Work

From the beginning an organism evolves from one cell, which divides and becomes new cells that in turn divide. They form an embryo—a group of cells with different parts, out of which the brain, mouth, skeleton, intestine and other parts are formed. Around 1920 Hans Spemann succeeded in using fine pipettes or loops of children’s hair to move around different parts of a frog embryo. He demonstrated that certain groups of cells adapt themselves to their surroundings while others, such as the bilaterian mouth, have an organizing effect on their surroundings.