Nature Bulletin No. 115 May 10, 1947
Forest Preserve District of Cook County
William N. Erickson, President
Roberts Mann, Supt. of Conservation
Plants and animals are made up of livlng substances. About 200 years
ago it was discovered that living substances are divided into
microscopic bits called cells. Bacteria and many kinds of primitive
microscopic plants and animals were found to consist of one single cell
each. A piece of skin was seen to be built of several layers of cells, each
layer fitted together, like bricks in a wall Sometimes the cells are long
and threadlike, as in muscles and nerves; sometimes they are irregular
blocks; sometimes they are long and branching.
In 1865 an Austrian monk, Gregor Mendel, reported the results of many
years of experiments wherein he found that certain colors and shapes of
peas were inherited as if definite units of heredity were transmitted
through the female egg cells and the male pollen cells of the flowers.
By crossing a wrinkled green pea with a smooth yellow pea he obtained
several combinations including two new pure strains: a smooth green
pea and a wrinkled yellow pea. Unfortunately, Mendel's report was lost
to science until 1300. Then, very quickly, hundreds of scientific
workers became interested and soon it was shown that the hereditary
units, called genes, were transmitted as unchanged units from
generation to generation, explaining the transmission of hereditary
qualities of plants and animals from one generation to the next.
Eventually it was shown that these genes were located in tiny rod-
shaped bodies, called chromosomes, inside the nucleus of each cell; and
that a row of genes, arranged like a string of beads, ran lengthwise in
each chromosome From studies of mice, fruit flies, corn and other
animals and plants, it appeared that each cell contained hundreds,
perhaps thousands, of different genes. Geneticists, the people
specializing on studies of heredity, now believe that genes are the most
fundamental living unit and do all the important work in living
The cell is the house that gene built.
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Update: June 2012