Paul S. Conger, 82, a botanist emeritus of the Smithsonian Institution who specialized in the study of diatoms, a source of food for all kinds of marine life, died Sunday at George Washington University Hospital of injuries suffered in an accident Aug. 9.

Washington police said Mr. Conger was crossing Pennsylvania Avenue at 10th Street NW when he was struck by a bicycle. He suffered a fractured skull when he fell to the pavement and never regained consciousness. Police said no charges were filed in the case.

Mr. Conger was on his way home from work at the Smithsonian when the accident occurred.

Mr. Conger was born in Waukesha, Wis., and grew up in Prairie du Sac, Wis. He graduated from the University of Wisconsin at Madison and then earned a master's degree there in entomology, the study of insects.

In 1921, he moved to Washington and joined Dr. Albert Mann at the Museum of Natural History in the study of diatoms. In addition to being an important part of the food chain for marine life, diatoms, which are algae, have many other uses. Lightweight bricks can be made of them. In 1953, Mr. Conger announced a method for using diatoms for detecting impurities in food products.

From 1921 until 1932, when Dr. Mann died, Mr. Conger's work at the natural history museum was sponsored by the Carnegie Institution of Washington. After Dr. Mann's death, it was carried on under the Smithsonian.

In addition to his work at the museum, Mr. Conger did field work at the Oceanographic Institute at Woods Hole, Mass., at the Carnegie laboratory on the Dry Tortugas off the coast of Florida, and at the Chesapeake Biological Laboratory at Solomon's Island, Md.

He retired in 1967 and was named a botanist emeritus.He also taught at George Washington University.

Mr. Conger was a member of the American Association for the Advancement of Science, the Washington Academy of Sciences and the Phycological Society of America. He published a number of papers in technical journals.

Survivors include his wife, Edith Elliott Conger, of the home in Chevy Chase; a son, Norman, of Huntington Beach, Calif.; two daughters, Nancy Louise, of Washington, and Alice Patterson, of Manhasset, N.Y., and six grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the National Kidney Foundation, 1825 Connecticut Ave. NW, Suite 301, Washington, 20009.