In a previous blog, I described the 1873 discovery by Camillo Golgi of a method to visualize neurons and his decades-long debate with co-Nobelist Santiago Ramón y Cajal, which led to our current understanding of neuronal function. All of this work was built in turn upon 'cell theory,' the notion that individual cells represent the basic building blocks of all living things. This is, in a sense, a prequel describing how the German botanist Matthias Jakob Schleiden (1804-1881), troubled by periods of melancholy and a number of challenging personality qualities, came to propose this revolutionary way of understanding the role of cells. His story is also a continuance of earlier posts on figures in science, the arts, and politics who have made remarkable contributions in the course of very troubled lives.
The son of a municipal physician in Hamburg, Schleiden obtained a law degree from the University of Heidelberg in 1827 and returned to practice in his hometown. It turned out to be very unsuccessful; he became despondent and ultimately shot himself. Happily, he survived, though marked for life with a conspicuous scar on his forehead, and wisely realized that a change in profession was in order. He began to study medicine and natural science in Göttingen in 1832, as well as botany in Berlin in 1835. He built on the work of the Scottish botanist Robert Brown (as in the ‘Brownian movement’), who had described the nuclei in plant cells. Schleiden came to believe that nuclei were the key component in the embryonic development of cells. Though he erred in his description of how cells are formed, he was prescient in believing that they represent the basic units of plant life. As such, he believed that each cell lives a double life: one based on its own development and another in which it participates as a part of life processes in a plant. He also asserted that any given plant was ultimately derived from a single embryonic cell.
In October 1838, Schleiden had dinner with his friend Theodor Schwann (1810-1882), a young physician and physiologist at the University of Berlin, who at the time had been studying and disproving the notion of spontaneous generation; in his remarkable career, he also described the cells which surround peripheral nerves (‘Schwann cells’), discovered the digestive enzyme pepsin, and also coined the term ‘metabolism.’ Currently, he was looking for a common theme that might explain the developmental relationship of various animal tissues. In this work he had been hampered by the greater difficulty in visualizing animal cells, which lack the more obvious cell walls of plants.
During the dinner, Schleiden described his notion that all plants were comprised of nucleated cells; Schwann suddenly realized that this sounded like what he had been seeing in frog larvae. Afterward, they went to his laboratory, where his microscopic views of animal tissue did indeed seem to confirm Schleiden’s observations in plants. Schwann elaborated on this commonality and, perhaps with more clarity and detail, proposed in 1839 that all living matter was comprised of cells, which are the basic building blocks of life.
In 1855, the German pathologist Rudolf Virchow (1821-1902) added an additional stipulation to what Schwann had entitled cell theory, that cells are created solely from preexisting cells (‘Omanis cellular e cellular’). In 1863, he phrased his overall conception this way: ‘The body is a state in which every cell is a citizen.’ In passing, it should be mentioned that Virchow, like Golgi, led a life of both active scientific research and politics. He had participated in the revolution of 1848 and was a leader of the Progressive Party in the Diet, or Parliament, of Prussia and an enemy of Otto von Bismarck. On one notable occasion in 1865, Bismarck, who was inclined toward 'blood and iron' as a method of conflict resolution, challenged him to a duel; fortunately for the history of science, Virchow demurred.
In modern times, cell theory has been expanded to recognize that DNA is responsible for passing information across generations of cells and that an exception has to be made for viruses, which are not necessarily cells but hold genetic material and can generate new viruses inside of host cells. Nonetheless, the basic proposition that organisms are comprised of cells was in place by the 1860s.
One challenge facing histologists from that point on, however, was that what little they could see of cells in the brain made them look very different from those in other tissues; the nerve cells and their processes were so densely packed that it was hard to separate them visually. This was the situation facing Camillo Golgi when he began his landmark studies in the 1870s, followed by the improvements in his methods by Santiago Ramón y Cajal and the ultimate recognition of neurons as the basic anatomical and functional units of the nervous system.
As for Schleiden: A few weeks after his eventful dinner with Schwann, he had an emotional crisis related to both an unhappy romance and what he described as spiritual emptiness. After another suicide attempt and spending nine months in a small mountain town under the guidance of a pastor, he felt that he had healed and returned to work at a new post at the University of Jena. Some of his theories about the formation of cells and embryogenesis, however, had attracted vociferous criticism, and he became discouraged. (In retrospect, the vigor with which he was attacked likely was a consequence of the harsh and personal quality of his criticisms of others.) After publishing his last purely botanical paper on the reproduction of lichens in 1844, he began to write more broadly about anthropology. In 1862, he was appointed an Imperial Russian State Counselor and taught anthropology at the University of Dorpat until he ran afoul of religious authorities for his outspoken views. He returned to Germany in 1864.
In Dresden and a series of other cities, he set to work as an independent scholar on monographs on the history and symbolism of the three natural kingdoms (animal, plant, and mineral) in human culture. He had completed one on salt (as an example of minerals) and the rose and was working on one on the horse when he died unexpectedly in Frankfort in June 1881.
In looking back, Schleiden has been criticized for being overly fond of his own deductions, and insufficiently eager to test them experimentally. He was regularly described as contentious, stubborn, and arrogant, and it would be interesting to know what was on his mind when he sought out the quiet, pious, and methodical Schwann and expounded his views about the composition of plants. Schwann was able to see the broader implications and formulate them in a systematic manner, which, elaborated by Virchow, was recognized by the scientific community and revolutionized biology.
The Suicidal Lawyer Who Revolutionized Biology
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24.04.2024
In a previous blog, I described the 1873 discovery by Camillo Golgi of a method to visualize neurons and his decades-long debate with co-Nobelist Santiago Ramón y Cajal, which led to our current understanding of neuronal function. All of this work was built in turn upon 'cell theory,' the notion that individual cells represent the basic building blocks of all living things. This is, in a sense, a prequel describing how the German botanist Matthias Jakob Schleiden (1804-1881), troubled by periods of melancholy and a number of challenging personality qualities, came to propose this revolutionary way of understanding the role of cells. His story is also a continuance of earlier posts on figures in science, the arts, and politics who have made remarkable contributions in the course of very troubled lives.
The son of a municipal physician in Hamburg, Schleiden obtained a law degree from the University of Heidelberg in 1827 and returned to practice in his hometown. It turned out to be very unsuccessful; he became despondent and ultimately shot himself. Happily, he survived, though marked for life with a conspicuous scar on his forehead, and wisely realized that a change in profession was in order. He began to study medicine and natural science in Göttingen in 1832, as well as botany in Berlin in 1835. He built on the work of the Scottish botanist Robert Brown (as in the ‘Brownian movement’), who had described the nuclei in plant cells. Schleiden came to believe that nuclei were the key component in the embryonic development of cells. Though he erred in his description of how cells are formed, he was prescient in believing that they represent the basic units of plant life. As such, he believed that........
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