Cell division is the process by which an organism grows or replaces damaged tissue. The growth of a fertilized embryo is accomplished through the division and differentiation of cells, and while some cells, such as skin cells, divide almost continuously after birth, other highly specialized cells, such as some neurons, do not and cannot be replaced after disease or injury. The two forms of cell division, mitosis and meiosis, are the biological mechanism by which the principles of heredity and evolutionary theory are realized.

German botanist Wilhelm Hofmeister (1824-1877) first examined the process of cell division in 1847 and showed that the nucleus did not truly disappear. He appeared to have been very close to discovering chromosomes, but that honor was left to Walther Flemming some 30 years later.

Prior to Flemming's work, little headway had been made in the field of cytology since Hofmeister's discovery, due in...