Nägeli or Naegeli, Karl Wilhelm von (both: kärl vĭlˈhĕlm fən nāˈgəlē) [key], 1817–91, Swiss botanist. He was professor at the Univ. of Munich from 1858 and was noted especially for his work on plant cytology and development. He made studies of the process of division in pollen grains and in unicellular algae, and he determined the function of many plant parts, such as the antheridia and spermatozoids of ferns. In his studies of cells he made a distinction between the nuclear material and a mucous layer of living matter (protoplasm).