Schwann, Theodor (1810–1882)
German naturalist who established that cells
were the fundamental units of life (1839), thus laying the foundations of
modern histology, and played a part in
disproving the idea of spontaneous generation.
Schwann showed that the putrefaction
of meat required the presence of microscopic organisms, and that if these
were rigorously excluded the meat would remain fresh for long periods of
time. In 1836 he became the first person to prepare an enzyme
from animal tissue when he isolated and named pepsin.