Cell Theory

Aristotle's Theory of Spontaneous Generation

400

Resource4th century BC: Aristotle thought that the properties of living organisms were due to the mixture of principles and elements in each part of the body, plus an animating force he called "pneuma" or the Latin word for soul. He states several times that animals of some kinds arise directly from elements and the pneuma of the material.

Recipe of Mice Reported

Nov 10, 1500

ReferenceIn the 1500's Spontaneous Generation of mice was reported by Jan Baptista van Helmont(1579-1644), a physician and alchemist. The recipe stated that mice arose when a flask of wheat and old rags was incubated in a warm dark closet for 21 days.

First Compound Microscope Invented

Nov 10, 1595

ReferenceIn 1595 Zacharias Jansen and Hans produce the first compound microscope by combining two convex lenses within a tube.

Cells First Observed

Nov 10, 1665

ReferenceIn 1665, Robert Hooke, an English scientist discovered a structure in a thin slice of cork using a primitive compound microscope.

First Living Cells Seen

Nov 10, 1670

ReferenceAnton van Leeuwenhoek, a Dutch Biologist looks at pond water through a microscope and discovers living cells.

Miniature Animals

Nov 10, 1683

ReferenceLeeunenhoek made several more discoveries on a microscopic level, eventually publishing a letter to Royal Society in whick he included detailed drawings of what he saw, which he called "animolecules" among these were the first Protozoa and Bacteria discovered.

Cells Consisted and Formed From Other Cells

Nov 10, 1805

ReferenceLorenz Oken made a further advance in the application of the principle, in a book on generation, in which he maintained that "all organic beings originate from and and consist of vescicles and cells."

Cell Theory

Nov 10, 1839

ReferenceTheodor Schwann, a German Botanist reacked the conclusion that not only plants, but animal tissue as well, is composed of cells. This ended debates that plants and animals were fundamentally different in structure. He also pulled together and organized previous statementson cells into one theory: Cells are organisms and all organisms consist of one or more cells. The cell is the basic unit of structure for all organisms.

Where Life Comes From

Nov 10, 1840

ReferenceAlbrecht von Roelliker discovers that sperm and egg are also cells.

Basic Unit of Life

Nov 10, 1845

ReferenceCarl Heinrich Braun reworks the cell theory calling cells the basic unit of life.

Third Part of Cell Theory Added

Nov 10, 1855

ReferenceRudolf Virchow, a German Physiologist added the third part to cell theory:all cells develop from existing cells. He also was the first to propose that diseased cells come from healthy cells.

Disproving Spontaneous Generation

Nov 10, 1859

ReferenceLouis Pasteur, a french scientist who worked with yeast cells, set out to dissprove spontaneous generation with an experiment. He demonstrated that micro-organisms were not able to rise from completely non-living matter. This firmly established the Cell Theory beyond doubt and solified the scientific method.

The Center of the Cell Seen

Nov 10, 1883

ReferenceRobert Hooke, and English botanist discovered the nucleus in plant cells.

Basic Building Blocks

Nov 10, 1883

Reference(2)Refernce(1)Mathias Jakob Schleiden a German botanist, proposes that all plant tissues are composed of cells, and that cells are the basic building blocks of all plants. This statement was the first generalized statement about cells and is the first part to the Cell Theory.