A worksheet function that is called by Excel can call back into Excel using the C API. An XLL command that is called by Excel can call the C API. DLL and XLL functions and commands that are called by VBA when VBA has itself been called by Excel can call the C API.
Cell Theory. The discovery of the cell was made possible by the invention of the microscope, which was made possible by improved lens-grinding techniques.Antoni van Leeuwenhoek (1632-1723), a Dutch tradesman, learned to grind lenses and assemble them into simple microscopes.nspired by Hooke's work, Leeuwenhoek began making microscopic examinations of his own. In 1678, he reported to the Royal Society that he had discovered little animals -- bacteria and protozoa -- in various samples. The society asked Hooke to confirm Leeuwenhoek's findings, and he did.
Hookeâs Discovery of Plant Cells. Hooke looked at the bark of a cork tree and observed its microscopic structure. In doing so, he discovered and named the cell â the building block of life. He thought the objects he had discovered looked like the individual rooms in a monastery, which were known as cells.Hooke did not discover the true biological function of cells. Plant cells, discovered, named and drawn by Robert Hooke.e thought the objects he had discovered looked like the individual rooms in a monastery, which were known as cells. Hooke did not discover the true biological function of cells. Plant cells, discovered, named and drawn by Robert Hooke.