By early 1800s, the accepted idea was that plants and animals were composed of globules called cells. Robert Brown enhanced this idea by describing the nuclei in cells of orchid plants.
In 1838, a German botanist, Matthias Schleiden suggested that cells were the basic structural unit of all plant matter. German zoologist, Theodor Schwann proposed that animals were made up of cells. The two biologists came to recognise that both plant and animal tissues have a cellular organization.
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