Born-24 October 1632 AD and died-26 August 1723 AD. He is a native of the Netherlands and a Dutch scientist. He is called father of microbiology. He invented the simple microscope. First described unicellular organisms and named them animalcules. He first observed protozoa, bacteria, yeast, red blood cells, sperm, nerve cells, muscle tissue, etc. Describe the circulation of blood inside the capillaries. Describe the life cycle of insects. His book is – On the Circulation of the Blood, Latin Text of His 65th Letter to the Royal Society, Facsimile.