Excretory organ

“ The details of the structure and development of the sense-organs, gill-slits and visceral organs of Craniates are sufficiently discussed in the articles dealing with the separate classes of the group. It is necessary to refer, however, to new light thrown on the structure and morphology of the renal excretory organs due chiefly to the investigations of Goodrich. The excretory organs of the vast majority of invertebrate coelomate animals are essentially what are known as nephridia. ”

“ They have a cuticular epithelium (fig. 129) entirely or partly covered with cilia, beneath this a dermo-muscular tube composed of circular and longitudinal muscles; also, a simple gut sac with an œsophagus, occasionally also with pharynx, salivary glands and boring spine, also a cerebral ganglion on which, in some species, there are eyes (fig. 131, a) . As to the excretory organs, they are represented by two symmetrically placed terminal flame cells, with excretory vessels opening separately; there is a more or less ample (primary) body cavity between the parietes of the body and the gut ”

“ First, other congeries of glands occupy but a particular part of the system, or constitute a particular organ, as the liver, or kidneys; but those glands, which secrete the mucus, and perspirable matter, which are called capillaries, are of very great extent; they receive the blood from the arteries, separate from it the mucus, which lines every cell, and covers every cavity of body; and the perspirable matter, which softens and lubricates the whole surface of the skin, and the more extensive surface of the air-vessels, which compose the lungs. ”

“ From all that I have said, it is evident that in the organs whose capillary system contains in part blood, and in part different fluids, the proportion of the first to the others is infinitely variable; that a thousand causes in a state of health, as in that of disease, by bringing to the organ more or less blood, can fill more or less its capillary system. ”

“ The general character of tertiary manifestations may be stated as follows: They attack by preference the tissues derived from the mesoblastic layer of the embryo—the cellular tissue, bones, muscles, and viscera. They are often localised to one particular tissue or organ, such, for example, as the subcutaneous cellular tissue, the bones, or the liver, and they are rarely symmetrical. They are usually aggressive and persistent, with little tendency to natural cure, and they may be dangerous to life, because of the destructive changes produced in such organs as the brain or the larynx. ”

“ Their most intimate sympathy must be with the organs of circulation, with the lung, liver, intestine, and skin. As the skin is also an organ of evaporation, so is the antagonism between it and the kidneys of a direct or immediate kind. The skin is the kidneys expanded into a large cyst. These are in turn, just as the lung is, the inverted skin.
2944. A lung in the reversed animal can do nothing else but expire. It only expels the evaporated matter of the sanguinary system, but takes in none, so as to alter or support the blood. The sexual animal aims at the destruction of the animal. ”

“ The last named is oval and formed of four rows of large cells; it is separated by a sphincter from the rectum, which opens posteriorly and dorsally. The nitrogenous excretory apparatus consists of a coiled tube on each side of the stomach; internally the tubes end in large flame-cells, and externally by small pores which lie on the edges of the ventral row of scales. A cerebral ganglion rests on the oesophagus and supplies the cephalic cilia and hairs; it is continued some way back as two dorsal nerve trunks. The sense organs are the hairs and bristles and in some species eyes. ”

“ This newly-developed connective tissue gradually contracts, and in so doing crushes the cells and obstructs the blood-vessels, making the organ much smaller than natural, and causing the surface to be covered with little projecting knobs, consisting of portions of liver-tissue that have been less compressed than the part that separates them. ”

“ In the examination of the body-cavities and hollow organs, as well as pathologic hollow structures, the first thing to note is the escape of gas or air under pressure. Occasionally it is best to open the organ under water to note the escape of bubbles. The odor of the gas, inflammability, etc., are to be noted. The fluid or solid contents (blood, bile, urine, féces, mucus, pus, exudates and transudates, altered secretions, food-remains, concretions, foreign bodies, parasites, etc.) ”

“ In the same way the kidneys can also be kept in good condition if too much meat be not taken. These eliminate the end-products of meat food, and the more of such products that pass through the kidneys, the more of them are taken from the blood and excreted by means of the fine epithelia of the kidney tubules, and thus the more is the work done by these organs; and we have mentioned that any overwork of an organ may be followed by its exhaustion. ”

“ Secretion takes place, e. g. of bile and saliva, in so far as the processes of the body, especially those of the digestion, are promoted. Excretion is only effected in so far as that the organs, into which what is secreted enters, may obtain a tracheal signification, i. e. evaporation. All404 excretory orifices are in a certain sense larynges or tracheal orifices. Thus, this relation between secretion and excretion would have been discovered without recourse to conjecture being had upon our part. ”

“ The blood contains the materials of all the secretions, of the nutrition of all the organs, and of all the exhalations. Each gland draws from this common reservoir what is necessary to its secretion, as each organ does what is proper for its nutrition, and as each serous surface does what is suitable for its exhalation. Now it is by its organic sensibility that each living part of the body distinguishes what its functions require. ”

“ When the pores are obstructed, and transpiration is checked, the elements of the transpired fluids will necessarily be retained in the system; and, as they are injurious and poisonous if retained, they must be removed by those organs whose functions in the animal economy are similar, as the lungs, kidneys, liver, intestines, &c.
687. When these organs are called upon to perform their offices, and in addition that of another, the healthy equilibrium is destroyed, and the oppressed organ will suffer from exhaustion, and become the prey of disease. ”

“ It is nothing more than a regulator; than an organ for directing the blood in a determinate course in order that this may not wholly stagnate, or only be the plaything of a force acting in another way, as, for example, through that afforded by the body-cavity and the inner digestive canal. At regular intervals a portion of the blood is sucked through the same, and then by means of the anterior supply tube it is pushed onward into the head, whence it passes into the cavities of the tissues. ”

“ These organs are,—the lungs, which throw off a portion of useless matter when the blood is purified; the kidneys, which secrete liquids that pass into the bladder, and are thrown out from the body by that organ; and the intestines, which carry off the useless and more solid parts of the food, after the lacteals have drawn off the chyle. In addition to these organs, the skin has a similar duty to perform; and as it has [Pg 92] so much larger a supply of blood, it is the chief organ in relieving the body of the useless and noxious parts of the materials which are taken for food. ”

“ In the kidney, the substances secreted by the cells, being of no farther use, are at once ejected from the body. Hence the renal tissue may be spoken of as excretory. In the epithelium cells of the lungs, the protoplasm plays an altogether subordinate part in the assumption of oxygen and the excretion of carbonic acid. ”

“ On the other hand, if the lungs cannot oxidize the blood, or the heart drive fresh pabulum to the brain, that organ collapses immediately, and, if a stream of [104] pure blood is not quickly restored to it, dies. No return of the circulation can then restore it; the death of the rest of the animal must follow.
Being the most delicate, the cells of the central nervous system usually die first, and we then say that the man is dead. So the body may be, but much of the protoplasm of which it is composed—whole organs, in fact—remains alive ”

“ The appearances left in the body are increased density and firmness of the whole brain or a part of it,—flattening of the convolutions on their outer surface, so that their grooves are almost obliterated and the investing membrane uncommonly dry,—unusual emptiness of the blood-vessels of the brain and its membranes,—and a protrusion of the brain upwards on removal of the skull-cap, as if the organ were too large for its containing cavity. ”

“ When a worker occupies himself with the effect of the extirpation of one organ of digestion upon the organs in the next segment of the digestive apparatus, he naturally thinks of phenomena of exclusion or loss of function in one or the other of the segments following the one extirpated, but instead of phenomena of exclusion it is conceivable that those of exaggerated activity in the other segments of the digestive tube might result. ”

“ The removal of these glands in animals produces a condition resembling acute poisoning accompanied by spasmodic contraction of the muscles. A small glandular organ at the base of the brain, the pituitary body, produces a secretion, one of the most marked properties of which is a control of growth, particularly that of the bones. Most cases of giantism, combined as they are with imperfect mentality, are due to disease of this gland. There are glands near the kidney which regulate the pressure of the blood in the arteries by causing contraction of their muscular walls. ”

“ The body-wall is highly muscular and, except in a few probably specialized cases, possesses chitinous spines, the setae, which are secreted by the ectoderm and are embedded in pits of the skin. They possess a modified anterior end, frequently with special sense organs, forming a head, a segmented nervous system, consisting of a pair of anterior, dorsally-placed ganglia, a ring surrounding the alimentary canal, and a double ventral ganglionated chain, a definite vascular system, an excretory system consisting of nephridia, and paired generative organs formed from the coelomic epithelium. ”

“ II. The irritative diseases of the kidneys, pancreas, spleen, and other glands, are analogous to those of the liver above described, differing only in the consequences attending their inability to action. For instance, when the secretory vessels of the kidneys become disobedient to the stimulus of the passing current of blood, no urine is separated or produced by them; their excretory mouths become filled with concreted mucus, or calculus matter, and in eight or ten days stupor and death supervenes in consequence of the retention of the feculent part of the blood. ”

“ Thus an excavation is sometimes found in the liver or spleen; or the diaphragm is pierced through and through. The margins of the latter holes are without any sign of vascular action, but are generally besmeared with a dark pulpy mass, the remains of the softened tissue. The pulp never smells of gangrene; with which, indeed, this species of softening is wholly unconnected. The edge of the hole in the stomach never adheres to the adjoining organ; yet, even when the hole is very large, the contents of the stomach have not always made their escape. ”

“ The excretory system of kidneys and similar structures collects the ash-waste produced by the burning tissues, and discharges this from the whole mechanism, like the ash hoist of a steamship. The circulatory system, made up of smaller and larger vessels, with or without a heart, transports and propels the blood through the body, carrying the absorbed foods, the supplies of oxygen, and the waste substances of various kinds. All of these four systems are concerned with "commissary" problems, so to speak, which every individual must solve for and by itself. ”

“ In opening the various organs an incision should be made which will expose the greatest amount of surface at one cut. Never make a number of small and always unsatisfactory incisions in an organ. In opening certain organs like the brain and heart, the incisions are so planned that the parts of the organ may be folded together, and, if necessary, their relations to one another and the whole organ studied. ”

“ But each of these organs also eliminates those products which are eliminated by the other two. Thus the lungs, whilst they get rid principally of carbon dioxide, also get rid of water in the form of steam and of nitrogenous matter. The skin gives off a certain quantity of carbon dioxide and nitrogen excreta. And the renal organs also eliminate all three of the chief forms of excretory matter. When any one of these three organs is not functioning at its best, extra work is thrown upon the others, and in some extreme cases this metastasis, or transference of function, is very remarkable. ”

“ On the contrary, the simple organization of the exhalant surfaces, which have only vessels continuous with the arteries, and without an intermediate organ, requires much less for them to grow preternaturally in parts, in which they were before unknown. ”

“ Through this faculty of the lining tissue of the blood-vessels, the size of the lumen and the direction of branching are so regulated as to oppose the least possible resistance to the flow of the blood.
" (2) The faculty possessed by the endothelium of the capillaries of each organ of adapting itself qualitatively to the particular metabolism of the organ." This adaptedness of the capillaries is, however, more usually an inherited state, i.e., brought about in the first period of development. ”