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MOST IMPORTANT SCIENTIFIC DISCOVERIES
Plant classification. History and essence of scientific discovery
Directory / The most important scientific discoveries In the XNUMXth century, when the biological sciences were still in their infancy, there was no division of the science of nature into many separate specialized sciences. As knowledge accumulated, a huge amount of new material made research more and more difficult, suppressed science, and at the beginning of the XNUMXth century terrible chaos reigned in descriptive zoology and botany. The reason for such a sad state of these sciences was the lack of clear and precise methods of research. Two main shortcomings hindered their further development and produced endless confusion: the lack of accurate descriptions and designations of various species, on the one hand, and inept and incorrect classification, on the other. The concept of a species in the sense in which it now exists in science was developed for the first time in the second half of the XNUMXth century by the Englishman Ray. When we have in front of us a certain number of specimens of an animal, almost similar in everything to each other, but some of them differ from the rest in some permanent feature, we single them out and attribute them to a special species - unless, of course, this difference is not depends on the sex or age of the animal. These distinguishing features are species characteristics and are strictly inherited. This rule applies equally to animals and plants. "Forms representing species differences between themselves retain them unchanged, and one species (of plants) never comes from the seeds of another, and vice versa," says Ray. This definition contained the germ of the doctrine of the immutability of species, which later, in the era Linnaeus и Cuvier, turned into scientific dogma and reigned in science for a long time, until Darwin did not end his reign. Thus, zoology and botany of that time were mainly concerned with the study and description of species, but great confusion reigned in their recognition. The descriptions that the author gave of new animals or plants were usually so inconsistent and inaccurate that later it was often not possible to find out what kind of species he was talking about, and it was difficult to recognize the described form in nature. The absence of proper names for the vast majority of newly studied organisms entailed polysyllabic, clumsy definitions by which one species differed in the literature from another. The second main malady of the then science was the lack of a more or less tolerable and accurate classification. There was an urgent need to arrange them in such an order that a given plant, for example, could always be found in a book, knowing in advance where to look for it; so that, having an unknown species in front of you, you can easily compare it with descriptions of all similar species and establish whether it is a new species or already described. It is clear that already the most ancient scientists in the natural sciences, dividing their material into certain categories, determined certain groups of forms that were similar to each other. But ignorance of the structure of organisms and the significance of individual organs, the lack of accurate observations, the inability to distinguish important and permanent features from unimportant and variable ones made any classification random, arbitrary and completely inaccurate. Plants that are very similar to each other often belonged to different groups. At the end of the XNUMXth century, Ray, Tournefort and others made several attempts to establish order in the distribution of plants, but these attempts were not particularly successful. The division was usually based on the structure of some one organ, for example, a fruit or a flower. Tournefort, whose system was particularly successful, divided plants into classes chiefly on the basis of flower appearance. But in most cases, the shape of the flower is extremely variable even in closely related forms, and, in addition, it is more than difficult to strictly determine the shape of the corolla as funnel-shaped, bell-shaped, or another. These basic shortcomings of systematic botany were corrected by the genius of Carl Linnaeus. Remaining on the same ground of the study of nature, on which his predecessors and contemporaries stood, he was a powerful reformer of science. Its merit is purely methodological. Linnaeus used the doctrine of the species in the form expressed by Ray, and introduced, to designate individual species and distinguish them from each other, a binary (double) nomenclature, which has been preserved in science to this day. Carl Linnaeus (1707–1778) was born in Sweden, in the village of Rozgult. When the boy was ten years old, he was sent to an elementary school in the town of Vexie. After graduating from high school, Karl enters Lund University, but soon moves from there to one of the most prestigious universities in Sweden - Uppsala. Linnaeus was only 23 years old when the professor of botany Oluas Celsius took him to be his assistant, after which Karl himself, while still a student, began teaching at the university. In the spring of 1735, Linnaeus arrived in Holland, in Amsterdam. In the small university town of Garderwick, he passed the exam and on June 24 he defended his dissertation on a medical topic - about fever - prepared by him back in Sweden. In the same place, Linnaeus compiled and printed the first draft of his famous work "Systema naturae", which laid the foundation for systematic zoology and botany in the modern sense. With this edition, a series of rapid scientific successes of Linnaeus begins. In his new works, published in 1736-1737, his main and most fruitful ideas were already contained in a more or less finished form: a system of generic and specific names, improved terminology, an artificial system of the plant kingdom. At this time, he received a brilliant offer to become the personal physician of George Cliffort with a salary of 1000 guilders and a full allowance. On his estate Gartekampe, near Harlem, there was a garden famous in Holland, in which, regardless of the costs, he was engaged in the cultivation and acclimatization of foreign plants on a huge scale - plants of Southern Europe, Asia, Africa, America. At the garden, he had both herbariums and a rich botanical library. All this contributed to the scientific work of Linnaeus. Despite the successes that surrounded Linnaeus in Holland, little by little he begins to pull home. In 1738 he returned to his homeland. In a short period of his life in Stockholm, Linnaeus took part in the founding of the Stockholm Academy of Sciences. In 1742, Linnaeus's dream came true: he became a professor of botany at his native university. He occupied the department for more than thirty years and left it only shortly before his death. But the main business of his life, Linnaeus still considered the systematization of plants. The main work "The System of Plants" took as much as 25 years, and only in 1753 did he publish this work. The idea of Linnaeus was as follows: the scientist connected species similar to each other into genera. Several species that are similar to each other in their main features and differ only in minor features are assigned to one genus and receive one common name. So, for example, the generic name for currants would be Ribes. Separate species of this genus are designated by adding the specific names to the generic. So red currant will be Ribes rubrum, black currant will be Ribes nigrum. Gooseberries are so close to these shrubs that they are assigned to the same genus and are called Ribes grossularia. Before Linnaeus, however, each species differed from its adjacent ones by a clumsy characteristic, a brief description, always insufficient for a complete definition. Here is how, for example, the common wild rose was designated by ancient botanists: rosa silvestris vulgaris flore odorato incarnato (he also called it Rosa canina, and no other rose could be meant by this name. With double nomenclature, meeting the name of an unknown plant, by its generic name we we can immediately see with which species it has the most similarities. The Linnaean system is of great practical convenience. Since there are, of course, incomparably fewer genera on Earth than species, the need to create new names is greatly facilitated. In different genera, the same species names can be used without fear of causing confusion: the same adjectives are found in taxonomy at every step, without complicating anyone. But in order for the new nomenclature to be fruitful, it was necessary that the species that received the conditional name, at the same time, be so accurately and in detail described that they could not be confused with other species of the same genus. Linnaeus did just that. He was the first to introduce a strictly defined, precise language and a precise definition of features into science. The technical terminology, which is always so intimidating to beginners on their first acquaintance with botany or zoology, is the only way to navigate the mass of organic forms and is a precious key to their study. Linnaeus was the creator of a strict scientific language in zoology and botany. Having thus developed the foundations for the scientific definition of species, Linnaeus described many plant and animal forms in his writings. He himself set an example of how to use the scientific language he created: his brief species diagnoses are concise and accurate. Linnaeus was the first to create a convenient, precise and strict system of plants, albeit on an artificial basis. It is artificial because, when determining the similarity of plants and classifying them, he did not take into account all the similarities and differences, not the totality of all the morphological characteristics of a plant - a totality that alone can determine the true relationship of two forms, but built his entire system solely on the basis of one only an organ - a flower. In this his system is similar to Tournefort's. However, instead of a vague, indefinite and deceptive general form, he took number as the basis for division - and in this way he created a simple, witty and accurate key to the study of botanical systematics. The general idea of the methods of reproduction of plants, of the existence in them, as in animals, of male and female sex and sexual reproduction, existed even among the ancients. In the XNUMXth century, a number of studies by various scientists were devoted to the issue of plant reproduction, thanks to which the male and female organs of the flower - stamens and pistils - were discovered and the act of pollination was described. Linnaeus, while still a student at Uppsala, got acquainted with the work of Vaillant, a student of Tournefort, where new data on plant reproduction were presented. Even then, apparently, Linnaeus had the idea to use these important organs to classify plants. The execution of this idea led him to the famous artificial plant system. Its principle is extremely clear and simple: the division is based on the stamens and pistils of a flower. Separate classes are characterized by the number and arrangement of stamens. First dividing the plants into phanerogamous (with a flower, stamens and pistils) and cryptogamous (flowerless), Linnaeus created from the first 23 classes, and combined the latter into one. The practical advantages of the new system were very great. Any new kind of plant easily found a place in it. The identification of plants, their systematic distribution was extremely facilitated. All this contributed to its rapid spread. The disadvantage of this system is that it is artificial. The number of stamens is not closely related to the whole organization of the plant, and therefore the classes of Linnaeus are essentially a disorderly kaleidoscope of forms, mechanically squeezed into one frame. The application of such a one-sided criterion often led to the forcible division of very close, undoubtedly related forms into different classes. Linnaeus was clearly aware of these shortcomings. He himself regarded his system as provisional, as a convenient method for studying plants in anticipation of a more natural classification. Therefore, he often himself violates the strictness of his system, yielding to the requirement of a close similarity of organisms, their kinship. The "natural system", which dominated the minds of scientists of the last century, expressed an unconscious search for kinship, a common origin of plants. Linnaeus did not discover new areas of knowledge and hitherto unknown laws of nature, but he created a new method, clear, logical, and with the help of it brought light and order to where chaos and confusion reigned before him, which gave a huge impetus to science, paving the way in a powerful way for further research. A huge number of organic forms, crushing science with their richness and defying description and distribution, with the help of the methods created by Linnaeus, underwent rapid development and could easily be brought into a system convenient for study. This was a necessary step in science, without which further progress would not have been possible. Author: Samin D.K.
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