Anton van Leeuwenhoek
Antony van Leeuwenhoek was an unlikely scientist. A tradesman of Delft, Holland, he came from a family of tradesmen, had no fortune, received no higher education or university degrees, and knew no languages other than his native Dutch. This would have been enough to exclude him from the scientific community of his time completely. Yet with skill, diligence, an endless curiosity, and an open mind free of the scientific dogma of his day, Leeuwenhoek succeeded in making some of the most important discoveries in the history of biology.
Anton van Leeuwenhoek started as an apprentice in a dry goods store where magnifying glasses were used to count the threads in cloth. He was inspired by the glasses used by drapers to inspect the quality of cloth. He taught himself new methods for grinding and polishing tiny lenses of great curvature which gave magnifications up to 270x diameters, the finest known at that time. These lenses led to the building of Anton Van Leeuwenhoek’s microscopes considered the first practical microscopes, and the biological discoveries for which he is famous.
It was he who discovered free-living and parasitic microscopic protists in 1674 followed by bacteria in 1676, sperm cells and blood cells in 1677 and muscular fibers in 1682. Anton discovered many more in the following years and his research was widely circulated which opened up an entire world of microscopic life to the awareness of scientists.
Robert Brown
During a visit to London in 1798 Robert Brown was introduced to Sir Joseph Banks. This led, two years later, to his being recommended by Banks for the post of naturalist on the Investigator in an expedition to survey the coast of New Holland (Australia).
The Essay on Cells Cell People Leeuwenhoek
History of the Cell Theory Ryan Strehlein Cells, the make-up of all living things. Some cell are complete organisms, such as unicellular bacteria and protozoa. Other types of cells a recalled multicellular, such as nerve cells and muscle cells. Within the cell is genetic material, Deoxyribonucleic Acid (DNA) containing coded instructions for the behavior and reproduction of the cell. The cell was ...
Brown accepted the appointment and the Investigator set sail for the Cape of Good Hope and Australia in 1801.
During his five years with the expedition Brown collected 4000 plant specimens, and on his return to England spent another five years classifying these. By 1810 he had described 2200 species, over 1700 of which were new (including 140 new genera).
He intended to produce an extensive treatise on Australian plants but the poor sales of the first volume, which appeared in 1810, led him to discontinue publication of the remainder.
In the course of his painstaking work Brown became very familiar with plant morphology, which led him to make many important observations. He found that in conifers and related plants the ovary around the ovule is missing, thus establishing the basic difference between these plants and flowering plants or between the gymnosperms and the angiosperms, as the two groups of seed-bearing plants were later named. He also observed and named the nucleus, recognizing it as an essential part of living cells.
In 1827, while examining a suspension of pollen grains in water, under a microscope, Brown observed that the grains were in continuous erratic motion. Initially he believed that this movement was caused by some life force in the pollen, but when he extended his observations to inanimate particles suspended in water he found the same effect. This phenomenon was named Brownian motion and remained unexplained until the kinetic theory was developed.
Bibliography
Robert Brown
http://www.answers.com/topic/robert-brown. (n.d.).
Retrieved September 12th, 2010,
http://www.brianjford.com/wbbrowna.htm. (n.d.).
Retrieved Septemeber 12th, 2010,
Anton van Leeuwenhoek
http://inventors.about.com/library/inventors/blleeuwenhoek.htm. (n.d.).
Retrieved September 12th, 2010
http://www.ucmp.berkeley.edu/history/leeuwenhoek.html. (n.d.).
Retrieved September 12th, 2010
