The subsequent division of the cytoplasm results in uninucleate masses of protoplasm. The dense protoplasm of meristematic cells contains very few vacuoles. The cells are small, with no or small vacuoles and protoplasm fills the cell completely. They consist of translucent protoplasm with fine interlacing filaments and minute granules are sometimes present. Phytoplankton use photosynthesis to convert inorganic carbon into protoplasm. Like the nucleus, whether to include the vacuole in the protoplasm concept is controversial. Myxomycete plasmodia are multinucleate masses of protoplasm that move by cytoplasmic streaming. Once the protoplasm divides, it differentiates into reproductive cells. This tissue consists of thick-walled, dead cells and protoplasm is negligible. The cell was a container for protoplasm, the fundamental and universal material substance of life. The diagnostic stage is the immature oocyst that contains a spherical mass of protoplasm. Such criticisms stimulated continued studies on protoplasm as the principal agent determining cell permeability properties. Huxley's principal contribution was to establish protoplasm as incompatible with a vitalistic theory of life. His body changed into an unstable protoplasm. The protoplasm became an "epistemic thing".