Contractile Elements

CONTRACTILE ELEMENTS, specially differentiated internal parts of protoplasm, the change in shape of which leads to movement in space, i.e., the movement of the whole organism or its parts. In their most primitive form, C. e. are described as myonemes of protozoa, e.g., many infusoria—quite thick threads, usually located in the outer layer of the body (ectoplasm) directly under the shell. During the contraction of the animal (which is very energetic in infusoria), shortening of the myonemes can be detected along with their thickening. Contractile elements reach the most perfect development for protozoa in the so-called muscular stalk of the bell animalcule (vorticella). Kolzov's research shows that the myoneme of the bell animalcule consists of a strong outer shell—the pellicle, an outer layer of protoplasm (ectoplasm), an inner homogeneous kinoplasm, and a layer of dense longitudinal fibrils at the boundary of the two parts of the plasma. Kolzov's experiments with osmotic and macerating effects on the myoneme of bell animalcules lead him to the view that the fibrils are purely supporting formations and that the active role in the process of contraction belongs to the kinoplasm. Generalizing this view, Kolzov and Roskin assume that the contractile element in a number of cases studied by them (infusoria, cells of lower and partly higher invertebrates) is liquid kinoplasm, while the dense elongated fibrils play the role of purely skeletal formations. This view, which has some data in its favor, however, meets weighty objections—a number of facts speak in favor of fibrils as the main contractile element. Further development of the myoneme type are the so-called myoepithelial cells in hydra, ascaris, and other lower vertebrates, which are also represented in a certain modification in the glands of higher vertebrates, including man; in particular, this type of formation includes the dilator pupillae muscle. The common principle of these formations is an isolated part of protoplasm with thick fibrils running through it, while the rest of the cell is represented by ordinary granular protoplasm with a nucleus, performing (e.g., in hydra) the function of glandular epithelium at times. Further complication of C. e. are the muscle cells of a number of invertebrates (leeches, ctenophores, etc.), where C. e. are located in the outer layer of cells, forming a hollow cylinder, inside which is located liquid protoplasm (sarcoplasm) with a nucleus; C. e. of the leech are represented by ribbon-like fibrils. Further development of the same principle, i.e., an increase in the amount of C. e.—myofibrils—at the expense of indifferent sarcoplasm, is encountered in the muscle cells of mollusks, as well as in the so-called smooth (intestinal) muscle cells of vertebrates. Here the sarcoplasm is reduced to a small layer around the nucleus and around the fibrils, while the whole cell is filled with myofibrils—thin threads running parallel to the longitudinal axis of the cell and possessing uniaxial birefringence. Some authors distinguish in such cells thick peripheral fibrils, to which they attribute the value of supporting ones, and bundles of thinner threads occupying a central position and being the actual C. e. The boundaries of myofibrils in smooth muscles are not accurately established; there is an opinion that they continue from one cell to another continuously, forming a kind of syncytium. The highest form of C. e. are myofibrils of striated muscles, occurring in higher invertebrates (mollusks, crustaceans, insects) and in vertebrates. The length and density of fibrils are very different even within one animal; in any case, they do not reach the end of sometimes very long fibers of striated musculature. The diameter of the myofibril of man is about 0.2 μ or slightly less. A characteristic feature of these formations is their structure. They consist of separate segments (anastomoses), separated by a thin dense partition (Z discs, Z bodies, intermediate discs); each segment consists of a section of doubly refracting dense substance (anisotropic substance, substance A) and two sections of a lighter homogeneous simply refracting substance (isotropic substance, disc I)—see Muscles, histology. The sarcoplasm located between the myofibrils, besides the function of nutrition, is attributed by some to participation in the process of muscular contraction. C. e. of muscle cells possess the basic manifestations of life—metabolism and growth, for which reason they have to be considered not as derivatives of protoplasm (metaplastic formations), but as true cell organelles. C. e. develop, as has been traced mainly for vertebrates, by multiplication, growth, fusion, and subsequent differentiation of chondriosomes. Heidenhain's view that myofibrils contain elementary submicroscopic units which are true C. e. is not shared by the majority of authors. (\ Zalkind. SOXLET APPARATUS (Soxleth) was proposed by Soxlet in 1886 (and with some later improvements in 1891) for the sterilization of milk intended for feeding small children and various milks used for feeding. The S. a. consists of a pot (water bath), into which are inserted bottles of a certain shape and capacity placed on a stand (“Soxlet bottles”). Bottles, into which a portion of food for one feeding is poured, are covered with tightly fitting rubber plates. The apparatus is placed on the fire and the water is heated to boiling. During heating of the water, vapor is released from the liquid in the bottle, displacing the air from the space located above the level of the liquid and occupying this entire space. Boiling of the water in the pot is maintained by Soxlet's instructions for 30–40 minutes. The temperature of the liquid in the bottles reaches 98–99.5° during this time. After that, the bottles are removed from the water bath and their contents are subjected to cooling, which is achieved either by cooling or by means of artificial cooling. Upon cooling, the vapors contained in the bottles in the space between the level of the liquid and the rubber ring condense and a vacuum is formed in this space; thanks to this, external air rushes into the bottle, but, meeting an obstacle to penetration into them from the side of the rubber plates, presses them and thus tightly closes the bottles. Thus, hermeticity is created, and consequently complete isolation of the contents of the bottle from external air with all the microorganisms contained in it (in Soxlet's opinion, in considerable quantity) is achieved. At the same time, due to prolonged high heating of the nutrient liquid in the bottle, the entire microbial population in it is killed, and under the influence of these two moments the liquid proves to be sterile and can maintain, in Soxlet's opinion, its sterility for a long time, up to 3–4 months. Thus, the task of Soxlet is to give every mother a device that would allow her to make the food intended for her child sterile and preserve this sterility until the moment of the child's consumption of the food. In the communication of sterility to milk, in the complete removal of microorganisms from it, Soxlet saw the solution of the entire problem of artificial feeding. In this respect, Soxlet stood infinitely far from modern views. All modern understanding of the adequacy of food and its ability to be assimilated by the child, which is the basic moment determining the successful development of the child during artificial feeding, was alien to Soxlet, and the significance of microorganisms in the etiology of diarrhea was understood by him in a crude, primitive way as direct harm to the child from the bacteria contained in his food. Similarly, the idea of the biological significance of native milk was alien to Soxlet. Based on his views, Soxlet did not stop at the requirement that milk be boiled for 40 minutes, which from a modern point of view represents a crude procedure leading to complete denaturation of milk and to the destruction or at least to a significant reduction in the vitamin content of the product. Despite the fact that some fundamental considerations laid down by Soxlet in the basis of his apparatus are refuted by modern views, the apparatus itself, as a device intended for a certain purpose, has great significance, and both the apparatus itself and the technological process of using it played the largest role in the field devoted to the processing of milk in general and in particular in the manufacture of children's food in the dairy kitchen. All devices currently used for the “sterilization” of milk, whatever their size and form, repeat the S. a. What was said by Soxlet about the fractional reheating of each portion of children's food separately and about creating the hermeticity of the stopper before the moment of the child's consumption of the children's food is now guiding in the technological practice of the dairy kitchen. Lit.: Soxlet F., Ein verbessertes Verfaliren der Milcri-Sterilisierung, Miirich. med. Wochensclirift, 1891, p. 335-353 (also separate ed.-Miinchen, 1891). Ya. Zhorno.

SOXLET APPARATUS (Soxleth) was proposed by Soxlet in 1886 (and with some later improvements in 1891) for the sterilization of milk intended for feeding small children and various milks used for feeding. The S. a. consists of a pot (water bath), into which are inserted bottles of a certain shape and capacity placed on a stand (“Soxlet bottles”). Bottles, into which a portion of food for one feeding is poured, are covered with tightly fitting rubber plates. The apparatus is placed on the fire and the water is heated to boiling. During heating of the water, vapor is released from the liquid in the bottle, displacing the air from the space located above the level of the liquid and occupying this entire space. Boiling of the water in the pot is maintained by Soxlet's instructions for 30–40 minutes. The temperature of the liquid in the bottles reaches 98–99.5° during this time. After that, the bottles are removed from the water bath and their contents are subjected to cooling, which is achieved either by cooling or by means of artificial cooling. Upon cooling, the vapors contained in the bottles in the space between the level of the liquid and the rubber ring condense and a vacuum is formed in this space; thanks to this, external air rushes into the bottle, but, meeting an obstacle to penetration into them from the side of the rubber plates, presses them and thus tightly closes the bottles. Thus, hermeticity is created, and consequently complete isolation of the contents of the bottle from external air with all the microorganisms contained in it (in Soxlet's opinion, in considerable quantity) is achieved. At the same time, due to prolonged high heating of the nutrient liquid in the bottle, the entire microbial population in it is killed, and under the influence of these two moments the liquid proves to be sterile and can maintain, in Soxlet's opinion, its sterility for a long time, up to 3–4 months. Thus, the task of Soxlet is to give every mother a device that would allow her to make the food intended for her child sterile and preserve this sterility until the moment of the child's consumption of the food. In the communication of sterility to milk, in the complete removal of microorganisms from it, Soxlet saw the solution of the entire problem of artificial feeding. In this respect, Soxlet stood infinitely far from modern views. All modern understanding of the adequacy of food and its ability to be assimilated by the child, which is the basic moment determining the successful development of the child during artificial feeding, was alien to Soxlet, and the significance of microorganisms in the etiology of diarrhea was understood by him in a crude, primitive way as direct harm to the child from the bacteria contained in his food. Similarly, the idea of the biological significance of native milk was alien to Soxlet. Based on his views, Soxlet did not stop at the requirement that milk be boiled for 40 minutes, which from a modern point of view represents a crude procedure leading to complete denaturation of milk and to the destruction or at least to a significant reduction in the vitamin content of the product. Despite the fact that some fundamental considerations laid down by Soxlet in the basis of his apparatus are refuted by modern views, the apparatus itself, as a device intended for a certain purpose, has great significance, and both the apparatus itself and the technological process of using it played the largest role in the field devoted to the processing of milk in general and in particular in the manufacture of children's food in the dairy kitchen. All devices currently used for the “sterilization” of milk, whatever their size and form, repeat the S. a. What was said by Soxlet about the fractional reheating of each portion of children's food separately and about creating the hermeticity of the stopper before the moment of the child's consumption of the children's food is now guiding in the technological practice of the dairy kitchen. Lit.: Soxlet F., Ein verbessertes Verfaliren der Milcri-Sterilisierung, Miirich. med. Wochensclirift, 1891, p. 335-353 (also separate ed.-Miinchen, 1891). Ya. Zhorno.

SOXLET APPARATUS (Soxleth) was proposed by Soxlet in 1886 (and with some later improvements in 1891) for the sterilization of milk intended for feeding small children and various milks used for feeding. The S. a. consists of a pot (water bath), into which are inserted bottles of a certain shape and capacity placed on a stand (“Soxlet bottles”). Bottles, into which a portion of food for one feeding is poured, are covered with tightly fitting rubber plates. The apparatus is placed on the fire and the water is heated to boiling. During heating of the water, vapor is released from the liquid in the bottle, displacing the air from the space located above the level of the liquid and occupying this entire space. Boiling of the water in the pot is maintained by Soxlet's instructions for 30–40 minutes. The temperature of the liquid in the bottles reaches 98–99.5° during this time. After that, the bottles are removed from the water bath and their contents are subjected to cooling, which is achieved either by cooling or by means of artificial cooling. Upon cooling, the vapors contained in the bottles in the space between the level of the liquid and the rubber ring condense and a vacuum is formed in this space; thanks to this, external air rushes into the bottle, but, meeting an obstacle to penetration into them from the side of the rubber plates, presses them and thus tightly closes the bottles. Thus, hermeticity is created, and consequently complete isolation of the contents of the bottle from external air with all the microorganisms contained in it (in Soxlet's opinion, in considerable quantity) is achieved. At the same time, due to prolonged high heating of the nutrient liquid in the bottle, the entire microbial population in it is killed, and under the influence of these two moments the liquid proves to be sterile and can maintain, in Soxlet's opinion, its sterility for a long time, up to 3–4 months. Thus, the task of Soxlet is to give every mother a device that would allow her to make the food intended for her child sterile and preserve this sterility until the moment of the child's consumption of the food. In the communication of sterility to milk, in the complete removal of microorganisms from it, Soxlet saw the solution of the entire problem of artificial feeding. In this respect, Soxlet stood infinitely far from modern views. All modern understanding of the adequacy of food and its ability to be assimilated by the child, which is the basic moment determining the successful development of the child during artificial feeding, was alien to Soxlet, and the significance of microorganisms in the etiology of diarrhea was understood by him in a crude, primitive way as direct harm to the child from the bacteria contained in his food. Similarly, the idea of the biological significance of native milk was alien to Soxlet. Based on his views, Soxlet did not stop at the requirement that milk be boiled for 40 minutes, which from a modern point of view represents a crude procedure leading to complete denaturation of milk and to the destruction or at least to a significant reduction in the vitamin content of the product. Despite the fact that some fundamental considerations laid down by Soxlet in the basis of his apparatus are refuted by modern views, the apparatus itself, as a device intended for a certain purpose, has great significance, and both the apparatus itself and the technological process of using it played the largest role in the field devoted to the processing of milk in general and in particular in the manufacture of children's food in the dairy kitchen. All devices currently used for the “sterilization” of milk, whatever their size and form, repeat the S. a. What was said by Soxlet about the fractional reheating of each portion of children's food separately and about creating the hermeticity of the stopper before the moment of the child's consumption of the children's food is now guiding in the technological practice of the dairy kitchen. Lit.: Soxlet F., Ein verbessertes Verfaliren der Milcri-Sterilisierung, Miirich. med. Wochensclirift, 1891, p. 335-353 (also separate ed.-Miinchen, 1891). Ya. Zhorno.

SOXLET APPARATUS (Soxleth) was proposed by Soxlet in 1886 (and with some later improvements in 1891) for the sterilization of milk intended for feeding small children and various milks used for feeding. The S. a. consists of a pot (water bath), into which are inserted bottles of a certain shape and capacity placed on a stand (“Soxlet bottles”). Bottles, into which a portion of food for one feeding is poured, are covered with tightly fitting rubber plates. The apparatus is placed on the fire and the water is heated to boiling. During heating of the water, vapor is released from the liquid in the bottle, displacing the air from the space located above the level of the liquid and occupying this entire space. Boiling of the water in the pot is maintained by Soxlet's instructions for 30–40 minutes. The temperature of the liquid in the bottles reaches 98–99.5° during this time. After that, the bottles are removed from the water bath and their contents are subjected to cooling, which is achieved either by cooling or by means of artificial cooling. Upon cooling, the vapors contained in the bottles in the space between the level of the liquid and the rubber ring condense and a vacuum is formed in this space; thanks to this, external air rushes into the bottle, but, meeting an obstacle to penetration into them from the side of the rubber plates, presses them and thus tightly closes the bottles. Thus, hermeticity is created, and consequently complete isolation of the contents of the bottle from external air with all the microorganisms contained in it (in Soxlet's opinion, in considerable quantity) is achieved. At the same time, due to prolonged high heating of the nutrient liquid in the bottle, the entire microbial population in it is killed, and under the influence of these two moments the liquid proves to be sterile and can maintain, in Soxlet's opinion, its sterility for a long time, up to 3–4 months. Thus, the task of Soxlet is to give every mother a device that would allow her to make the food intended for her child sterile and preserve this sterility until the moment of the child's consumption of the food. In the communication of sterility to milk, in the complete removal of microorganisms from it, Soxlet saw the solution of the entire problem of artificial feeding. In this respect, Soxlet stood infinitely far from modern views. All modern understanding of the adequacy of food and its ability to be assimilated by the child, which is the basic moment determining the successful development of the child during artificial feeding, was alien to Soxlet, and the significance of microorganisms in the etiology of diarrhea was understood by him in a crude, primitive way as direct harm to the child from the bacteria contained in his food. Similarly, the idea of the biological significance of native milk was alien to Soxlet. Based on his views, Soxlet did not stop at the requirement that milk be boiled for 40 minutes, which from a modern point of view represents a crude procedure leading to complete denaturation of milk and to the destruction or at least to a significant reduction in the vitamin content of the product. Despite the fact that some fundamental considerations laid down by Soxlet in the basis of his apparatus are refuted by modern views, the apparatus itself, as a device intended for a certain purpose, has great significance, and both the apparatus itself and the technological process of using it played the largest role in the field devoted to the processing of milk in general and in particular in the manufacture of children's food in the dairy kitchen. All devices currently used for the “sterilization” of milk, whatever their size and form, repeat the S. a. What was said by Soxlet about the fractional reheating of each portion of children's food separately and about creating the hermeticity of the stopper before the moment of the child's consumption of the children's food is now guiding in the technological practice of the dairy kitchen. Lit.: Soxlet F., Ein verbessertes Verfaliren der Milcri-Sterilisierung, Miirich. med. Wochensclirift, 1891, p. 335-353 (also separate ed.-Miinchen, 1891). Ya. Zhorno.