V. S. Government

Operation of screen chamber, grit chamber, primary clarifier, aeration tanks, secondary clarifiers, and other procedures in activated sludge process. Aerial and over-all ground views and graphic flow diagrams. (CDC-9-033.5; 41 slides, 2x2 in.) Aquatic Plants Associated With Anopheles Breeding Areas U.S. Public Health Service, 1949. Aquatic plants found in environs of representative breeding places of Anopheles quadriculatus, crucians and punctipennis in Southeastern states. Arranged according to system of Engler and Prantl. (CDC-5-092; 169 slides, color, 2x2 in.)