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The cell is the basic building block of all forms of life and is the smallest unit which can be biologically defined as being alive. You can think of cells like bricks which are combined together to build a house of any size or shape. A life form can consist of trillions of cells or it can just exist as a single cell, like an amoeba.
Though the cell might be the smallest building block, it does not mean to say that it cannot be further subdivided. The cell structure consists of several parts, and in eukaryotic cells this includes the cell nucleus. The person who discovered its existence was a botanist known as Robert Brown.
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A Brief Life Sketch of Robert Brown
Robert Brown was an eminent Scottish botanist who lived during the eighteenth and nineteenth centuries. After completing his studies in medicine at the University of Edinburgh in Scotland he joined the army as a surgeon at the young age of 22 years.
Robert Brown lived a life full of enthusiasm and after serving in the army for half a decade, he decided to go to Australia on a survey ship named the Investigator. His purpose was to carry out extensive natural research on the continent's flora.
On his return to Britain he spent several years analyzing the biological specimens he collected from the land down under and started to publish his findings. In 1827 he took charge of the Banksian Botanical Collection at the British Museum.
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Discovery of the Cell Nucleus
The term cell nucleus was used by Robert Brown for the first time in 1831 in a paper to the Linnean Society and it was published in 1833. At the time of publishing he did not realize that cell nucleus was present in cells other than those belonging to plants.
During his stay in Australia Brown studied nearly 1700 plant species and other notable observations include the identification of naked ovule of the gymnospermae.
While he was scrutinizing the epidermis of a collection of orchids with his microscope, Brown found that the cells contained an opaque spot. He used the term areola to describe them. They had been seen by other scientists previously who most likely regarded them as insignificant.
But Brown was not to ignore this specific observation and he further noted that the spot was not limited to the epidermis as it could also be observed during the early stage of pollen formation. He sensed that this spot was a key component of cells and called them "nucleus" - a term which is still being used today.
Another point worth mentioning at this stage is that though he is universally acknowledged as being the discoverer of the cell nucleus, Brown also gave credit to Franz Bauer who was a contemporary botanist and had made similar observations.
Apart from discovering the cell nucleus, Brown's other important contribution to science was the discovery of the phenomenon known as "Brownian motion." Looking at pollen grains suspended in water he could see that they were jiggling about, but he couldn't understand why. It was Einstein in 1905 who provided an explanation, namely that the pollen was moving because it was being hit by invisible water molecules.