–1897) was a German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 zoologist and evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

ary morphologist

Morphology (biology)

In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

.

He studied at the University of Jena under Ernst Haeckel

Ernst Haeckel

The "European War" became known as "The Great War", and it was not until 1920, in the book "The First World War 1914-1918" by Charles à Court Repington, that the term "First World War" was used as the official name for the conflict.-Research:...

 obtaining his doctorate for studies of embryo

Embryo

An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

 cleavage in Hydra

Hydra (genus)

Hydra is a genus of simple fresh-water animal possessing radial symmetry. Hydras are predatory animals belonging to the phylum Cnidaria and the class Hydrozoa. They can be found in most unpolluted fresh-water ponds, lakes, and streams in the temperate and tropical regions and can be found by...

.His later work Hydra - Eine anatomisch-entwicklungsgeschichtliche untersuchung, in English An anatomical-evolutionary investigation of Hydra (Leipzig, Wilhelm Engelmann, 1872) is a classic still quoted monograph which has implications for evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 theory.

Kleinenberg was a close friend of Anton Dohrn

Anton Dohrn

Felix Anton Dohrn was a prominent German Darwinist and the founder and first director of the Stazione Zoologica, Naples, Italy.-Family history:...

 helping him to found the marine station at Messina where he was professor.He worked with Ilya Ilyich Mechnikov

Ilya Ilyich Mechnikov

Ilya Ilyich Mechnikov was a Russian biologist, zoologist and protozoologist, best remembered for his pioneering research into the immune system. Mechnikov received the Nobel Prize in Medicine in 1908, shared with Paul Ehrlich, for his work on phagocytosis...

 and Rudolf Ludwig Karl Virchow on their visits to Messina.