2. The cell is structural & functional unit of all living things.
3. All cells come from pre-existing cells by division. (Spontaneous Generation does not
occur).
4. Cells contains hereditary information which is passed from cell to cell during cell
division.
5. All cells are basically the same in chemical composition.
6. All energy flow of life occurs within cells ie all metabolism in an organism occur
within cells
The organismal Theory:
The organismal theory states that an organism is the basic unit of life. It was put forward in the
early part of the 19th century as a counter argument to the cell theory. In plants, the organismal
theory refers to the idea that during plant growth and evolution, the original cell expanded to give
rise to the whole organism. This is opposed to the cell theory that states that a cell multiplies into
many cells with the original cell being equivalent to many. According to the organismal theory,
the original cell is equivalent to the entire organism with the protoplasm just being sub-divided by
the cell walls. The cell walls according to this theory are incomplete portions because the
protoplasm of adjacent cells are connected by plasmodesmata.
NB: Organismal theory holds the view that the organism rather than the cell is the basic unit of
life. This observation is based on the following:
Some organisms such as fungi (the coenocytic fungi) are non-cellular and are unable to
divide into cellular compartments.
Plant cells have cytoplasmic bridges between each other called plasmodesmata.
some of the cells lack some basic components such as red blood cells and nucleus.
Cytoplasm in unicellular organisms does not undergo subdivision into cells.
If any cell is removed from the multicellular organisms, it would require complete life
support to be alive.
There are cytoplasmic connections between cells in plants (plasmodesmata)
Extensive communication among cells and constant adjustment of cellular activities is
required to keep organisms alive.
Proponents of the organismal theory and their reasoning:
Organismal theory was explained and supported by several scientists such as Reichert (1939), a
morphologist who stated that an organism has a structured plan and cannot be looked at in terms
of individual cells as advocated by the cell theory; Strasberger a cytologist argues that cells in an
organism are connected by cytoplasmic bridges, and Sherrington and Pavlov (neurophysiologists)
says cells communicate with each other and co-ordinate with their actions and according to these
scientists, organisms should not be looked at in terms of individual cells.
5
3. All cells come from pre-existing cells by division. (Spontaneous Generation does not
occur).
4. Cells contains hereditary information which is passed from cell to cell during cell
division.
5. All cells are basically the same in chemical composition.
6. All energy flow of life occurs within cells ie all metabolism in an organism occur
within cells
The organismal Theory:
The organismal theory states that an organism is the basic unit of life. It was put forward in the
early part of the 19th century as a counter argument to the cell theory. In plants, the organismal
theory refers to the idea that during plant growth and evolution, the original cell expanded to give
rise to the whole organism. This is opposed to the cell theory that states that a cell multiplies into
many cells with the original cell being equivalent to many. According to the organismal theory,
the original cell is equivalent to the entire organism with the protoplasm just being sub-divided by
the cell walls. The cell walls according to this theory are incomplete portions because the
protoplasm of adjacent cells are connected by plasmodesmata.
NB: Organismal theory holds the view that the organism rather than the cell is the basic unit of
life. This observation is based on the following:
Some organisms such as fungi (the coenocytic fungi) are non-cellular and are unable to
divide into cellular compartments.
Plant cells have cytoplasmic bridges between each other called plasmodesmata.
some of the cells lack some basic components such as red blood cells and nucleus.
Cytoplasm in unicellular organisms does not undergo subdivision into cells.
If any cell is removed from the multicellular organisms, it would require complete life
support to be alive.
There are cytoplasmic connections between cells in plants (plasmodesmata)
Extensive communication among cells and constant adjustment of cellular activities is
required to keep organisms alive.
Proponents of the organismal theory and their reasoning:
Organismal theory was explained and supported by several scientists such as Reichert (1939), a
morphologist who stated that an organism has a structured plan and cannot be looked at in terms
of individual cells as advocated by the cell theory; Strasberger a cytologist argues that cells in an
organism are connected by cytoplasmic bridges, and Sherrington and Pavlov (neurophysiologists)
says cells communicate with each other and co-ordinate with their actions and according to these
scientists, organisms should not be looked at in terms of individual cells.
5
