JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Association of Schools of Public Health is collaborating with JSTOR to digitize, preserve and extend access to When exposed to running sea water, the clam uses its own filtering system to cleanse itself of sewage bacteria ingested in polluted waters. How this is accomplished was demonstrated in a series of experiments conductedl by the Shellfish Sanitation Laboratory. soft clam, Hya arenaria, have become seriously depleted. Attempts made by biologists (1) to increase clam populations to their former abundance by establishing clam farms and reseeding depleted areas have met with little or no success. However, large supplies of clams in areas which are polluted with domestic sewage are available.The possibility of ridding shellfish of undesirable bacteria, has been given some attention ever since epidemiological evidence indicated that shellfish from waters subject to fecal pollution were responsible for enteric disea,se (2). That polluted shellfish can be made safe for human consumption by the process of purification ha,s been a,dequately demonstrated by Fabre-Domergue (3), Wells (4), and Dodgson (5).Purification is a mechanical process effected by the physiological functioning of the shellfish in clean water. When shellfish are feeding, the gills act as a filter to strain out some of the material that may be brought in by the water which passes through them. If this water contains sewage, some of the micro-organisms in it are entrapped in the mucus on the body of the shellfish and transferred to the alimentary tract. Some of these are perhaps utilized as food (6) and the others discharged from the body in the form of feces and pseudofeces. When shellfish from polluted water are placed in clean water, the sewage bacteria are eliminated from the shellfish, and, since no more are ingested, purification is accomplished. Two purification processes, based on the ability of shellfish to cleanse themselves, have been evolved:Natural purifieation or relaying. Shellfish from polluted areas are transplanted into clean waters and allowed to purify themselves. This method of natural purification is widely used in the oyster industry. However, many biological factors combine to make it generally infeasible for use with soft clams.Artificial purification or cleansing. Shellfish from polluted areas are placed in tanks which are filled with water that has been sterilized by filtration, chlorination, or by ozone. The water Mr. Arcisz is bacteriologist at the Public Health Service Shellfish Sanitation Laboratory, Pensacola, Fla., and Mr. Kelly is chief of the laboratory. Other studies in this series of reports on shellfish experiments conducted by the laboratory have appeared in