This leads to Robert Hooke discovering cells.
Anton van Leeuwenhoek uses a simple microscope with only one lens to look at blood, insects and many other objects. He was first to describe cells and bacteria, seen through his very small microscopes with, for his time, extremely good lenses.
He does this in the form of algae and protists and sperm.
He does this by analyzing a sample of saliva and plaque he took from his, his wife's, daughter's, and another man's mouth.
He stated that the different parts of plants are all made up of cells or derivatives of cells.