence up to outstanding cases of genius or capacity.

By the newer methods of mental testing it has been shewn that children of various classes of the community, as well as men and women of different races, can be grouped according to their intellectual capacity, and that no educational facilities will develop that capacity beyond a certain point.

Professor W. McDougall, F.R.S., in his most useful and interesting book on National Welfare and National Decay, reaches the important conclusion "that innate capacity for intellectual growth is the predominant factor in determining the distribution of intelligence in adults, and that the amount and kind of education is a factor of subordinate importance." He claims that the evidence is overwhelming as to the validity of the results obtained by mental testing.

A few examples of experimental work given in Professor McDougall's book will suffice to show the trend of these results.

Tests of intelligence were carried out on recruits for the American Army, white and coloured, and they shewed marked superiority of the white race.

A special test was carried out in Oxford by Mr. H.B. English, who compared the capacity of boys in a school attended by children of the intellectual classes with that of boys in a very good primary school, whose fathers were shop-keepers, skilled artisans, etc., coming from homes which were good, with no sort of privation. The result showed marked superiority of the sons of intellectual parents. Mr. English concludes that the children of the professional classes, between 12 and 14 years of age, exhibit very marked intelligence, and he is convinced that the hereditary factor plays an altogether predominant part.

In another experiment, Miss Arlitt, of Bryn Mawr College, tested 342 children from primary schools in one district, who were divided into four groups:—

Marked differences between the groups were shewn. The intellectual capacity was represented by figures as follows:—