Leon Paul Weiss, 87, department chairman at Penn

Leon Paul Weiss, 87, of Merion, former chairman of the department of animal biology at the School of Veterinary Medicine at the University of Pennsylvania, died Tuesday, Oct. 16, at home surrounded by his wife and children. He had been in ill health and died of pneumonia.

Dr. Weiss was a medical doctor who spent his career in research, teaching, and writing, focusing his work on cells and tissues of the immune system and the hematopoietic organs, which produce blood.

After serving in the Army Medical Corps, Dr. Weiss taught at the medical schools at Harvard and Johns Hopkins Universities. He joined the veterinary faculty at Penn in 1976.

He was editor for many years of a leading textbook, Histology, and illustrated many of his own pen-and-ink drawings of cells and tissue structure as seen through an electron microscope.

Dr. Weiss also taught histology - the study of the anatomy of cells and tissue - at Penn's medical school. His daughter Marisa, now director of breast radiation oncology at Lankenau Medical Center, was a student in his class in medical school.

"He was an amazing professor," she said. "He was famous for explaining complex subjects in simple ways."

Dr. Weiss helped design the medical school curriculum at his alma mater, the City College of New York, and helped found two programs at Penn - the Center for the Interaction of Animals and Society, and the Center for Aquatic Animal Medicine.

He also conducted research on malaria, work he continued after retiring from Penn at 83. He was a natural fit for studying the disease, his son Philip said.

"It kills so many people and it's blood-borne," he said.

Dr. Weiss was born in Brooklyn in 1925, the son and grandson of Hungarian immigrants. He entered the Long Island College of Medicine in 1945, and met his future wife, Ellen Tarter Fishbein, the next year at the Morningside Heights subway stop.

The family described Dr. Weiss as an introvert, but his wife said he managed to pick her up that day.

"His first and last, ever," she said.

In addition to his wife, son, and daughter, Dr. Weiss is survived by four other children, Stephen, Alice, Nathaniel, and Eve, as well as their spouses; and 12 grandchildren, Adam, Aaron, Elias, Daniel, Ethan, Henry, Isabel, Madeleine, Sara, Ella, Owen, and Livia.

A memorial service will be held at 2 p.m. Saturday, Nov. 24, at 370 Aubrey Rd., Wynnewood. Another memorial will be held in the summer at the Marine Biological Laboratory in Woods Hole, Mass.