United States Civil Service Commission announces examination for student trainee, $3,175 and $3,415 a year (grades GS-3 and GS-4) (for Departments of Agriculture and Interior, and Bureau of Census), optional fields, accounting, agricultural economics, biological and plant sciences (biology, horticulture, plant physiology, plant pathology, soil science), entomology, home economics, plant pest control, statistics, agricultural, general, announcement 84B.