Histology how an independent science emerged in early XIX century. The prehistory of histology was the results of numerous macroscopic (visual) studies of the constituent parts of various animal and plant organisms. The invention of the microscope, the first samples of which were created in early XVII century (G. and 3. Jansen, G. Galileo and others). One of the earliest scientific studies using a microscope of his own design was carried out by the English scientist Robert Hooke (1635-1703). He studied the microscopic structure of many objects. R. Hooke described all the objects studied in the book "Micrography or some physiological descriptions of the smallest bodies made with the help of magnifying glasses ...", published in 1665. From his observations, R. Hooke concluded that bubble-shaped cells, or cells, are widespread, in plant objects and first proposed the term "cell".
In 1671, the English scientist N. Grew (1641-1712) in his book " plant anatomy"Wrote about the cellular structure as a general principle of organization of plant organisms. N. Grew first introduced the term "fabric" to refer to plant mass, since the latter resembled clothing fabrics in its microscopic design. In the same year, the Italian J. Malpighi (1628- 1694) gave a systematic and detailed description cellular (cellular) structure of various plants. In the future, facts gradually accumulated, indicating that not only plant, but also animal organisms consist of cells. In the second half of the 17th century, A. Leeuwenhoek (1632-1723) discovered the world of microscopic animals and for the first time described red blood cells and male sex cells.
Throughout the 18th century there was a gradual accumulation of facts about the cellular structure of plants and animals. Cells of animal tissues were studied and described in detail by the Czech scientist Jan Purkynia (1787-1869) and his students at the beginning of the 19th century.
Of great importance for the development of knowledge about microscopic structure of organisms has further improved microscopes. In the 18th century, microscopes were already being produced in large numbers. They were first brought to Russia from Holland by Peter I. Later, a workshop for the manufacture of microscopes was organized at the Academy of Sciences in St. Petersburg. M.V. did a lot for the development of microscopy in Russia. Lomonosov, who proposed a number of technical improvements in the design of the microscope and its optical system. The second half of the 19th century is notable for the rapid improvement of microscopic technology. New designs of microscopes were created, and thanks to the invention of immersion lenses (water immersion began to be used from 1850, oil immersion - from 1878), the resolution of optical instruments increased tenfold. In parallel with the improvement of the microscope, the technique of preparing microscopic preparations also developed.
If earlier objects examined under a microscope immediately after their isolation from plants or animals without any preliminary preparation, now they began to resort to various methods of processing them, which made it possible to preserve the structure of biological objects. Were suggested different ways material fixation. Chromic, picric, osmic, acetic and other acids, as well as their mixtures, have been used as fixing agents. A simple and in many cases indispensable fixative - formalin - was first used to fix biological objects in 1893.
Manufacturing of drugs, suitable for examination in transmitted light, became possible after the development of methods for pouring pieces into dense media, which made it easier to obtain thin sections. The invention of special structures for cutting - microtomes - in the laboratory of J. Purkins significantly improved the manufacturing technique histological preparations. In Russia, the first microtome was constructed by the Kiev histologist P.I. Peremezhko. To enhance the contrast of the structures, the sections began to be stained with various dyes. Carmine was the first histological dye that stained cell nuclei and was widely used (beginning in 1858). Another nuclear dye - hematoxylin - has been used since 1865, however for a long time its properties have not been fully appreciated. By the second half of the 19th century, aniline dyes were already used, a method was developed for impregnating fabrics with silver nitrate (K. Golgi, 1873) and dyeing nervous tissue methylene blue (A.S. Dogel, A.E. Smirnov, 1887).
Due to the fixation of biological material and obtaining the thinnest colored sections from it, researchers of the late 19th century had the opportunity to penetrate much deeper into the secrets of the structure of tissues and cells, on the basis of which a number of greatest discoveries. So, in 1833, R. Brown discovered a permanent component of the cell - the nucleus. In 1861, M. Schultze approved the view of the cell as "a lump of protoplasm with a nucleus lying inside it." Main constituent parts cells began to count the nucleus and cytoplasm. In the 70s of the XIX century, a group of researchers simultaneously and independently discovered an indirect method of cell division - karyokinesis, or mitosis. In the works of I.D. Chistyakov (1874), O. Buchli (1875), E. Strasburger (1875), W. Meisel (1875), P.I. Peremezhko (1878), V. Schleicher (1878), V. Flemming (1879) and others described and illustrated all stages of indirect cell division. This discovery had great importance to develop knowledge about the cell. It also served as the basis for a deeper study of such an important biological process as fertilization. The study of mitosis and fertilization attracted particular attention of researchers to the cell nucleus and elucidation of its significance in the process of transferring hereditary properties. In 1884, O. Gertwig and E. Strasburger independently put forward the hypothesis that chromatin is the material carrier of heredity.
The object of close attention of scientists is chromosomes. Along with the study of the cell nucleus, the cytoplasm was also subjected to a thorough analysis.
Advances in microscopic technology have led to opening of organelles in the cytoplasm- its constant and highly differentiated elements, having a certain structure and performing vital functions for the cell. In 1875-76. the German biologist O. Hertwig and the Belgian scientist Van Beneden discovered the cell center, or centrosome; and in 1898 by the Italian scientist K. Golgi - the intracellular reticular apparatus (Golgi complex). In 1897, K. Benda - in animal cells, and in 1904 - F. Mewes - in plant cells described chondriosomes, which later became known as mitochondria.
Thus, by the end of the 19th century, on the basis of the successful development of microscopic technology and analysis of data on the microscopic structure of the cell, colossal factual material was accumulated, which made it possible to identify a number of important patterns in the structure and development of cells and tissues. At this time, the doctrine of the cell stood out in an independent biological science - cytology.
This is the science of life. At present, it represents the totality of the sciences of living nature.
Biology studies all manifestations of life: structure, functions, development and origin living organisms, their relationship in natural communities with the environment and with other living organisms.
Since man began to realize his difference from the animal world, he began to study the world around him.
At first, his life depended on it. Primitive people needed to know which living organisms can be eaten, used as medicines, for making clothes and dwellings, and which of them are poisonous or dangerous.
With the development of civilization, a person could afford such a luxury as doing science for educational purposes.
Research the cultures of the ancient peoples showed that they had extensive knowledge about plants and animals and widely applied them in everyday life.
Modern biology - complex the science, which is characterized by the interpenetration of ideas and methods of various biological disciplines, as well as other sciences - primarily physics, chemistry and mathematics.
The main directions of development of modern biology. Currently, three directions in biology can be conditionally distinguished.
First, it is classical biology. It is represented by natural scientists who study the diversity of living nature. They objectively observe and analyze everything that happens in wildlife, study living organisms and classify them. It is wrong to think that in classical biology all discoveries have already been made.
In the second half of the XX century. not only many new species have been described, but also large taxa have been discovered, up to kingdoms (Pogonophores) and even superkingdoms (Archaebacteria, or Archaea). These discoveries forced scientists to take a fresh look at the entire development history living nature, For true natural scientists, nature is a value in itself. Every corner of our planet is unique for them. That is why they are always among those who acutely feel the danger to the nature around us and actively advocate for it.
The second direction is evolutionary biology.
In the 19th century author of the theory natural selection Charles Darwin started out as an ordinary naturalist: he collected, observed, described, traveled, revealing the secrets of wildlife. However, the main result of his work that made him a famous scientist was the theory explaining organic diversity.
Currently, the study of the evolution of living organisms is actively continuing. Synthesis of genetics and evolutionary theory led to the creation of the so-called synthetic theory of evolution. But even now there are still many unresolved questions that evolutionary scientists are looking for answers to.
Created at the beginning of the 20th century. by our outstanding biologist Alexander Ivanovich Oparin, the first scientific theory of the origin of life was purely theoretical. Currently being actively experimental studies of this problem and thanks to the use of advanced physical and chemical methods have already been made important discoveries and we can expect new interesting results.
New discoveries made it possible to supplement the theory of anthropogenesis. But the transition from the animal world to man still remains one of the biggest mysteries of biology.
The third direction is physical and chemical biology, which studies the structure of living objects using modern physical and chemical methods. This is a rapidly developing area of biology, important both in theoretical and practical terms. We can say with confidence that new discoveries await us in physical and chemical biology, which will allow us to solve many problems facing humanity.
The development of biology as a science. Modern biology is rooted in antiquity and is associated with the development of civilization in the Mediterranean countries. We know the names of many outstanding scientists who contributed to the development of biology. Let's name just a few of them.
Hippocrates (460 - c. 370 BC) gave the first regarding detailed description structure of man and animals, pointed to the role of the environment and heredity in the occurrence of diseases. He is considered the founder of medicine.
Aristotle (384-322 BC) divided the world into four kingdoms: the inanimate world of earth, water and air; plant world; the animal world and the human world. He described many animals, laid the foundation for taxonomy. The four biological treatises he wrote contained almost all the information about animals known by that time. The merits of Aristotle are so great that he is considered the founder of zoology.
Theophrastus (372-287 BC) studied plants. He described more than 500 plant species, gave information about the structure and reproduction of many of them, introduced many botanical terms. He is considered the founder of botany.
Gaius Pliny the Elder (23-79) collected information about living organisms known by that time and wrote 37 volumes of the Natural History Encyclopedia. Almost until the Middle Ages, this encyclopedia was the main source of knowledge about nature.
Claudius Galen in his scientific research widely used dissections of mammals. He was the first to make a comparative anatomical description of man and monkey. Studied central and peripheral nervous system. Historians of science consider him the last great biologist of antiquity.
In the Middle Ages, religion was the dominant ideology. Like other sciences, biology during this period had not yet emerged as an independent field and existed in the general mainstream of religious and philosophical views. And although the accumulation of knowledge about living organisms continued, one can speak of biology as a science at that time only conditionally.
The Renaissance is a transitional period from the culture of the Middle Ages to the culture of modern times. The fundamental socio-economic transformations of that time were accompanied by new discoveries in science.
The most famous scientist of this era, Leonardo da Vinci (1452 - 1519), made a certain contribution to the development of biology.
He studied the flight of birds, described many plants, ways of connecting bones in the joints, the activity of the heart and the visual function of the eye, the similarity of human and animal bones.
In the second half of the XV century. natural sciences begin to develop rapidly. This was facilitated by geographical discoveries, which made it possible to significantly expand information about animals and plants. Rapid accumulation scientific knowledge about living organisms led to the division of biology into separate sciences.
In the XVI-XVII centuries. Botany and zoology began to develop rapidly.
The invention of the microscope (early 17th century) made it possible to study the microscopic structure of plants and animals. Microscopically small living organisms, bacteria and protozoa, invisible to the naked eye, were discovered.
A great contribution to the development of biology was made by Carl Linnaeus, who proposed a classification system for animals and plants,
Karl Maximovich Baer (1792-1876) in his works formulated the main provisions of the theory of homologous organs and the law of germinal similarity, which laid the scientific foundations of embryology.
In 1808, in his Philosophy of Zoology, Jean-Baptiste Lamarck raised the question of the causes and mechanisms of evolutionary transformations and outlined the first theory of evolution in time.
The cell theory played a huge role in the development of biology, which scientifically confirmed the unity of the living world and served as one of the prerequisites for the emergence of Charles Darwin's theory of evolution. The zoologist Theodor Ivann (1818-1882) and the botanist Matthias Jakob Schleiden (1804-1881) are considered the authors of the cell theory.
On the basis of numerous observations, Charles Darwin published in 1859 his main work “On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Breeds in the Struggle for Life”, in which he formulated the main provisions of the theory of evolution, proposed the mechanisms of evolution and ways of evolutionary transformations of organisms.
In the 19th century Thanks to the work of Louis Pasteur (1822-1895), Robert Koch (1843-1910), Ilya Ilyich Mechnikov, microbiology took shape as an independent science.
The 20th century began with the rediscovery of Gregor Mendel's laws, which marked the beginning of the development of genetics as a science.
In the 40-50s of the XX century. in biology, the ideas and methods of physics, chemistry, mathematics, cybernetics and other sciences began to be widely used, and microorganisms were used as objects of study. As a result, biophysics, biochemistry, molecular biology, radiation biology, bionics, etc. emerged and rapidly developed as independent sciences. Space exploration contributed to the birth and development of space biology.
In the XX century. the direction of applied research - biotechnology. This trend will undoubtedly develop rapidly in the 21st century. You will learn more about this direction in the development of biology when studying the chapter "Fundamentals of Breeding and Biotechnology".
Currently, biological knowledge is used in all spheres of human activity: in industry and agriculture, medicine and energy.
Ecological research is extremely important. We finally began to realize that the delicate balance that exists on our small planet is easy to destroy. Mankind has faced a daunting task - the preservation of the biosphere in order to maintain the conditions for the existence and development of civilization. Without biological knowledge and special studies to solve it is impossible. Thus, at present, biology has become a real productive force and a rational scientific basis for the relationship between man and nature.
classical biology. Evolutionary biology. Physical and chemical biology.
1. What directions in the development of biology can you single out?
2. What great scientists of antiquity made a significant contribution to the development of biological knowledge?
3. Why in the Middle Ages it was possible to speak about biology as a science only conditionally?
4. Why is modern biology considered a complex science?
5. What is the role of biology in modern society?
6. Prepare a message on one of the following topics:
7. The role of biology in modern society.
8. The role of biology in space research.
9. The role of biological research in modern medicine.
10. The role of outstanding biologists - our compatriots in the development of world biology.
How much the views of scientists on the diversity of living things have changed can be demonstrated by the example of the division of living organisms into kingdoms. Back in the 40s of the XX century, all living organisms were divided into two kingdoms: Plants and Animals. The plant kingdom also included bacteria and fungi. Later, a more detailed study of organisms led to the allocation of four kingdoms: Prokaryotes (Bacteria), Fungi, Plants and Animals. This system given in school biology.
In 1959, it was proposed to divide the world of living organisms into five kingdoms: Prokaryotes, Protists (Protozoa), Fungi, Plants and Animals.
This system is often given in biological (especially translated) literature.
Other systems have been developed and continue to be developed, including 20 or more kingdoms. For example, it is proposed to distinguish three superkingdoms: Prokaryotes, Archaea (Archaebacteria) and Eukaryotes. Each superkingdom includes several kingdoms.
Kamensky A. A. Biology grade 10-11
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REPORT on Biology of a 6th grade student
For a long time, a person lived surrounded by invisible creatures, used their waste products (for example, when baking bread from sour dough, making wine and vinegar), suffered when these creatures caused illnesses or spoiled food supplies, but did not suspect their presence . I didn't suspect because I didn't see it, and I didn't see it because the sizes of these micro creatures were much lower than the limit of visibility that the human eye is capable of. It is known that a person with normal vision at the optimal distance (25–30 cm) can distinguish an object 0.07–0.08 mm in size in the form of a point. Smaller objects cannot be seen. This is determined by the structural features of his organ of vision.
Approximately at the same time when the exploration of space with the help of telescopes began, the first attempts were made to reveal, with the help of lenses, the secrets of the microworld. So, during archaeological excavations in Ancient Babylon, biconvex lenses were found - the simplest optical devices. The lenses were made from polished mountain crystal. It can be considered that with their invention man took the first step on the way to the microworld.
The simplest way to enlarge the image of a small object is to observe it with a magnifying glass. A magnifying glass is a converging lens with a small focal length (usually no more than 10 cm) inserted into the handle.
telescope maker Galileo V 1610
In 1993, he discovered that, when wide apart, his spotting scope made it possible to greatly enlarge small objects. It can be considered the inventor of the microscope consisting of positive and negative lenses.
A more advanced tool for observing microscopic objects is simple microscope. When these devices appeared, it is not known exactly. At the very beginning of the 17th century, several such microscopes were made by a spectacle craftsman Zacharias Jansen from Middelburg.
In the essay A. Kircher, released in 1646 year, contains a description the simplest microscope named by him "flea glass". It consisted of a magnifying glass embedded in a copper base, on which an object table was fixed, which served to place the object in question; at the bottom there was a flat or concave mirror, reflecting the sun's rays onto an object and thus illuminating it from below. The magnifying glass was moved by means of a screw to the object table until the image became distinct and clear.
First great discoveries were just made using a simple microscope. IN mid-seventeenth centuries of brilliant success was achieved by the Dutch naturalist Anthony Van Leeuwenhoek. For many years, Leeuwenhoek perfected himself in the manufacture of tiny (sometimes less than 1 mm in diameter) biconvex lenses, which he made from a small glass ball, which in turn was obtained by melting a glass rod in a flame. Then this glass ball was ground on a primitive grinding machine. During his life, Leeuwenhoek made at least 400 such microscopes. One of them, kept in the University Museum in Utrecht, gives more than 300x magnification, which was a huge success for the 17th century.
At the beginning of the 17th century, there were compound microscopes composed of two lenses. The inventor of such a complex microscope is not exactly known, but many facts indicate that he was a Dutchman. Cornelius Drebel, who lived in London and was in the service of English king James I. In the compound microscope was two glasses: one - the lens - facing the object, the other - the eyepiece - facing the eye of the observer. In the first microscopes, a biconvex glass served as an objective, which gave a real, enlarged, but inverse image. This image was examined with the help of an eyepiece, which thus played the role of a magnifying glass, but only this magnifying glass served to magnify not the object itself, but its image.
IN 1663 microscope Drebel was improved English physicist Robert Hooke, who introduced a third lens into it, called the collective. This type of microscope gained great popularity, and most of the microscopes of the late 17th - first half of the 8th century were built according to its scheme.
Microscope device
A microscope is an optical instrument designed to study magnified images of micro-objects that are invisible to the naked eye.
The main parts of a light microscope (Fig. 1) are an objective and an eyepiece enclosed in a cylindrical body - a tube. Most models designed for biological research come with three lenses with different focal lengths and a rotating mechanism designed for quick change - a turret, often called a turret. The tube is located on the top of a massive stand, including the tube holder. Slightly below the objective (or turret with multiple objectives) is an object stage, on which slides with test samples are placed. Sharpness is adjusted using a coarse and fine adjustment screw, which allows you to change the position of the stage relative to the objective.
In order for the sample under study to have sufficient brightness for comfortable observation, the microscopes are equipped with two more optical units (Fig. 2) - an illuminator and a condenser. The illuminator creates a stream of light that illuminates the test preparation. In classical light microscopes, the design of the illuminator (built-in or external) involves a low-voltage lamp with a thick filament, a converging lens, and a diaphragm that changes the diameter of the light spot on the sample. The condenser, which is a converging lens, is designed to focus the illuminator beams on the sample. The condenser also has an iris diaphragm (field and aperture), which controls the intensity of illumination.
When working with light-transmitting objects (liquids, thin sections of plants, etc.), they are illuminated by transmitted light - the illuminator and condenser are located under the object table. Opaque samples should be illuminated from the front. To do this, the illuminator is placed above the object stage, and its beams are directed to the object through the lens using a translucent mirror.
The illuminator may be passive, active (lamp), or both. The simplest microscopes do not have lamps to illuminate samples. Under the table they have a double-sided mirror, in which one side is flat and the other is concave. In daylight, if the microscope is near a window, you can get pretty good illumination using a concave mirror. If the microscope is in a dark room, a flat mirror and an external illuminator are used for illumination.
The magnification of a microscope is equal to the product of the magnification of the objective and the eyepiece. With an eyepiece magnification of 10 and an objective magnification of 40, the total magnification factor is 400. Usually, objectives with a magnification of 4 to 100 are included in a research microscope kit. A typical microscope objective kit for amateur and educational research (x4, x10 and x40), provides increase from 40 to 400.
Resolution is another important characteristic of a microscope, which determines its quality and the clarity of the image it forms. The higher the resolution, the more fine details can be seen at high magnification. In connection with resolution, one speaks of "useful" and "useless" magnification. “Useful” is the maximum magnification at which the maximum image detail is provided. Further magnification (“useless”) is not supported by the resolution of the microscope and does not reveal new details, but it can adversely affect the clarity and contrast of the image. Thus, the limit of useful magnification of a light microscope is not limited by the overall magnification factor of the objective and the eyepiece - it can be made arbitrarily large if desired - but by the quality of the optical components of the microscope, that is, the resolution.
The microscope includes three main functional parts:
1. Lighting part
Designed to create a light flux that allows you to illuminate the object in such a way that the subsequent parts of the microscope perform their functions with the utmost accuracy. The illuminating part of a transmitted light microscope is located behind the object under the objective in direct microscopes and in front of the object above the objective in inverted ones.
The lighting part includes a light source (a lamp and an electric power supply) and an optical-mechanical system (collector, condenser, field and aperture adjustable / iris diaphragms).
2. Playback part
Designed to reproduce an object in the image plane with the image quality and magnification required for research (i.e., to build such an image that reproduces the object as accurately as possible and in all details with the resolution, magnification, contrast and color reproduction corresponding to the microscope optics).
The reproducing part provides the first stage of magnification and is located after the object to the image plane of the microscope. The reproducing part includes a lens and an intermediate optical system.
Modern microscopes of the latest generation are based on optical systems of lenses corrected for infinity.
This additionally requires the use of so-called tube systems, which “collect” parallel beams of light coming out of the objective in the image plane of the microscope.
3. Visualizing part
Designed to obtain a real image of an object on the retina, film or plate, on the screen of a television or computer monitor with additional magnification (the second stage of magnification).
The imaging part is located between the image plane of the lens and the eyes of the observer (camera, camera).
The imaging part includes a monocular, binocular or trinocular visual attachment with an observation system (eyepieces that work like a magnifying glass).
In addition, this part includes systems of additional magnification (systems of a wholesaler / change of magnification); projection nozzles, including discussion nozzles for two or more observers; drawing devices; image analysis and documentation systems with appropriate matching elements (photo channel).
photo from scop-pro.fr
Microscopy technology has opened up new possibilities in medical and laboratory practice. Today, neither diagnostic studies nor surgical interventions can do without special optics. The most significant role of microscopes in dentistry, ophthalmology, microsurgery. This is not just about improving visibility and facilitating work, but about a fundamentally new approach to research and operations.
impact on fine structures cellular level means that the patient will more easily endure the intervention, recover faster, and will not suffer damage to healthy tissues and complications. Behind all these advantages of modern medicine is often a microscope - a powerful high-tech device designed using recent achievements optics.
Depending on the purpose, microscopes are divided into:
- laboratory;
- dental;
- surgical;
- ophthalmic;
- otolaryngological.
Optical systems for biochemical, hematological, dermatological, cytological studies are functionally different from medical ones. Ophthalmic microscopes are recognized as the most advanced and powerful - with their help, it was possible to make a radical breakthrough in the treatment of cataracts, hyperopia, myopia, astigmatism. Operations at the micron level, performed under 40x magnification, are comparable in invasiveness to an injection, the patient recovers after surgery in a matter of days.
No less interesting are those that allow, under 25x magnification, to accurately treat dental canals and other smallest structures that are not visible to the human eye. Using the latest optics, dentists almost always manage to provide high-quality treatment and save the tooth.
Magnifying devices for microsurgery are characterized by an extended field of view, increased image sharpness, and the possibility of smooth or stepwise adjustment of the magnification. All this provides the best visibility conditions for the surgeon and assistants.
It is important that the new generation of instruments for microscopy is as convenient as possible to use: working with magnifying optics is simple and does not require much effort or special skills. Due to the built-in lighting system and the convenient shape of the eyepiece, the specialist does not experience fatigue and discomfort even during long continuous work.
A microscope is a fragile instrument that needs to be handled with care. This is especially true of lenses: it is undesirable to touch the optical surfaces with your hands; a special brush and soft wipes soaked in ethyl alcohol are used to clean the device.
Rooms containing microscopes should be maintained at room temperature and low humidity (less than 60%).
First microscopists second half of the 17th century. - physicist R. Hooke, anatomist M. Malpighi, botanist N. Gru, amateur optician A. Leeuwenhoek and others described the structure of the skin, spleen, blood, muscles, seminal fluid, etc. using a microscope. Each study was essentially a discovery, which did not get along well with the metaphysical view of nature that has evolved over the centuries. The random nature of discoveries, the imperfection of microscopes, the metaphysical worldview did not allow for 100 years (from the middle of the 17th century to the middle of the 18th century) to make significant steps forward in the knowledge of the laws of the structure of animals and plants, although attempts were made to generalize (theories of "fibrous" and " granular structure of organisms, etc.).
The discovery of the cellular structure occurred at a time in the development of mankind, when experimental physics began to claim to be called the mistress of all sciences. In London, a society of the greatest scientists was created, who focused on improving the world on specific physical laws. At the meetings of the community members, there were no political debates, only various experiments were discussed and research on physics and mechanics was shared. Times were turbulent then, and scientists observed very strict secrecy. The new community began to be called the "college of the invisible." The first who stood at the origins of the creation of the society was Robert Boyle, Hooke's great mentor. The Board produced the necessary scientific literature. The author of one of the books was Robert Hook, who was also a member of this secret scientific community. Hooke already in those years was known as the inventor of interesting devices that made it possible to make great discoveries. One of these devices was microscope.
One of the first creators of the microscope was Zacharius Jansen who created it in 1595. The idea of the invention was that two lenses (convex) were mounted inside a special tube with a retractable tube to focus the image. This device could increase the studied objects by 3-10 times. Robert Hooke improved this product, which played leading role in the upcoming opening.
Robert Hooke for a long time observed various small specimens through the created microscope, and once he took an ordinary cork from a vessel for viewing. Having examined a thin section of this cork, the scientist was surprised at the complexity of the structure of the substance. An interesting pattern of many cells appeared to his eyes, surprisingly similar to a honeycomb. Since cork is a vegetable product, Hooke began to study sections of plant stems with a microscope. Everywhere a similar picture was repeated - a set of honeycombs. The microscope showed many rows of cells, which were separated by thin walls. Robert Hooke called these cells cells. Subsequently formed whole science about cells, which is called cytology. Cytology includes the study of the structure of cells and their vital activity. This science is used in many areas, including medicine and industry.
With name M. Malpighi This outstanding biologist and physician is associated with an important period of microscopic studies of the anatomy of animals and plants.
The invention and improvement of the microscope allowed scientists to discover
a world of extremely small creatures, completely different from those
which are visible to the naked eye. Having received a microscope, Malpighi made a number of important biological discoveries. At first he considered
everything that came to hand:
- insects,
- light frogs,
- blood cells,
- capillaries,
- skin,
- liver,
- spleen
- plant tissues.
In the study of these subjects, he reached such perfection that he became
one of the founders of microscopic anatomy. Malpighi was the first to use
microscope for the study of blood circulation.
Using a 180x magnification, Malpighi made a discovery in the theory of blood circulation: looking at a frog lung preparation under a microscope, he noticed air bubbles surrounded by a film, and small blood vessels, saw an extensive network of capillary vessels connecting arteries to veins (1661). Over the next six years, Malpighi made the observations that he described in scientific papers who brought him fame as a great scientist. Malpighi's reports on the structure of the brain, tongue, retina, nerves, spleen, liver, skin, and on the development of the embryo in a chicken egg, as well as on the anatomical structure of plants, testify to very careful observations.
Nehemiah Gru(1641 - 1712). English botanist and physician, microscopist,
founder of plant anatomy. The main works are devoted to the issues of structure and gender of plants. Along with M. Malpighi was the founder
plant anatomy. First described:
- stomata,
- radial arrangement of xylem in roots,
- morphology of vascular tissue in the form of a dense formation in the center of the stem of a young plant,
- the process of forming a hollow cylinder in old stems.
He introduced the term "comparative anatomy", introduced the concepts of "tissue" and "parenchyma" into botany. Studying the structure of flowers, I came to the conclusion that they are the organs of fertilization in plants.
Leeuwenhoek Anthony(October 24, 1632–August 26, 1723), Dutch naturalist. He worked in a textile shop in Amsterdam. Back in Delft, in his spare time he worked as a lens grinder. In total, during his life, Leeuwenhoek made about 250 lenses, achieving a 300-fold increase and achieved great perfection in this. The lenses he made, which he inserted into metal holders with a needle attached to them to put the object of observation, gave a magnification of 150–300 times. With the help of such "microscopes" Leeuwenhoek first observed and sketched:
- spermatozoa (1677),
- bacteria (1683),
- erythrocytes,
- protozoa,
- individual plant and animal cells,
- eggs and fetuses
- muscle tissue,
- many other parts and organs of more than 200 species of plants and animals.
First described parthenogenesis in aphids (1695–1700).
Leeuwenhoek stood on the positions of preformism, arguing that the formed embryo is already contained in the "animalcule" (spermatozoon). He denied the possibility of spontaneous generation. He described his observations in letters (up to 300 in total), which he sent mainly to the Royal Society of London. Following the movement of blood through the capillaries, he showed that capillaries connect arteries and veins. For the first time he observed erythrocytes and found that in birds, fish and frogs they have an oval shape, while in humans and other mammals they are disc-shaped. He discovered and described rotifers and a number of other small freshwater organisms.
The use of an achromatic microscope in scientific research has served as a new impetus for the development of histology. At the beginning of the XIX century. the first image of plant cell nuclei was made. J. Purkinje(in 1825-1827) described the nucleus in the ovum of a chicken, and then the nuclei in the cells of various animal tissues. Later, he introduced the concept of "protoplasm" (cytoplasm) of cells, characterized the form nerve cells, structure of glands, etc.
R. Brown concluded that the nucleus is an essential part of the plant cell. Thus, gradually began to accumulate material on the microscopic organization of animals and plants and the structure of "cells" (cellula), seen for the first time by R. Hooke.
The creation of the cell theory had a huge progressive impact on the development of biology and medicine. In the middle of the XIX century. began a period of rapid development of descriptive histology. Based on the cellular theory, the composition of various organs and tissues and their development were studied, which made it possible even then to create a microscopic anatomy in basic terms and to refine the classification of tissues, taking into account their microscopic structure (A. Kölliker and others).
