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.
The word cell was first used by English scientist Robert Hooke in 1665 to describe the cell walls visible in cork when seen through a microscope. In 1838 the German botanist Mâ¦atthias Schleiden concluded that all plant tissues were made of cells. In 1839 the zoologist Theodor Schwann reached the same conclusion about animal tissues. By 1885 the German physiologist concluded that cells only originated by the division of a preexisting cell.