The Lethal Action of Sunlight Upon Bacteria in Sea Water

Although our knowledge of the distribution and activities of marine bacteria is woefully scant, it is recognized that these microOrganisms play an important role in the biology, geology, and chemistry of the sea (cf. Bavendamm, 1932; Benecke, 1933; and Waksman, 1934). There are several factors which are known to influence the distribution of bac teriain the sea,but so complex isthe problem thatitisnecessaryto considereach factorsinglyin orderto evaluateitssignificance. Ithas been statedfrequentlythatthe lethalactionof sunlightupon bacteriahas a profoundeffectupon theirvertical, diurnal,and seasonal distribution.For example,Fischer(1894) found more bacteriain the North Atlanticat sunrisethan in the afternoon,and Schmidt-Nielson (1901) attributedto the killingactionof sunligh the differencebe tween 26 bacteriaper cubiccentimeterof surfacesea water and 420 per cubic centimeter at a depth of 25 meters. Similarly, Bertel (1912) noted thatduring May and June, a periodof intenseinsolation, the