Comparing organs in marine animals
Hertwig’s early work with his elder brother Oscar examined medusan nervous systems and sensory organs, as well as the anatomy of sea anemones. Their studies of medusae in 1878 and sea anemones in 1879 used comparisons of organs to investigate evolutionary relationships.
References: [1]
Fertilization and unicellular organisms
The brothers altered external conditions to investigate fertilization and division in sea urchin eggs. Richard later concentrated on organisms then classified as protozoa, studying conjugation in ciliates and nuclear division and fertilization in Actinosphaerium. These relatively simple cellular systems allowed reproductive processes and nuclear changes to be observed experimentally.
References: [1]
Research and teaching in Munich
In 1885 Hertwig moved to Munich, where he directed the zoological institute and zoological collections and worked for about forty years. Alongside university teaching and support for students’ independent research, he took an interest in biology teaching in secondary schools.
References: [1]
A repeatedly revised zoology textbook
His Lehrbuch der Zoologie first appeared in 1891–1892 and was repeatedly revised and translated. The textbook and his teaching brought extensive knowledge of animal groups, comparative morphology and developing experimental questions into a common zoological framework.
References: [1]