The Molecular Basis of Inheritance The invention of the
microscope made it possible to observe the structural process of
cell division. A fundamental observation was made; growth
follows a strict pattern in which one cell can divide, giving
rise to two cells. It became clear that during cell division a
set of structures, named chromosomes, were assembled.
Chromosomes differed in their physical appearance and always
were present in pairs. During cell division, each chromosome was
first duplicated and, as the orginal cell divided in two, each
"daughter" cell was provided with a complete set of chromosomes
present in the "parent" cell. A powerful circumstancial case was
developed that the chromosomes contained the genetic material
and provided the structural basis for growth as the genetic
information was transferred from one cell to its offspring
during cell division. From careful studies of fertilization
using isolated egg and sperm it was established that the female
and male partners each contributed one of t