why was the invention of the microscope important
The microscope is a device used to make very tiny (microscopic) objects visible to the human eye through magnification. The very first microscopes had only one lens, and were referred to as simple microscopes. Compound microscopes have at least two lenses and were invented in the 1590s. The first microscopes relied on light to see the sample being viewed and were called optical microscopes. As science advanced new methods were used and today there are a variety of different microscopes including the electron microscope, the ultramicroscope, and scanning probe microscopes.
In 1824 Frenchman Henri Milne-Edwards suggested that the basic structure of all animal tissues was an array of globules, though his insistence on uniform size for these globules puts into question the accuracy of his observations. Henri Dutrochet (1776 1847) made the connection between plant cells and animal cells explicit, and he proposed that the cell was not just a structural but also a physiological unit: It is clear that it constitutes the basic unit of the organized state; indeed, everything is ultimately derived from the cell (Harris 1999, p. 29). Dutrochet proposed that new cells arise from within old ones, a view that was echoed by his contemporary Fran ois Raspail (1794 1878).
Raspail was the first to state one of the two major tenets of cell theory: Omnis cellula e cellula, which means Every cell is derived from another cell. However, despite this ringing and famous phrase, his proposed mechanism of cell generation was incorrect. Raspail was also the founder of cell biochemistry, making experiments on the chemical composition of the cell and their response to changing chemical environments. In 1832 Barthelemy Dumortier (1797 1878) of France described binary fission (cell division) in plants. He observed the formation of a mid-line partition between the original cell and the new cell, which, Dumortier noted, seems to us to provide a perfectly clear explanation of the origin and development of cells, which has hitherto remained unexplained (Harris 1999, p. 66) These observations led him to reject the idea that new cells arise from within old ones, or that they form spontaneously from noncellular material. The discovery of cell division is usually attributed to Hugo von Mohl (1805 1872), but Dumortier proceeded him in this regard. Von Mohl did coin the word protoplasm for the material contained in the cell.
The first unequivocal description of the cell was made by a Czech, Franz Bauer, in 1802 and was given its name in 1831 by Robert Brown (1773 1858) of Scotland, who is best remembered for discovering the random Brownian motion of molecules. The first accurate description of the nucleolus was made in 1835. Schleiden and Schwann, who are usually given credit for elucidating the cell theory, made their marks in 1838 and 1839. In 1838 Matthais Schleiden (1804 1881) proposed that every structural element of plants is composed of cells or the products of cells. However, Schleiden insisted on priority for several ideas that were not his and clung to the idea that cells arise by a crystallization-like process either within other cells or from outside, which Dumortier had dispensed with some years earlier. (In Schleiden s defense, it should be remembered that drawing incorrect conclusions from limited observations is a risk inherent in science, especially when working on the frontier of a new field. ) In 1839 a fellow German, Theodor Schwann (1810 1882), proposed that in animals too every structural element is composed of cells or cell products.
Schwann s contribution might be regarded as the more groundbreaking, since the understanding of animal structure lagged behind that of plants. In addition, Schwann made the explicit claim that the fundamental laws governing cells were identical between plants and animals: A common principle underlies the development of all the individual elementary subunits of all organisms (Harris 1999, p. 102). A special word should be said here about the Czech Jan Purky e (1787 1869), or Purkinje, as his name is usually given. Purkinje was the premiere cytologist of his day, and one of the most influential formulators of the cell theory. He gave his name to structures throughout the body, including the Purkinje cells of the cerebellum. Purkinje, in fact, deserves much of the credit that usually goes to Schwann, for in 1837 he proposed not only that animals were composed principally of cells and cell products (though he left room for fibers) but also that the basic cellular tissue is again clearly analogous to that of plants (Harris 1999, p. 92). Unfortunately, Schwann did not credit Purkinje in his influential publication.
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