Aulonia hexagona–studied by Ernst Haeckel, with microscopes from the 18th century.
Using handcrafted microscopes, Antonie van Leeuwenhoek was the first to observe and describe microorganisms, which he called animacules. He was the first microbiologist. His skills as a lens manufacturer allowed him to observe a world that no one imagined possible. This happened during the 1670’s. His findings were not met with enthusiasm by his peers:
“Despite the initial success of Van Leeuwenhoek’s relationship with the Royal Society, this relationship was soon severely strained. In 1676, his credibility was questioned when he sent the Royal Society a copy of his first observations of microscopic single-celled organisms. Previously, the existence of single-celled organisms was entirely unknown. Thus, even with his established reputation with the Royal Society as a reliable observer, his observations of microscopic life were initially met with both skepticism and open ridicule. Eventually, in the face of Van Leeuwenhoek’s insistence, the Royal Society arranged for Alexander Petrie, minister to the English Reformed Church in Delft, Benedict Haan, at that time Lutheran minister at Delft, and Henrik Cordes, then Lutheran minister at the Hague, accompanied by Sir Robert Gordon and four others to determine whether it was in fact Van Leeuwenhoek’s ability to observe and reason clearly, or perhaps the Royal Society’s theories of life itself that might require reform. Finally in 1677  Van Leeuwenhoek’s observations were fully vindicated by the Royal Society.” — Via
Almost 350 years later we have been able to observe chemical reactions. We can see atoms with very powerful microscopes. But, does this mean that everyone has seen a cell? Like Leeuwenhoek before us; Science Club and Biology students were able to observe specimens using self-made microscopes at more or less the same magnification: between 50 and 200 times the original size. For this we used: 1) bobby pins, 2) lenses (taken from key chain laser pointers), 3) and a mobile device camera:
[H/T] for the photos to: Adriana, Gerardo & Gustavo (Science Club); Ana & Lorenzo (10-5); Sofía, Diego, Bianca, Christian & Andrea (10-4).