 |
| Bubbles: possible precursor of cells |
Human understanding of cells, their purposes and place in Biology has a long incremental historical development. It has taken place over many centuries and been slowly added on to by a number of different researchers and scientists. As contributions were made by so many researchers at different times and through various controversies, it is difficult to track the theory accurately and linearly. Also inseparable from cell theory are the microscopes and related technology like sample preparation which have made cells visible. Most often the advances in cell theory have come from individuals who have concurrently contributed to advancements in microscope technology. Such advances in technology have given those individuals unique perspectives into worlds that were previously unseen by human eyes and from those new unique perspective articulate how the microscopic world works. Although there are a few fundamental principles of cell theory many aspects of the cell have been further elucidated even in the last few decades and some basic tenets of modern cell plasma membrane theory like the sodium potassium pump are still in question. While these current developments are briefly touched on, the main focus of this assignment will be on the fundamental principles of cell theory and its development.
 |
| Onion Cells |
Those fundamental principles are: 1 All living organisms are composed of one or more cells or cell derivatives. 2 Cell is the unit of life and the common structural unit in all living things. 3 All cells arise from other cells.
Although there were many curious people like Hans and Zacharias Jansen and Galileo who tinkered around with lenses, microscopes and theorized about them they were mostly not much more than a curiosity previous to Robert Hooke. In addition to his work refining the microscope Hooke was one of the first to write a complete study of what he saw in Micrographia published 1665 which also gathered interest in studies with microscopes. Hooke was also the first to recognize cells and name them along with a number of other organisms.
Antoni van Leewenhoek around the same time made contributions to both microscopy and understanding of cells. Although van Leewenhoek had little training in the sciences, only spoke Dutch and used only a simple microscope as opposed to the compound microscope used by Hooke, with a skillfully ground lens of magnification of 160 Leeuwenhoek was able to view many human cells like red blood cells and a sperm cell for the first time. Even though these human cells were in view, surprisingly it took another 170 years before the generalization was made that all organisms are made up of the same single celled units.
Along with Hooke two major contributions came almost simultaneously and as breakthroughs seem to often come in counter-opposing pairs by Nehemiah Grew (great name for a biologist BTW) and Marcello Malphigi. Both Grew and Malphigi looked primarily at plants as they were easier to fix and view under a microscope, which shows one of the limiting factors of the technology at the time. Grew used similar words to Hooke in his descriptions but thought the space to be bubbles which had formed by a similar process which seemed more logical in plants than it would have in animals. (The bubble explanation is one that is similar in evolution for how cells have been proposed to have originated.) He believed these bubbles to be interconnected while Malphigi called them sacs and thought they were isolated. Although Malphigi’s view was much later was shown to be more accurate the two views served to strengthen the overall acceptance of cells in the scientific community of the time.
Over the course of the next decades researchers in Biology began to show interest in the existence a fundamental smallest unit of life while simultaneously researchers with microscopes were discovering parts of the cell like the nucleus. An increasing number of microscopists also contributed to observations of cell and nucleuses in other areas for example, Alex Monro saw cells in bones and Caspar Wolff saw them in fat. Robert Brown saw a nucleus in skin cells. Others like Henri Milne-Edwards, Henri Dutrochet, Francois Raspail, Barthelemy Dumortier, Franz Bauer, Jan Purkinje, Von Baer, Wagner may have grasped parts of the the theory but did not completely demonstrate it. Although some of these researchers personally recorded and articulated aspects of cell theory around the same time, the full theory was not fully demonstrated or widely accepted until Theodor Schwann did so in 1837.
 |
| Johannes Muller- Mulled it over, but couldn't get past vitalism |
Muller did make some lasting contributions of his own to the scientific advancement of physiology in his work Elements of Physiology, but he was limited due to his continued belief in vitalism or the idea the living things have a special component that makes them unique and therefore exempt from the laws that govern from non-living things. A belief that had been perpetuated and held back the achievements in Biology.
 |
| Theodor Schwann- Muller's protege who brought Biology out of the darkness of superstition |
Finally the basic unit of Biology and life had been enunciated which put Biology in touch with modern science and paved the way for Pasteur and the golden age of Biology. It had been nearly 200 years since Hooke had first described cells in cork yet it took until this time for humankind to grasp their significance.
Although the theory was initially published and had endless implications there were shortcomings in the paper mistaken descriptions of cell replication when which had to be corrected in later years by Rudolf Virchow.
This was for Science Technology and Society course at Western Governors University. The requirements were to choose a scientific theory and write about its history and its formation.
Requirements:
A. Analyze a scientific theory of your choice by doing the following:
1. Summarize the major tenets of your chosen theory
Discuss how new ideas refined old ideas in the development of your chosen theory.
b. Discuss the role technology or mathematics played in the development of your chosen theory.
c. Discuss how interactions within the scientific community influenced the development of your chosen theory.
d. Discuss the roles that the following epistemological factors played in the development of your chosen theory: empirical standards, logical arguments and skepticism.
3. Compare two major scientific contributions made to the development of your chosen theory.
a. Analyze how the following factors influenced each of the scientific contributions from part A3: prevailing assumptions, personal and societal beliefs, scientific attitudes, talents of individual scientists.
Although I was probably more interested in Antoine Lavoisier's Oxygen theory of combustion I decided to do cell theory because it was more relevant to High School Biology.
References:
1911 Encyclopædia Britannica, Volume 24
Evolution of the Membrane and Bulk Phase Theories
Gilbert N. Ling gilbert.ling.org Skepticism about bulk transport and membrane theory.
The cell theory, past and present : being the inaugural address delivered November 1, 1889, to the Scottish Microscopical Society
Title:A History of Human Anatomy Persaud, T. V. N., Tubbs, R. Shane, Loukas, Marios p 236 microscopy
Harris, Henry. The Birth of the Cell. New Haven, CT: Yale University Press, 1999.
Magner, Lois N. History of Life Sciences, 2nd ed. New York: Marcel Dekker, 1994.
The cell theory, past and present : being the inaugural address ... Turner, Wm. Sir, (William), 1832-1916.
Notes:Intro with things people use that wouldn't exist without cell theory. Include cork and other cell resembling pictures.
Robert Hooke used a compound microscope while another major contributor to cell understanding was Antoni van Leeuwenhoek who used a simple microscope with a skillfully ground lens with a magnification power of 160.
Mathias Schleiden was the first to suggest that all cells have a nucleus although others made similar observations leading up to a full declaration of cell theory. Schleiden primarily worked with plant while the other co-founder of cell theory Theodor Schwann looked mostly at animal cells. They summarized all previous finding in two simple yet infinitely vast reaching premises:
Some might assert that cell theory is well beyond theory at this point since all living things have been found to be composed of cells yet there remains the possibility that we find a new species that doesn’t have cells?
Math was used in calculating the size and number of cells in a given area and technology especially the microscope and slide fixing had to be developed.
