Col. James Earle Ash, 101, who headed the Armed Forces Institute of Pathology here during World War II and who published a noted compendium of tropical diseases that was widely used by the American military and others, died of cardiopulmonary arrest March 24 at his home in Bethesda.

Col. Ash was commissioned in the Army Medical Corps in 1916 and he retired from it in 1947. He served eight years at the Sternberg Army Hospital in Manila, and while there he became an authority on tropical diseases. He also was the pathologist at Letterman Army Hospital in San Francisco and at Walter Reed Army Hospital.

When he retired from the Army, Col. Ash became the first scientific director of the American Registries of Pathology. He then organized the pathology department at Suburban Hospital and was the head of it until 1963. In the meantime, he established a private pathology laboratory in Rockville. He remained active in it until he finally stepped down in 1979.

Col. Ash served twice as chief of what is now the Armed Forces Institute of Pathology, which is located at the Walter Reed Army Medical Center. When he first went there, it was called the Army Medical Museum, and the institute still maintains a museum. The second of his tours in that post extended from 1937 to 1947, and Col. Ash is credited with transforming the institute into a center for the study of disease that enjoys a world reputation.

His work at the institute included organizing a centralized system for reviewing and filing all military autopsies and surgical specimens. With the support of the National Research Council, he added a system of registries of material from civilian sources, including one on X-ray patterns of disease and another on animal diseases. The latter was maintained for the information it could provide on human ailments.

From these sources Col. Ash developed a series of atlases, or guides, covering each of the clinical specialties developing in medicine. These sources also provided the material for the illustrated atlas of tropical diseases that he published during World War II.

Col. Ash was born in Philadelphia. He took his medical degree at the University of Pennsylvania in 1905. He conducted a general medical practice in Philadelphia until 1910, when he went to Vienna to study pathology. From 1911 to 1916, he was a member of the pathology department at Harvard Medical School. He then went into the Army.

Col. Ash's military decorations include the Legion of Merit. The 50th American Microscopic Pathology Seminar was dedicated to him to honor his 100th birthday.

Col. Ash's marriage to the former Marguerite Hal-Brown ended in divorce. A son by that marriage, James Earle Ash Jr., died about 1929. A daughter of that marriage, Signe Ash McClellan, died in 1984.

Survivors include his wife, Mary Catherine Ash, whom he married in 1947, of Bethesda.