LIVE STOCK-LIVER feature of our meat products. Our herds have been singularly free from disease; and the superior quality of our pork products, and their low cost compared with that of European products, gave us an immense and growing trade abroad, furnishing a wholesome and cheap meat supply to the densely populated districts of Germany and France. But this trade was almost wiped out by adverse legislation on the part of the French and German governments; in 1910 only 4,410 hogs were sent abroad as compared with 15,909 in 1901; 33,915 in 1900, and 52,230, the highest number reached, in 1899. In Great wealth has grown up with American herds, and vital interests surround them. many parts of the country dairying and animal production have driven out the growth of wheat and oats or other cereal crops, and although the population is not as dense in those regions as elsewhere, the inhabitants seem more prosperous, their houses and outbuildings are larger, and the annual profits are as great. LAZARUS N. BONHAM, Ex-Secretary State Board of Agriculture. Live Stock, Derivation of. The domestic animals of the world have all been derived from wild stock, from which they differ in a greater or less degree, according as the need and variety of their services have called for changes in the course of their development from original types. In some cases the original stock has been completely lost, so that it can only be inferred or remembered by tradition. In others it is perfectly well known from what natural species the domestic races in question have descended, and this animal may still be found in a wild state. The cattle of the world are the product mainly of three lines of descent. First, that which gave rise to the ordinary breeds known in Europe, America, and all those parts of the world that have been colonized by Europeans; second, the Indian humped cattle; and third, the varieties of the Asiatic buffalo. The last named are merely domesticated races of the existing wild buffalo of southern Asia, which are adapted to swampy lands and have been spread throughout that part of the world inhabited by Malays, and also carried to Egypt, the Senegal region and some other territories. The common cattle of the United States have come down to us apparently along two lines of descent, which are continually mingled, especially in the interior parts of the country. The cattle of New England and the eastern half of the country generally, were brought primarily, and have since been supplemented by occasional importations, from Great Britain and the Netherlands. This stock owes its origin to the domestication following the Roman conquest of western Europe, of two species of wild oxen which roamed the forests of the continent of Europe, and were found numerously there by Cæsar and his army. One of these was a longhorned kind which seems also to have been indigenous to the British Isles. The other was apparently more southerly and easterly in its distribution. Our horses are the highly varied product of the domestication of a species of horse which became entirely extinct anterior to any records. Its home, no doubt, was in the highlands of central Asia, and it was probably a small, shaggy, big-headed, dun-colored animal, more nearly resembling the Asiatic wild ass or kiang than Sheep also are of unknown origin. It is Swine are the domesticated races in Europe of the wild boar, which is still extant; and in swine that still exist there in their native state. the Orient of one or more local species of wild Poultry are more easily traced than most of the larger domesticated animals. All of our barn-yard hens and chickens, curiously diversified as they have become, are the descendants of the jungle-cock of India, still to be shot among the foot-hills of the Himalayas. Similarly the ancestry of the peafowl, guineafowl and turkeys, is found in species of birds which we still know in a wild condition. Ducks and geese are of more diverse origin, but may be geese still prevalent in many parts of Europe traced in most cases to the wild ducks and and America, or else to certain well-known species of the Orient. Liver. The liver is the largest glandular right side of the abdominal cavity immediately organ of the body. In man it is situated on the beneath the diaphragm. Its weight in the adult is approximately from 3 to 4 pounds, and it urements: greatest diameter about 12 inches size is roughly indicated by the following meas anteroposterior diameter about 7 inches, thick ness at different parts from 1 to 3 inches. The organ is divided into five lobes, of which the right and left are the principal ones; the former comprising the greatest part of the bulk of the entire organ. On the under surface may be seen a square lobe lying anteriorly between the lobe. In a similar position between the right right and left lobes, and known as the quadrate and left lobes at the posterior part of the organ is the Spigelian lobe, while a bridge-like lobe extending from the latter to the right lobe is known as the caudate lobe. The upper surface of the right and left lobes is convex and fits into the arch of the diaphragm. The lower surface of the organ is more or less concave, and is divided by five fissures. Of these a longitudinal furrow extends from the anterior to the posterior the left lobe; a transverse fissure extends at right border of the organ separating the right from angles from this at a point somewhat nearer the posterior than the anterior surface; it divides the longitudinal fissure into an umbilical fissure in front (so called on account of its lodging the umbilical vein in the foetus) and the fissure of the ing the ductus venosus in the foetus). Between ductus venosus behind (on account of its lodgthe lobus Spigelii and the right lobe of the liver is the fissure of the inferior vena cava, lodging at the side of the quadrate lobe is a fissure which that vein, while at the anterior edge of the organ accommodates the gall-bladder. The transverse fissure is the most important, as it serves for the entrance into and emergence from the organ of the blood-vessels, nerves, and hepatic ducts. The liver is held in place by five ligaments, four of which are simple folds of peritoneum, while the fifth, or ligamentum teres, is a round cord formed by the obliteration of the umbilical vein and extending from the anterior edge of the liver at the notch between the left and right lobes to the umbilicus and along the under surface of the liver to its posterior border. The peritoneal folds which serve the purpose of ligaments are a longitudinal one extending on the upper surface of the organ from the notch in front to the posterior border, a coronary ligament which is found along the posterior border, and a right and a left lateral ligament. These peritoneal reflexions serve to hold the organ in place, keeping it more or less firmly in apposition with the diaphragm. The blood-vessels entering the liver are the hepatic artery and the portal vein; the former being a branch of the coeliac axis, the latter being the large venous trunk which is formed by the union of the superior mesenteric and splenic veins. Both the hepatic artery and portal vein divide in the transverse fissure into two parts, a right and a left, which enter the substance of the right and left lobes respectively. The hepatic veins are the efferent veins of the liver conveying the blood from this organ into the inferior vena cava. In addition to these vessels, the liver, like other organs, is supplied with large and numerous lymphatics. The nervous supply of the organ is derived from the left pneumogastric, the hepatic plexus of the sympathetics, and from the right phrenic nerve. The bile ducts and hepatic ducts will be described below. The gall-bladder is a small pear-shaped sac lying on the under surface of the liver. At its narrow end it opens into a small duct (cystic duct) which passes back and down to join the hepatic duct forming the common bile duct, which terminates in the duodenum. The gallbladder is the reserve sac in which bile is stored and by the contracting of which a uniform flow of this liquid is maintained. Structure of the Hepatic Substance.— The substance of the liver is made up of lobules of more or less equal size, separated by areolar connective tissue, which is a continuation of the fibrous covering of the organ or capsule of Glisson. In these fibrous septa between the lobules are found the larger blood-vessels, biliary ducts, lymphatics, and nerves. The lobule under a low power of the microscope is seen to be composed of radiating columns of liver cells converging to a central point in which is situated a large vein (intra-lobular vein) belonging to the system of the inferior vena cava. The columns of liver cells branch and anastomose with each other, and between them are spaces occupied by blood capillaries and the primary biliary passages. The liver cells themselves are polyhedral in shape, and are so arranged that a capillary space, known as the biliary capillary, is left between them. The capillary blood-vessels are similarly formed by the peculiar juxtaposition of the liver cells, leaving spaces in which the capillary blood-vessels extend from the terminal branches of the portal vein in the septa at the periphery of the lobules to the central vein already mentioned. The latter, collecting the blood from the capillary system, transports it to larger vessels known as sublobular veins, which finally unite and form the hepatic veins and discharge the blood into the inferior vena cava. The hepatic arteries and their terminal branches occupy the septa and supply blood to the connective tissue constituting the septa, and to the walls of the portal veins and biliary ducts. The venous blood of this distribution is discharged into the terminals of the portal vein within the septa. At the periphery of the hepatic lobules, the epithelial cells of the hepatic columns continue directly into the smaller bile ducts which are situated in the interlobular septa. These primary bile ducts unite to form larger ducts and finally a right and left hepatic duct emerging from the transverse fissure unite to form a common bile duct. This is further joined by the cystic duct or duct of the gall-bladder, and it terminates in the duodenum in a common orifice with the pancreatic duct. The structure of the liver is such that the. blood entering through the portal circulation comes in contact with the liver cells on one side while the capillary biliary passages are on the other side of the hepatic cell. The lymphatic vessels accompany the portal vein and hepatic artery, and another system accompanies the branches of the hepatic vein. The capillaries penetrate into the lobules, passing between the hepatic cells. Functions of the Liver.-The physiological functions of the liver are probably very numerous and are but imperfectly understood. The position of the organ indicates that one of its important functions is the elaboration of materials presented by the blood coming from the gastro-intestinal tract, and probably also the purification of this blood. As far as they are known, the functions of the organ may be divided into the metabolic and biliary. Metabolic Functions. It is known that the liver acts upon sugars and other carbohydrate materials to convert them into glycogen which is stored up by the hepatic cells. This accumulates during digestion and is utilized in the intervals, so that the percentage of sugar in the blood is kept at an approximately uniform standard. It is known that in certain diseases (for example, diabetes), this function is greatly disturbed with resulting consequences that affect the general health. The liver shares with the muscles of the body this glycogenic function. Another important metabolic function is that of forming urea, the final stage in the metabolism of albuminous food. Uric acid also is to some extent formed in the liver but is more particularly the product of the lymphatic organs and tissues. Biliary Function. The formation of bile is one of the important attributes of the liver, though possibly this function is less predominating than has hitherto been believed. The bile is an albuminous liquid containing bile pigments (bilirubin, biliverdin), bile salts (glycocholate and taurocholate of soda), nucleo-albumin, cholesterin, fat, and other less important substances including various salts. The bile is secreted more or less intermittently, the amount being greatest about the middle part of the day and increasing after meals. The daily output is from one to two pints. Its functions are numerous. Among other properties it aids in the absorption of fatty foods, stimulates intestinal peristalsis, and prevents intestinal fermentation, and is the vehicle of excretion from the body of certain waste products, notably hemoglobin. It is known that bacteria and other minute foreign bodies are discharged from the system through this medium. DISEASES OF THE LIVER.-The diseases of the liver may be classified under the following heads: Derangements of the Circulation; Nutritional and Inflammatory Disease of the Substance of the Liver; Tumors; Parasitic Diseases; Functional Disturbance. Circulatory Disturbances.- Congestion of the Liver is an increase in the volume of blood in the organ. This may be transient or more or less permanent. (a) Transient congestion follows the ingestion of food and drink, especially when these are of stimulating quality. It is also occasioned by circulatory activity, such as accompanies fevers and other conditions of systemic excitement. In - these cases the increase of blood in the liver is the result of an excessive supply of blood to the organ. (b) Passive congestion is the form in which the outflow of blood from the liver is interfered with. This form is likely to be more or less durable or permanent. Among the causes, the most important are diseases of the heart and the lungs, or any other cause of obstruction to the circulation in the thorax. Pathological Anatomy. In active or acute congestion no marked alteration is observed on examination of the organ. In passive congestion the liver becomes enlarged, and the central veins within the lobules are seen to be increased in size, while the peripheral parts of the lobule often become light-colored from degeneration of the liver cells. This gives the surface of section of the organ a peculiar appearance that has been well designated "nutmeg liver." When passive congestion is long continued, the hepatic cells, compressed by the dilated blood-vessels and otherwise disturbed in their nutrition, undergo atrophy, while at the same time some fibrous tissue growth replaces the degenerated hepatic cells, and the whole organ becomes darker in color from deposit of pigment from the stagnated blood. The result is that the organ decreases in size, becomes harder, and of a darker color than normal. The term cyanotic or red atrophy is given to this condition. The symptoms of congestion of the liver vary with the kind, the degree, and stage of the disease. In acute congestion, such as follows overindulgence in stimulating food and drink, a sense of heaviness in the region of the liver, and perhaps slight disturbances of digestion with general malaise constitute the symptomatology. In chronic or passive congestion, such as accompanies heart disease, the symptoms are quite distinctive. The organ increases in size so much that it is easily felt in the upper part of the abdominal cavity and it becomes tender or even acutely painful. Digestive disturbances are very common, partly as the result of the condition of the liver itself and partly as the result of the underlying condition which occasioned the congestion of the liver. Among these digestive symptoms, loss of appetite, difficult and painful digestion, nausea and vomiting are the most conspicuous. When the congestion of the liver is pronounced, more or less jaundice occurs. This results from the thickening of the walls of the biliary ducts and the compression of the finer biliary channels by the swollen state of the organ. In marked cases, the jaundice may be intense; usually it is slight. In the last stages of congestion of the liver when the organ has undergone cyanotic induration, the symptoms may be similar to those of cirrhosis (q.v.). Treatment. The treatment of congestion of the liver is directed primarily toward the relief of the condition which causes the congestion. In heart diseases, cardiac tonics are important. Sometimes a prompt relief is obtained by venesection. Depletion from the portal circulation by brisk purgation may also be efficacious, and regulation of diet is important as the congested organ is less able to withstand injurious effects of stimulating foods or drink than the healthy liver. Diseases of the Substance of the Liver.— Among these may be considered: (1) Simple atrophy; (2) acute yellow atrophy; (3) fatty liver; (4) cirrhosis, and (5) abscess. Simple Atrophy of the Liver occurs in cases of starvation or inanition from long continued disease. A frequent form is that called pressure atrophy which is found in cases of deformities of the chest, in which the ribs are pressed inward against the liver, and as a result of tight lacing. The substance of the organ does not change very greatly in atrophy, though the individual liver cells are smaller than normal and usually somewhat pigmented, giving the structure a darker color. The shape of the liver is often peculiar. In the case of deformities of the chest, the pressure exerted by the ribs may cause deep grooves in the surface of the liver, or there may be a single transverse furrow at the lower margin of the ribs where this is pressed against the organ. In the case of deformity from lacing, part of the right lobe is frequently elongated and extends directly downward from the body of the organ as a more or less attenuated process. The function of the liver is probably not seriously impaired in any of these cases, though some disturbance undoubtedly occurs. Acute Yellow Atrophy is a disease in which a marked fatty degeneration of the cells of the liver is the important change. It is a rather rare condition, occurring in youth and early adult life; and has frequently been found in persons of dissipated habits. Parturition is one of the determining causes, and probably in many cases the disease is due to the action of microorganisms, or to some form of poisoning. Phosphorous poisoning may cause changes in the liver and general symptoms sometimes quite indistinguishable from those seen in acute yellow atrophy unassociated with such poisoning. The liver is decreased in size, often to a remarkable degree. It is soft and on transverse section the substance is of a light yellow color with mottled areas of reddish or purplish hue, the latter being portions in which the substance is congested or in which hemorrhages have taken place. Changes are found also in various other tissues of the body, showing that acute yellow atrophy is not wholly a disease of the liver but a general infection or intoxication, having its most marked manifestations in the liver. Symptoms.-After a period or indefinite digestive disturbances, acute jaundice, and marked nervous symptoms set in. The patient becomes deeply jaundiced, delirious, and sometimes comatose. In the course of ten days or two weeks the disease terminates fatally in a large percentage of cases. A small proportion of the cases recover. The treatment consists in stimulation or other measures called for by the general condition. Fatty Liver. There are two varieties of fatty disease of the liver, that known as infiltration and that termed fatty degeneration. In the former there is a deposition of fat in the liver cells, similar to that which is found in the subcutaneous tissues in ordinary obesity. In the latter the liver cells undergo destruction with formation of fat. Fatty infiltration may be the result of excessive supply of nutriment as in ordinary obesity, and is also found in certain states of general weakness and wasting, particularly in association with diseases of the lungs. In the latter cases, the cause is to be found in the deficient consumption of fat, owing to diminished oxygenation. Fatty degeneration may be caused by various infectious diseases, but is more particularly the result of poisoning with phosphorus, arsenic, mercury, and other poisons. In fatty infiltration, the liver is enlarged, lighter than the normal organ in specific gravity and in color, and on section with a knife the increased fat is indicated by an oily character of the cut surface. In fatty degeneration the liver usually diminished in size and the substance i of a friable softened character. There are no characteristic symptoms of farty infiltration, but the increased size of the organ may cause a local feeling of fulness and pressu, and vague disturbances of the general health may also be attributable to the condition. In fatty degeneration, the symptoms are equally obscure. That due to phosphorous poisoning may present itself with the symptoms of acute yellow atrophy (vide supra). Cirrhosis of the Liver is the most frequent and important of the diseases of this organ. It is essentially a replacement of normal liver tissue by connective tissue, causing more or less hardening. The causes of cirrhosis of the liver are numerous, though one in particular occupies a very prominent position on account of its frequency. The cause referred to is over-indulgence in alcohol, especially raw spirits, whence the terms alcoholic liver, gin drinker's liver, etc. It must not be supposed, however, that alcohol is the invariable cause. Over-eating, gouty conditions, syphilis, and various other infectious diseases may be followed by cirrhosis entirely like that caused by alcohol. It has been noted in the description of congestion of the liver that a form of cirrhosis (cyanotic induration) results from long standing congestion. Sometimes cirrhosis of a peculiar type is caused by obstruction of the biliary ducts. This produces a stagnation of the bile and an irritation of the substance of the liver that terminates in the formation of connective tissue. Pathological Anatomy.-Two forms of cirrhosis of the liver are recognized. One, known as the atrophic, in which the liver is decreased in size; the other, hypertrophic, in which the organ is increased in size. In atrophic cirrhosis (hob nail liver, granular liver), the organ has an irregular nodulated or granulated surface, the irregularities being caused by the contractions of the connective tissue which forms the basis of this pathological state of the organ. The liver is decreased in size, though not always very notably. It is very firm, and on section the increased connective tissue can be recognized in the form of more or less distinct septa interlacing the lobules or groups of lobules of the liver substance. The lobules and groups of lobules are compressed by the contracting connective tissue, and as a result undergo atrophy and degenerative change. The connective tissue formation which is characteristic of this form of cirrhosis is found in the interlobular tissues surrounding the terminal branches of the portal vein. Consequently the portal circulation is obstructed, and congestion of the various abdominal organs whose blood is discharged through this circulation results. When cirrhosis has proceeded for some time, new channels of circulation may be established, by which the congestion of the abdominal organs is relieved. There results from this visible enlargement of the veins of the abdominal walls and increased size of the veins in the lower end of the œsophagus and in the rectum. Hypertrophic cirrhosis of the liver is a form in which the liver is increased in size. The surface is usually smooth and the substance of a uniform character. This is due to the fact that the new connective tissue is uniformly distributed within as well as between the liver lobules. This form of disease may be the result of the same causes as the atrophic variety, but is more commonly due to obstructions of the flow of charge of bile is found in this form, as interferbile. Very commonly interference with the dis ence with the circulation of blood is characteristic of the other variety. the liver in earlier stages are very obscure and Symptoms.-The symptoms of cirrhosis of uncertain. Later interference with the portal circulation causes congestion of the mucous membrane of the stomach and intestines, with resulting disturbances of digestion, such as dyspepsia, vomiting, constipation, and even hemorrhages from the stomach or bowel. The spleen is enlarged from congestion of its substance and the last phase of the disease is marked by dropsical effusion in the abdominal cavity (ascites). Cirrhosis of the liver is a chronic disorder which may extend over a period of many years and which may be arrested even after it has reached an advanced stage. Among the symptoms of hypertrophic cirrhosis are tenderness and increase in the size of the liver, the development of jaundice, and sometimes the occurrence of fever. The disease is more rapid in its course than the atrophic variety. Treatment.-The treatment of this condition is preventative rather than curative. When due to alcohol it may be arrested if not too well advanced, by a control of the habit of drinking; and a restitution of normal conditions may be favored by careful diet, including mainly the avoidance of stimulating or irritating food, and of general excesses of diet. The use of saline waters may be beneficial. When advanced to the stage of dropsy of the abdominal cavity, depletive measures, such as are used for the relief of dropsies in general, may be useful; or it may be necessary to remove the liquid by tapping. |