One of the most famous personalities who bore the last name Weismann was Friedrich Leopold August Weismann. He was born in the city of Frankfurt am Main on January 17, 1834. He was a biologist from Germany. According to Ernst Mayr, he was the second most famous proponent of the theory of evolution in the 19th century, after Charles Darwin.

He was an advocate of the theory of germ plasms. The germ plasm theory which was propounded by Weismann states that a multicellular organism consists of germ cells. These germ cells pass on hereditary information. Apart from these germ cells, the multicellular organisms also consist of somatic cells. These somatic cells perform the functions which are performed by the body.

The germ cells are not affected by anything which is learnt by the body or any ability which it acquires during its lifetime. It cannot pass on this information to the next generation .This is known as the Weismann barrier.