both stähelin's parents were medical doctors. after preparatory school and a classical education with the emphasis on greek and latin, stähelin studied medicine in basel, zürich and florence (1944–1950). his first position after graduation was at the institute of microbiology of the university of basel (1951–1954) where he investigated the morphology and sporulation of anthrax bacilli with the help of the then-new phase-contrast microscope. in may 1951, stähelin was the first to observe naked anthrax bacilli protoplasts, called gymnoplasts, which had left behind their empty cell walls. a year later, during his studies of their osmotic behavior, he discovered and described the occasional fusion of naked protoplasts. this seminal paper in german immediately caught the attention of the bacterial geneticist joshua lederberg, who personally requested a copy.