Extracellular fluid

“ Those, which open their innumerable mouths into the cells of the whole cellular membrane; and whose use is to take up the fluid, which is poured into those cells, after it has done its office there; may be called cellular absorbents.
Those, which arise from the internal surfaces of the membranes, which line the larger cavities of the body, as the thorax, abdomen, scrotum, pericardium, take up the mucus poured into those cavities ”

“ When any secreted fluid is produced in an unusual quantity, and at the same time the power of absorption is increased in equal proportion, not only the heat of the gland becomes more intense, but the secreted fluid becomes thicker and milder, its thinner and saline parts being re-absorbed: and these are distinguishable both by their greater consistence, and by their heat, from the fluids, which are effused by the retrograde motions of the lymphatics ”

“ The tissue fluids which serve as the connecting links between the circulating blood and the individual cells are necessarily full of waste products, because these come directly from the cells to the tissue fluids and afterward pass on from them to the blood. The result is that the cells are constantly bathed in a solution of their own waste products. There is only one way in which relief from this condition can be obtained and that is by moving the used tissue fluid away bodily and letting it be replaced by fresh fluid. ”

“ Every serous membrane is moistened on its internal surface by a fluid almost the same as the serum of the blood. The exhaling orifices constantly pour it out and it is constantly taken up by the absorbents. ”

“ It is frequently impossible to obtain the proper size of field with the objectives and eye-pieces at hand. In such case, place a cardboard disc with a circular opening upon the diaphragm of the eye-piece, and adjust the size of the field by drawing out the tube. The circular opening can be cut with a cork-borer.
Diluting Fluids.—The diluting fluid should dissolve the red corpuscles so that they will not obscure the leukocytes. The simplest fluid is a 0.5 per cent. solution of acetic acid. More satisfactory is the following: glacial acetic acid, 1 c.c.; 1 per cent. ”

“ Again remove the supernatant fluid and fill in a fresh supply of saline solution and centrifugalise once more.
7. Remove the supernatant saline solution as nearly down to the level of the leucocytes as can be safely done without removing any of the leucocytes.
8. Next distribute the leucocytes evenly throughout the mass of red cells by rotating the tube between the palms of the hands—just as is done with a tube of liquefied medium prior to pouring a plate.
9. Set the tube upright in the plasticine block near to one end. ”

“ Secretions are constantly maintained, during life, from the serous membrane, by the action of the internal exhalants. The fluid which is exhaled bears some resemblance to the serum of the blood. Its use is to furnish the organs, which are surrounded by this membrane, with a proper degree of moisture, and thus enables them to move easily on each other, as those within the chest and abdomen. ”

“ But the lymph and the blood, everything considered, can hardly be looked upon as two separate and distinct liquids. Not only do they supplement each other in their work and possess striking similarities, but each is made in its movements to pass into the vessels occupied by the other, so that they are constantly mixing and mingling. For these and other reasons, they are more properly regarded as two divisions of a single liquid—one which, by adapting itself to different purposes,27 supplies all the conditions of a nutrient fluid for the cells. ”

“ The cells of the inner layer are large, and bear cilia that protrude into the internal cavity. Their functions are those of digestion and absorption. Part of the protoplasm of the outer cells is modified into a fibrous, contractile substance, which represents the beginnings of muscle tissue. The outer layer also forms a protective skin-like covering. In the outer layer also occur a large number of stinging cells, each of which has a complex mechanism for injecting a fluid poison into any creature which should happen [44] to come in contact with them. ”

“ There are no living tissues so dense that the cells of which they are composed are completely cut off from contact with body fluid. In thinking of our own bodies we should realize that this same arrangement applies; every one of our millions of living cells has contact with the fluid with which all the spaces of our bodies are filled, and it is from this fluid that the cells obtain the materials for their metabolism, and into this same fluid they discharge whatever substances their metabolism may produce. ”

“ The fact of the conveyance of fluids and other matters along the ciliated surface, as well as the direction in which they are impelled, may also be made manifest by immersing the membrane in fluid, and dropping on it some finely-pulverized substance (such as charcoal in fine powder) , which will be slowly but steadily carried along in a constant and determinate direction. ”

“ In any individual cell, for instance, it may arise from molecular asymmetry of the structure of the cell-wall, giving it greater rigidity in one direction than another, while all the while the hydrostatic pressure within the cell remains constant and uniform. In an aggregate of cells, it may very well arise from a greater chemical, or osmotic, activity in one than another, leading to a localised increase in the fluid pressure, and to a cor­re­spon­ding bulge over a certain area of the external surface. ”

“ Its outer layer « 60 » is clear or transparent, and more dense than the inner mass, which seems granular. It has at one end a curious vesicle which can be seen gradually to expand and become filled with a clear drop of liquid, and then suddenly to contract and expel the contained fluid through a series of pores in the adjacent part of the outer wall. This is the so-called pulsating vesicle, and is an organ both of circulation and excretion. In another part of the body may be seen the nucleus, which is a little cell capable, at certain times, of producing by its division new individuals. ”

“ On blood corpuscles, see ‘Quarterly Journal of Microscopical Science,’ April 1874, p. 185.’ [page 61]
under a high power, is the appearance of the finest granules in the fluid within the cells, making it slightly cloudy. These granules soon aggregate into small globular masses. I have seen a cloud of this kind appear in 10 s. after a drop of a solution of carbonate of ammonia had been given to a gland. With dark red leaves the first visible change often is the conversion of the outer layer of the fluid within the cells into bag-like masses. ”

“ Even when caused by the absorption of the carbonate or other salt of ammonia, or an infusion of meat, the process seems to be of exactly the same nature. The protoplasmic fluid must, therefore, be in a singularly unstable condition, to be acted on by such slight and varied causes. Physiologists believe that when a nerve is touched, and it transmits an influence to other parts of the nervous system, a molecular change is induced in it, though not visible to us. ”

“ We cannot argue from one substance to another; adsorptive attraction shews its effect on one and not on another; and we have not the least reason to be surprised if we find that the little granules of protoplasmic material, which as they lie bathed in the more fluid protoplasm have (presumably, and as their shape indicates) a strong surface-tension of their own, behave towards the adjacent vesicles in a very different fashion to the incipient aggregations of calcareous or siliceous matter in a colloid medium. ”

“ But when plasma of normal animals was mixed with albuminous bodies and placed in a dialysation tube, no substances giving the biuret reactions could be traced in the outer fluid, even after standing for many days. Finally, it has been proved quite recently that, by mixing the plasma or serum of specially treated animals with albumen, the nitrogenous contents of the outer fluid increase to a considerably greater extent than when the plasma of normal animals and albumen are mixed together. ”

“ But there is another kind of diffusion—osmose, or membrane diffusion. When liquids of different densities are separated by a thin membrane, diffusion takes place through this partition with a rapidity depending on the nature of the liquids and membrane, the greater flow being toward the denser fluid. The cell-wall of a root-hair is such a membrane, separating the denser liquid within the cell from the thinner one without; and, as this membrane is a living, growing one, it may be specially effective for osmotic action. ”

“ Certain conditions are essential for the continued existence of living matter. It must be surrounded by a fluid or semi-fluid medium in order that there may be easy interchange with the environment. It must constantly receive from the outside a supply of energy in the form of food, and substances formed as the result of the intracellular chemical activity must be removed. In the case of many animals it seems as though the necessity of a fluid environment for living matter did not apply, for the superficial cells of the skin have no fluid around them ”

“ All materials supplied to a tissue are brought to it by the blood, and are discharged from the blood through the capillary wall. They thus come to lie in the tissue spaces between the cells, and from this supply of material in a dissolved state the cells take up the food they require. In the opposite direction the cell discharges its waste products into this same tissue fluid. The removal of material from the tissue fluid may be effected either by its being absorbed through the capillary wall into the bloodstream, or by sending it into the lymphatic vessels and thus away from the tissue. ”

“ Hence we find that the gradual evolution of the animal kingdom goes hand in hand with the gradual development of a greater oxygen-carrying capacity of the blood and an increase in the rate of its flow.
In the groundwork of a tissue are a number of spaces—the tissue spaces. They are filled with fluid and intercommunicate freely, finally connecting with a number of fine tubes, the lymphatics, through which excess of fluid or any solid particles present are drained away. The contained fluid acts as an intermediary between the blood and the cell ”

“ Hence there is no need to suppose that an extensive accumulation of fluid and dissolved substances takes place within a tissue when it becomes active. This must be an accumulation which would lead to an engorgement of the tissue spaces and then to a discharge of fluid along the lymph channels. ”

“ Whilst undoubtedly the two functions of this circulating fluid above given are the more prominent, there are yet others of great importance. For instance, it is known that many tissues as a result of their activity produce certain chemical substances which are of essential importance to the life of other tissue cells. These substances—internal secretions as they are termed—are carried to the second tissue by the blood stream. ”

“ Transudates are non-inflammatory in origin. They contain only a few cells, and less than 2.5 per cent. of albumin, and do not coagulate spontaneously. The specific gravity is below 1018. Micro-organisms are seldom present.
Exudates are of inflammatory origin. They are richer in cells and albumin, and tend to coagulate upon standing. The specific gravity is above 1018. Bacteria are generally present, and often numerous. The amount of albumin is estimated by Esbach's method, after diluting the fluid. Bacteria are recognized by cultures, animal inoculation, or stained smears. ”

“ Raise the cover-slip in the points of the forceps and rapidly invert it on to the ring cell of the hanging-drop slide, so that the drop of fluid occupies the centre of the ring. (Carefully avoid contact between the drop of fluid and either the ring cell or the layer of vaseline. Should this happen, the now infected hanging-drop slide and its cover-slip must be dropped into the pot of lysol and a new preparation made.) ”

“ But in addition to fluid, the tissue spaces may at times be found to contain solid matter in the form of particles, which may represent the debris of destroyed cells, or which are, as is quite commonly the case, micro-organisms. Apparently such material cannot be removed from a tissue by absorption into the blood stream—indeed in the case of living organisms such an absorption would in many instances rapidly prove fatal, and special provision is made to prevent such an accident. ”

“ Should dialysing tubes be used which allow peptones to diffuse through at a variable rate, then we should be at a loss in our judgment upon the results of a test, because, as will presently be shown, a control test of the fluid to be tested must always be made, without the presence of albumen, and the results of this test be compared with those of the tests in which albumen has been mixed in the dialysing tube with the fluid under research. Should one tube be very dense and allow little or no passage at all of the peptones, we should naturally have in this a considerable source of error. ”

“ It is in the most general sense that protoplasm is “fluid.” As Graham said (of colloid matter in general) , “its softness partakes of fluidity, and enables the colloid to become a vehicle for liquid diffusion, like water itself264.” When we can deal with protoplasm in sufficient quantity we see it flow; particles move freely through it, air-bubbles and liquid droplets shew round or spherical within it; and we shall have much to say about other phenomena manifested by its own surface, which are those especially char­ac­ter­is­tic of liquids. ”