50th annual report of the Gorgas Memorial Laboratory, fiscal year 1978 : communication from the President of the Gorgas Memorial Institute of Tropical and Preventive Medicine, Inc. submitting the 50th annual report of the Institute and the financial statement for fiscal year 1978, pursuant to Section 3 of the Act of May 7, 1928, as amended. (U.S. G.P.O.,, 1979)