Hammerling's experiment with the single celled green algae, Acetabularia,
showed that the nucleus of a cell contains the genetic information that
directs cellular development.
A. mediterranea has a smooth, disc shaped cap, while A. crenulata
has a branched, flower-like cap. Each Acetabularia cell is composed
of three segments: the "foot" or base which contains the nucleus,
the "stalk," and the "cap."
In his experiments, Hammerling grafted the stalk of one species of Acetabularia
onto the foot of another species. In all cases, the cap that eventually
developed on the grafted cell matched the species of the foot rather than
that of the stalk. In this example, the cap that is allowed to grow on the
grafted stalk looks like the base species one... A. mediterranea.
This experiment shows that the base is responsible for the type of cap
that grows. The nucleus that contains genetic information
is in the base, so the nucleus directs cellular development.
Hammerling's Acetabularia From: Peters, Pamela. "Biotechnology:
A Guide to Genetic Engineering." Dubuque, IA: William C. Brown Publishers,