The study of cells often brings a great lot of fascination with it. Part of this fascination, for many, is due in part to the fact that such minuscule objects can harbor so much information, and be so complex, all while being absolutely invisible to the naked eye. When we study cells in the laboratory, we use what is known as a microscope, which allows an image to be magnified many times its original size (Karp 2013).
Microscopes were created several hundred years ago. And quite fittingly, the cell was discovered by a microscopist, Robert Hooke, who at merely age 27 had already received some scientific distinction, by being awarded the position of curator of the Royal Society of London, England’s foremost scientific academy. However, Hooke’s story is rather humorous, as one of the questions Hooke attempted to answer was why cork stoppers (such as those of wine bottles) were so good at holding air in. When Hooke sliced a thin layer of the a cork off and examined it under a microscope, he noted porous holes, which he called cells, because of their resemblance to the cells in which monks at a monastery resided. We now know that Hooke was actually looking at the empty cell walls of dead plant tissue, particularly that of the bark of trees, from which cork is derived. These walls had been produced originally by the living cells that they once encompassed (Karp 2013).
Another scientist, Dutchman Anton van Leeuwenhoek was at this time producing microscopes, by grinding lenses. He became the first person to look at a drop of pond water under the microscope, and observed the many living entities inside of it. He further was able to describe forms of bacteria that he witnessed under the microscope, from scrapings of his teeth and water in which pepper had been soaked. All the while, Leeuwenhoek was writing letters to the Royal Society about his findings, where Hooke was employed. Hooke was sent to confirm the observations reported by Leeuwenhoek after they were met with immense skepticism, catapulting Leeuwenhoek to scientific fame (Karp 2013).
Despite this, it was much later in time, in the 1830s, when the true importance of cells was realized. Matthias Schleiden, a German lawyer turned botanist, came to the conclusion in 1838 that plants were composed of cells, despite differences in the structure of various tissues. He also concluded that the plant embryo arose from a single cell. Later on, the beginnings of the cell theory were developed by a German zoologist who was a colleague of Schleiden’s, Theodor Schwann. He proposed that (1) all organisms are made up of one or more cells and that (2) the cell is the structural unit of life. Though these proposals were remarkable, others by the two scientists were less so. And then later, in 1855, a German pathologist, Rudolf Virchow, provided another remarkable proposal, which in addition to the two listed above, made a good case for the third tenet of the cell theory: that (3) only through division of preexisting cells can new cells arise (Karp 2013).
In short, if you feel that it does not behoove you to remember any of the history in this post, do remember the three tenets of the cell theory, as originally paraphrased above, from Gerald Karp’s text:
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