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1.
This article revisits the development of the protoplasm concept as it originally arose from critiques of the cell theory, and examines how the term “protoplasm” transformed from a botanical term of art in the 1840s to the so-called “living substance” and “the physical basis of life” two decades later. I show that there were two major shifts in biological materialism that needed to occur before protoplasm theory could be elevated to have equal status with cell theory in the nineteenth century. First, I argue that biologists had to accept that life could inhere in matter alone, regardless of form. Second, I argue that in the 1840s, ideas of what formless, biological matter was capable of dramatically changed: going from a “coagulation paradigm” (Pickstone, 1973) that had existed since Theophrastus, to a more robust conception of matter that was itself capable of movement and self-maintenance. In addition to revisiting Schleiden and Schwann’s original writings on cell theory, this article looks especially closely at Hugo von Mohl’s definition of the protoplasm concept in 1846, how it differed from his primordial utricle theory of cell structure two years earlier. This article draws on Lakoff and Johnson’s theory of “ontological metaphors” to show that the cell, primordial utricle, and protoplasm can be understood as material container, object, and substance, and that these overlapping distinctions help explain the chaotic and confusing early history of cell theory.  相似文献   

2.
C. Bouchara  P. Mazet  D. Cohen 《PSN》2010,8(3):163-169
The recent discovery of a drawing of the mind sheds new light on Charcot’s contribution to the discovery of the unconscious. This particular drawing, given by his son Jean-Baptiste, was found in Charcot’s personal notes related to a lecture he gave in June 1892 and was kept in the Salpêtrière historical collection of the University Pierre and Marie Curie. Is this drawing an anticipation of Freud’s first topology of the Unconscious? This is the main issue raised. In order to understand its full meaning, we will focus on Charcot’s scientific thoughts, the specific position he held on hypnosis, his studies on the force of the idea and experimental paralysis, his relationships with Pierre Janet and Sigmund Freud during the years 1885–1992, and finally, his view on Sigmund Freud that is shared in their correspondences.  相似文献   

3.
THE PARASPORAL BODY OF BACILLUS LATEROSPORUS LAUBACH   总被引:7,自引:5,他引:2       下载免费PDF全文
On sporulation the slender vegetative rods swell and form larger spindle-shaped cells in which the spores are formed. When the spores mature they lie in a lateral position cradled in canoe-shaped parasporal bodies which are highly basophilic and can be differentiated from the surrounding vegetative cell cytoplasm with dilute basic dyes. On completion of sporulation the vegetative cell protoplasm and the cell wall lyse, leaving the spore cradled in its parasporal body. This attachment continues indefinitely on the usual culture medium and even persists after the spores have germinated. In thin sections of sporing cells the bodies are differentiated from the cell protoplasm by differences in structure. Whereas the protoplasm has a granular appearance, in both longitudinal and cross-sections the parasporal body comprises electron-dense lamellae running parallel with the membranes of the spore coat and less electron-dense material in the interstices of the lamellae. The inner surface of the body is contiguous with that of the spore coat as if it were part of the spore, rather than a separate body attached to the spore. The staining reactions of the parasporal body are not consistent with those of any substance described in bacteria. With Giemsa the bodies stain like chromatin, but the Feulgen reaction indicates that they do not contain the requisite nucleic acid. With an aqueous solution of toluidine blue they stain metachromatically, but with an acidified solution the results are variable. Neisser's stain for polyphosphate is negative. The basophilic substance is removed from the body with some organic solvents. This basophilic substance has not been specifically identified with any material seen in ultrathin sections, but it is suggested that it might be the less electron-dense material in the interstices of the lamellar structure. In contrast to the spore coat of B. laterosporus, those of its two relatives B. brevis and B. circulans take up basic stain like the parasporal body. Thin spore sections of these species have shown that the walls are thicker than those surrounding the spores of B. laterosporus, and it is suggested that the outer stainable layer of brevis and circulans spores is an accessory coat which in laterosporus may have been deformed to give a parasporal body.  相似文献   

4.
The experiments seem to indicate that the toxicity of HCN and KCN for amebæ is due to their effect on the cell membrane and not on the internal protoplasm. Concentrated solutions (N/10–N/300) of HCN or KCN produce an initial increase in viscosity of the protoplasm of amebæ (immersed) which is followed by liquefaction and disintegration of the cell. Dilute solutions of HCN or KCN decrease the viscosity of the protoplasm of amebæ. Injections of HCN or KCN into amebæ produce a reversible decrease in viscosity of the protoplasm.  相似文献   

5.
6.
An electrical current passing through a living plant flows partly through the cell wall and partly through the protoplasm. The relative amounts of these two portions of the current can be calculated. The outcome of such calculations shows that the conclusions drawn from the study of the resistance of the tissue as a whole apply also to the resistance of the protoplasm, and consequently to the permeability of the protoplasm to ions.  相似文献   

7.
Jacqueline Carroy 《PSN》2007,5(2):97-108
This paper sets out to place The Interpretation of Dreams within an historical context. It argues that it is impossible to have complete confidence in Freud’s words when, in his letters to Wilhelm Fliess, he characterized himself as a mere discoverer. In reality, Freud also felt he belonged to a learned community of dream specialists, whom I call “dreaming scientists” and “scientific dreamers”. Here, I offer, as example, a portrait of Freud as a reader of two French authors, Alfred Maury, and, indirectly, Léon Hervey de Saint-Denys. I analyze how Freud positioned himself as Maury’s successor and sometimes experienced dreams like Hervey de Saint-Denys. The premise of this work is that we must set aside Freud if we want to venture into the learned dream culture peculiar to the 19th century. Only afterwards can we return to Freud and place him in this context as a creative heir.  相似文献   

8.
On October 7, 2008, the world lost one of the most influential scientists of the 20th century, and modern cell biology lost its founder. George E. Palade, recipient of the Nobel Prize in 1974 for his work that established our basic understanding of cellular organization, died at the age of 95 after a long illness.  相似文献   

9.
Keith Porter culminated his stellar career as the founding father of biological electron microscopy by acquiring, in the late 1970s, a high-voltage electron microscope (HVEM). With this magnificent instrument he examined whole-mounts of cultured cells, and perceived within them a structured cytoplasmic matrix he named the "microtrabecular lattice". Over the next decade Porter published a series of studies, together with a team of outstanding young colleagues, which elaborated his broader "microtrabecular concept." This concept posited that microtrabeculae were real physical entities that represented the fundamental organization the cytoplasm, and that they were the physical basis of cytoplasmic motility and of cell-shape determination. The present review presents Porter's original images of microtrabeculae, after conversion to a more interpretable "digital-anaglyph" form, and discusses the rise and fall of the microtrabecular concept. Further, it explains how the HVEM images of microtrabeculae finally came to be considered as an artifact of the preparative methods Porter used to prepare whole cells for HVEM. Still, Keith's "microtrabecular concept" foretold of our current appreciation of the complexity and pervasiveness of the cytoskeleton, which has now been found by more modern methods of EM to actually be the fundamental organizing principle of the cytoplasmic matrix. During the impending eclipse of Porter's microtrabecular concept in the late 1980s, many of Keith's colleagues fondly described the cell as being filled, not with protoplasm, but with "Porterplasm." Despite the fact that Keith's view was clouded by the methods of his time, it would be fitting and apt to retain this name, still today, for the ordered matrix of cytoskeletal macromolecules that exists in the living cell. In the end, the story of what happened to Porter's microtrabecular concept should be an object lesson in scientific hubris that should humble and inform all of us in cell biology, even today--particularly when we begin to think that our most recent methods and observations are achieving "the last word".  相似文献   

10.
Eduard Strasburger Eduard Strasburger, director of the Institute of Botany and the Botanical Garden at the University of Bonn from 1881 to 1912, was one of the most admirable scientists in the field of plant biology, not just as the founder of modern plant cell biology but in addition as inspirator for sensory plant biology. He contributed to plant cell biology by discovering the discrete stages of karyokinesis and cytokinesis in algae and land plants, describing cytoplasmic streaming in different systems, and reporting on the growth of the pollen tube into the embryo sac and guidance of the tube by the synergides. Strasburger attracted attention to many biological phenomena which remain hot spots even in current plant cell biology research, e.g., mechanisms of cell plate formation, vesicle trafficking as a basis for most important developmental processes, structure and function of the plasmodesmata, and signaling related to fertilization. By his early industrial cooperation, internationality, integrating research profile and public teaching he fulfills even today's most admired and desirable qualities of a distinguished and highly honored academic scholar and frontier scientist.  相似文献   

11.
Friederich Wilhelm Benedikt Hofmeister (1824-1877) stands as one of the true giants in the history of biology and belongs in the same pantheon as Darwin and Mendel. Yet by comparison, he is virtually unknown. If he is known at all, it is for his early work on flowering plant embryology and his ground-breaking discovery of the alternation of generations in plants, which he published at age 27 in 1851. Remarkable as the latter study was, it was but a prelude to the more fundamental contributions he was to make in the study of plant growth and development expressed in his books on plant cell biology (Die Lehre von der Pfanzenzelle, 1867) and plant morphology (Allgemeine Morphologie der Gewächse, 1868). In this article we review his remarkable life and career, highlighting the fact that his scientific accomplishments were based largely on self-education in all areas of biology, physics, and chemistry. We describe his research accomplishments, including his early embryological studies and their influence on Mendel's genetic studies as well as his elucidation of the alternation of generations, and we review in detail his cell biology and morphology books. It is in the latter two works that Hofmeister the experimentalist and biophysicist is most manifest. Not only did Hofmeister explore the mechanisms of cytoplasmic streaming, plant morphogenesis, and the effects of gravity and light on their development, but in each instance he developed a biophysical model to integrate and interpret his wealth of observational and experimental data. Because of the lack of attention to the cell and morphology books, Hofmeister's true genius has not been recognized. After studying several evaluations of Hofmeister by contemporary and later workers, we conclude that his reputation became eclipsed because he was so far ahead of his contemporaries that no one could understand or appreciate his work. In addition, his basically organismic framework was out of step with the more reductionistic cytogenetic work that later came in vogue. We suggest that the translation of the cell and morphology books in English would help re-establish him as one of the most notable scientists in the history of plant biology.  相似文献   

12.
Famously, James Watson credited the discovery of the double-helical structure of DNA in 1953 to an X-ray diffraction photograph taken by Rosalind Franklin. Historians of molecular biology have long puzzled over a remarkably similar photograph taken two years earlier by the physicist and pioneer of protein structure William T. Astbury. They have suggested that Astbury's failure to capitalize on the photograph to solve DNA's structure was due either to his being too much of a physicist, with too little interest in or knowledge of biology, or to his being misled by an erroneous theoretical model of the gene. Drawing on previously unpublished archival sources, this paper offers a new analysis of Astbury's relationship to the problem of DNA's structure, emphasizing a previously overlooked element in Astbury's thinking: his concept of biological specificity.  相似文献   

13.
John Heuser is being honored in this special issue for his enormous contributions to cell biology using morphological approaches. Foremost in this context is his ability to use light and electron microscopy to visualize structures and processes such that the information has both scientific and artistic value. The beauty of his images helps to focus the observer more intensely on the scientific messages, which have been numerous and important. His recent studies of living cells using state-of-the-art light and video microscopy fits into a general pattern of a huge explosion in the application of these methods worldwide that is revolutionizing cell biology. However, whereas John Heuser continues to use light microscopy (LM) for a low-resolution global and dynamical overview he then moves on to the electron microscopy (EM) level to see the details; in this he is--unfortunately--in a minority; and EM is an approach that a majority of today's cell biologists never use. The continued drop in EM usage has already been articulated in recent reviews. Here, I suggest that an additional problem for EM in cell biology, in its continued crises, is the declining number of scientists who can confidently interpret the--admittedly--complex information in most electron micrographs of cells. A major re-education is needed, or cell biology as a discipline will have a real problem in the 21st century.  相似文献   

14.
Toxic solutions applied at one end of a Nitella cell 6 cm. long may produce little or no visible change in the structure of the protoplasm at the place of application but if the opposite end is covered with water its protoplasm soon disintegrates. If the middle of the cell is covered with mineral oil this region remains normal in appearance for half an hour or more. The result is due to the movement of substances in the cell. The loss of substances at the end where the toxic agent is applied results in loss at the opposite end if it is covered with water since water enters and travels along inside the cell carrying substances with it. This causes injury at the spot where the water enters. The conception developed here differs fundamentally from the usual view that the effects of injury spread gradually from the region where the toxic agent is applied to the immediately adjoining regions and thence to more remote places. The change produced by loss of substances produces an interesting pattern which deserves study.  相似文献   

15.
The behavior of the cell depends to a large extent on the permeability of the outer non-aqueous surface layer of the protoplasm. This layer is immiscible with water but may be quite permeable to it. It seems possible that a reversible increase or decrease in permeability may be due to a corresponding increase or decrease in the water content of the non-aqueous surface layer. Irreversible increase in permeability need not be due primarily to increase in the water content of the surface layer but may be caused chiefly by changes in the protoplasm on which the surface layer rests. It may include desiccation, precipitation, and other alterations. An artificial cell is described in which the outer protoplasmic surface layer is represented by a layer of guaiacol on one side of which is a solution of KOH + KCl representing the external medium and on the other side is a solution of CO2 representing the protoplasm. The K+ unites with guaiacol and diffuses across to the artificial protoplasm where its concentration becomes higher than in the external solution. The guaiacol molecule thus acts as a carrier molecule which transports K+ from the external medium across the protoplasmic surface. The outer part of the protoplasm may contain relatively few potassium ions so that the outwardly directed potential at the outer protoplasmic surface may be small but the inner part of the protoplasm may contain more potassium ions. This may happen when potassium enters in combination with carrier molecules which do not completely dissociate until they reach the vacuole. Injury and recovery from injury may be studied by measuring the movements of water into and out of the cell. Metabolism by producing CO2 and other acids may lower the pH and cause local shrinkage of the protoplasm which may lead to protoplasmic motion. Antagonism between Na+ and Ca++ appears to be due to the fact that in solutions of NaCl the surface layer takes up an excessive amount of water and this may be prevented by the addition of suitable amounts of CaCl2. In Nitella the outer non-aqueous surface layer may be rendered irreversibly permeable by sharply bending the cell without permanent damage to the inner non-aqueous surface layer surrounding the vacuole. The formation of contractile vacuoles may be imitated in non-living systems. An extract of the sperm of the marine worm Nereis which contains a highly surface-active substance can cause the egg to divide. It seems possible that this substance may affect the surface layer of the egg and cause it to take up water. A surface-active substance has been found in all the seminal fluids examined including those of trout, rooster, bull, and man. Duponol which is highly surface-active causes the protoplasm of Spirogyra to take up water and finally dissolve but it can be restored to the gel state by treatment with Lugol solution (KI + I). The transition from gel to sol and back again can be repeated many times in succession. The behavior of water in the surface layer of the protoplasm presents important problems which deserve careful examination.  相似文献   

16.
It is pointed out that there are great advantages in using single cells instead of tissues in the study of bioelectrical phenomena. Certain bioelectrical phenomena are discussed in relation to the structure of protoplasm. Under certain circumstances measurements of potential differences may enable us to determine what ions enter the protoplasm. Under suitable conditions we are able to ascertain the potential differences across the protoplasm at single points, instead of being obliged merely to measure the differences between two points.  相似文献   

17.
An aqueous solution of alizarin red S containing chloral hydrate both clears intact chlorophyllous gemma cells of Vittaria graminifolia and stains for protoplasmic calcium. Verification that the stain was protoplasmic rather than in the cell wall was shown by a positive reaction in extruded protoplasm. Similar staining was found in extruded protoplasm of Onoclea sensibilis spores. Differentiating gemma cells show localized protoplasmic accumulations of Ca2+ at sites where asymmetric cell divisions initiate the formation of rhizoids, antheridia or vegetative cells. The staining properties of the dye depend on careful control of pH and the addition of appropriate amounts of KCl to the mixture. Treatment of Onoclea spores and Vittaria gemmae with 100 mM EGTA for 30 min nearly abolishes staining of their extruded protoplasts and also of intact cells of gemmae. The use of alizarin red S with and without chloral hydrate demonstrates different pools of protoplasmic Ca2+. When Onoclea spores are ruptured to extrude the protoplasm, both dye mixtures stain a peripheral, granular protoplasmic component. However, the chloral hydrate-containing dye also reveals Ca2+ associated with small particulate protoplasmic components. Extruded protoplasm of gemma cells stains intensely with alizarin-chloral hydrate, but does not stain with alizarin lacking chloral hydrate.  相似文献   

18.
本研究以水培的烤烟给予不同浓度的Cd、Pb及其复合物处理10d后的烟叶为材料,分析了烟叶过氧化氢酶、硝酸还原酶的活性变化,测试了烟叶可溶性糖含量的变化情况,通过透射电子显微镜观察到了Cd和Pb对烟叶叶肉细胞亚显微结构的改变,特别是对叶绿体、线粒体和细胞核结构的损伤情况进行了详细观察。并探讨其毒害机理。研究结果表明:1)烟叶过氧化氢酶的活性剧烈地被Cd抑制;而随着Pb浓度的增加,其活性则表现为先增加后减弱的变化。2)Cd对硝酸还原酶活性的影响表现为先刺激增强,当Cd浓度超过50mg·L-1后,Cd剧烈地抑制其活性,当Cd浓度为200mg·L-1时,其活性几乎为零;Pb抑制烟叶硝酸还原酶的活性,仅在1000mg·L-1时出现一个低于正常活性的抗性峰。3)烟叶可溶性糖含量对Cd、Pb及其复合污染非常敏感,在较低浓度的污染处理时,其含量就明显下降,烟叶可溶性糖含量的变化可作为监测Cd、Pb污染的指标。4)Cd对烟叶叶肉细胞亚显微结构具有较强的损伤诱变作用,对细胞核、叶绿体和线粒体造成不可逆转的伤害,破坏了细胞正常生理活动所需的结构基础。电镜观察表明Cd严重地破坏细胞的膜结构。这可能是由于Cd离子与蛋白质结合而使蛋白质变性,从而使得以蛋白质为重要组成成份之一的膜的结构改变,功能丧失。5)在细胞膜的外面可以看到大量的Pb沉积粒,细胞膜可以阻止部分Pb进入原生质体内部,但在细胞质和叶绿体中仍可看到Pb沉积粒。Pb同样的损伤叶绿体、线粒体、细胞核的亚显微结构。  相似文献   

19.
In Nitella the protoplasm forms a layer about 15 microns thick surrounding a large central vacuole. The outer part of the protoplasm is a gel, the inner layer is a sol which is in continual motion travelling the entire length of the cell in opposite directions on opposite sides and thus making a complete circuit (cyclosis). If we have a cell devoid of motion and if we regard the protoplasm in any region as made up of successive portions, A, B, C, D, etc., as we pass from left to right) we may suppose that a reaction starts in B which results in a temporary loss of volume by electrostriction, so that liquid moves from A to B to fill the void thus created. The same reaction then occurs at C causing liquid to flow from B to C and so on. The protoplasmic movement can be controlled by agents which affect the viscosity of the protoplasm or the reactions which cause the flow. Certain reagents such as lead acetate stop the flow temporarily. When the motion is stopped in any region by killing or by applying lead acetate, the motion goes on for a time in adjoining regions. When motion stops in all of the cell or in certain parts, it resumes in the same direction as it had before stoppage occurred. Under normal conditions each of the two sides of the cell (on opposite sides of the white line) has its own characteristic direction of motion which remains unchanged after a temporary stoppage of motion in all parts of the cell. Hence the two sides differ and we have what may be called lateral polarity. There is also longitudinal polarity as the opposite ends of the cell are unlike since shoots grow out at one end and roots at the opposite end. The explanation suggested to account for motion in Nitella may apply to other kinds of motion including the motion of cilia and of flagella.  相似文献   

20.
This article re-contextualizes Sigmund Freud’s interest in the idea of the inheritance of acquired characteristics in terms of the socio-political connotations of Lamarckism and Darwinism in the 1930s and 1950s. Many scholars have speculated as to why Freud continued to insist on a supposedly outmoded theory of evolution in the 1930s even as he was aware that it was no longer tenable. While Freud’s initial interest in the inheritance of phylogenetic memory was not necessarily politically motivated, his refusal to abandon this theory in the 1930s must be understood in terms of wider debates, especially regarding the position of the Jewish people in Germany and Austria. Freud became uneasy about the inheritance of memory not because it was scientifically disproven, but because it had become politically charged and suspiciously regarded by the Nazis as Bolshevik and Jewish. Where Freud seemed to use the idea of inherited memory as a way of universalizing his theory beyond the individual cultural milieu of his mostly Jewish patients, such a notion of universal science itself became politically charged and identified as particularly Jewish. The vexed and speculative interpretations of Freud’s Lamarckism are situated as part of a larger post-War cultural reaction against Communism on the one hand (particularly in the 1950s when Lamarckism was associated with the failures of Lysenko), and on the other hand, against any scientific concepts of race in the wake of World War II.  相似文献   

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