Notes, correspondence and background material. The distinction between 'Intelligence' and 'IQ and Race' is far from clear though it can usually be substantiated by designations given to the material itself. The items grouped under 'Intelligence' deal with attempts to define and measure the concept of intelligence, genetic variables and environmental factors. A substantial proportion (MS. Darlington c. 29/D.129-D.134) is on the work of Cyril Burt, a leading figure in the promotion of intelligence testing whose data was subsequently discredited.