Antonie Philips van Leeuwenhoek (October 24, 1632-August 26, 1723) was a Dutch tradesman and scientist. He is known as "the Father of Microbiology", and considered to be the first microbiologist. He is best known for his work on the improvement of the microscope and for his contributions towards the establishment of microbiology. Using his handcrafted microscopes, he was the first to observe and describe single-celled organisms, which he originally referred to as animalcules, and which we now refer to as micro-organisms. Van Leeuwenhoek's main discoveries are: the infusoria (protists in modern zoological classification, in 1674) the bacteria, (large Selenomonads from the human mouth in 1676), the vacuole of the cell, the spermatozoa (1677) and the banded pattern of muscular fibers (1682). Van Leeuwenhoek ground more than 500 optical lenses and created at least 25 microscopes, of differing types, of which nine survive and are capable of magnification up to 275 times.