HOUSTON (AP) — The Texas prison system should hire Negroes in proportion to the per centage of blacks held in prison, the local NAACP director told officials of the Texas Department of Corrections Monday. The Rev. C. Anderson Davis, director of the Houston chapter of the NAACP, said more than 40 per cent of the ‘state’s prison inmates are black but only three per cent of the prison employes are Negroes.