What are motor skills? You might hear about the development of fine and gross motor skills in the pediatricianâs office, parenting magazines or a baby development book. What exactly are they? This is actually a pretty complicated question.
The cell was first discovered by Robert Hooke in 1665 using a microscope. The first cell theory is credited to the work of Theodor Schwann and Matthias Jakob Schleiden in the 1830s. In this theory the internal contents of cells were called protoplasm and described as a jelly-like substance, sometimes called living jelly.
*Hans and Zacharias Janssen had to first develop the microscope before cells could be discovered. Robert Hooke then discovered empty, dead cork cells in tree bark. Anton van Leeuwenhoek discovered the existence of living cells and is sometimes given credit for the microscope. 5. List the three parts of the cell theory.