Part 5

The fourth division of the stomach of the ox is called _abomasum_. It somewhat resembles the duodenum of the horse in its function, it being the true digestive stomach. It is studded with numerous nerves, blood-vessels, and small glands. It is a laboratory admirably fitted up by the Divine Artist, and is capable of carrying on the chemico-vital process as long as the animal lives, provided its healthy functions are not impaired. The glands alluded to secrete from the blood a powerful solvent, called the _gastric juice_, which is the agent in reducing the food to chyme and chyle. This, however, is accomplished by the united agency of the bile and pancreatic juice. Both these fluids are conveyed into the abomasum by means of small tubes or canals. Secretions also take place from the inner membrane of the intestines, and, as the result of the united action of all these fluids, aided by the muscular motion just alluded to, which is also communicated to the intestines, a substance is formed called _chyle_, which is the most nutritious portion of the food, and has a milky appearance. The chyle is received into a set of very minute tubes, called _lacteals_, which are exceedingly numerous, and arise by open mouths from the inner surface of the abomasum and intestines. They receive the chyle; from thence it passes into a receptacle, and finally into the thoracic duct. The thoracic duct opens into a vein leading directly to the heart; so that whatever portion of the chyle is not actually needed by the organism is thoroughly mixed with the general mass of blood. That portion of chyme which is not needed, or cannot be converted into chyle, descends into the intestines, and is finally carried out of the body by the rectum.

The manner in which the gastric fluids act on alimentary matter, is by solution and chemical action; for cornstalks and foxgrass, that cannot be dissolved by ammonia or alcohol, yield readily to the solvent power of the gastric secretion. Bones and other hard substances are reduced to a pulpy mass in the stomach of a dog; while, at the same time, many bodies of delicate texture remain in the stomach, and ultimately are ejected, without being affected by the gastric fluids. This different action on different subjects is analogous to the operation of chemical affinity, and corroborates the theory that digestion is effected by solution and chemical action.

_The Spleen_, or _Milt_, is an oblong, dark-colored substance, having attachments to the paunch. It is composed of blood-vessels, nerves, and lymphatics, united by cellular structure. It appears to serve as a reservoir for the blood that may be designed for the secretions of bile in the liver. P. M. Roget says, "Any theory that assigns a very important function to the spleen will be overturned by the fact, that in many animals the removal of this organ, far from being fatal, or interrupting, in any sensible manner, the continuance of the functions, seems to be borne with perfect impunity." Sir E. Home, Bichat, Leuret, Lassaigne, and others, suppose that "the spleen serves as a receptacle for the superfluous quantity of fluid taken into the stomach."

_The Liver_ is a dense gland, of a lobulated structure, situated below the diaphragm, or "skirt." It is supplied, like other organs, with arterial blood, by vessels, called _hepatic_ arteries, which are sent off from the great aorta. It receives also a large amount of venous blood, which is distributed through its substance by a separate set of vessels, derived from the venous system. The veins which receive the blood that has circulated in the usual manner unite together into a large trunk, called vena portæ, (gate vein,) and this vein, on entering the liver, ramifies like an artery, and ultimately terminates in the branches of the hepatic veins, which transmit the blood, in the ordinary course of circulation, to the vena cava, (hollow vein.) Mr. Kiernan says, "The hepatic veins, together with the lobules which surround them, resemble, in their arrangement, the branches and leaves of a tree, the substance of the lobules being disposed around the minute branches of the veins like the parenchyma of a leaf around its fibres. The hepatic veins may be divided into two classes, namely, those contained in lobules, and those contained in canals formed by lobules. The first class is composed of interlobular branches, one of which occupies the centre of each lobule, and receives the blood from a plexus formed in the lobule by the portal vein; and the second class of hepatic veins is composed of all those vessels contained in canals formed by the lobules, and including numerous small branches, as well as the large trunks terminating in the inferior cava. The external surface of every lobule is covered by an expansion of '_Glisson's capsule_,' by which it is connected to, as well as separated from, contiguous lobules, and in which branches of the hepatic duct, portal veins, and hepatic artery ramify. The ultimate branches of the hepatic artery terminate in the branches of the portal vein, where the blood they respectively contain is mixed together, and from which mixed blood the bile is secreted by the lobules, and conveyed away by the hepatic ducts. The remaining blood is returned to the heart by the hepatic veins, the beginnings of which occupy the centre of each lobule, and, when collected into trunks, pour their contents into the inferior cava. Hence the blood which has circulated through the liver, and has thereby lost its arterial character, is, in common with that which is returning from other parts, poured into the vena portæ, and contributes its share in furnishing materials for the biliary secretion. The hepatic artery furnishes nutrition to the liver itself."

The bile, having been secreted, accumulates in the gall-bladder, where it is kept for future use. When the healthy action of the fourth stomach is interrupted, the bile is supposed to be reabsorbed,--it enters into the different tissues, producing yellowness of the eyes; the malady is then termed _yellows_, _jaundice_, &c. Sometimes the passage of the bile is obstructed by calculi, or gall-stones; they have been found in great numbers in oxen.

_The Pancreas_ is composed of a number of lobules or glands; a small duct proceeds from each; they unite and form a common canal, which proceeds towards, and terminates in, the fourth stomach. The pancreatic juice appears to be exceedingly analogous, both in its sensible properties and chemical composition, to the saliva.

"The recent researches of MM. Bouchardat, Sandras, Mialhe, Bareswil, and Bernard himself, have placed beyond a doubt the existence of a ferment, in some of the fluids which mix with the alimentary mass, destined to convert starchy matters into sugar. They have proved that the gastric juice has for its peculiar office the solution and digestion of azotized substances. There remained to be ascertained the real agent for the digestion of fatty matters; that is to say, the agent in the formation of chyle out of those substances.

"M. Bernard has proved that this remarkable office is performed by the pancreatic juice; he has demonstrated the fact by three conclusive proofs.

"1. The pancreatic juice, pure and recently formed, forms an emulsion with oils and fats with the greatest facility. This emulsion may be preserved for a long time, and the fatty substance soon undergoes a fermentation which separates its constituent acids.

"2. The chyle only begins to appear in the lacteals below that part of the intestinal tube where the pancreatic juice enters it to mix with the alimentary matters.

"3. In disorders of the pancreas, we find that the fatty matters, contained in the food, pass entire in the evacuations."

The above is an extract from the report of a body composed of several members of the French Academy of Sciences. "M. Bernard" (continues the report) "has exhibited to us the first of these experiments, and has furnished us with the means of repeating it with the several varieties of the gastric juice. We have not the slightest doubt on the subject. It is incontestable that fatty substances are converted into an emulsion by this juice, in a manner easy and persistent, and it is no less true that the saliva, the gastric juice, and the bile are destitute of this property.

"The second demonstration can be given in various modes; but the author has discovered, in the peculiar arrangement of the digestive apparatus of the rabbit, an unexceptional means of obtaining it with the greatest precision, and at will. The pancreatic juice enters the intestinal tube of this animal about fourteen inches below the point where the bile is poured in. Now, as long as the food is above the region where it mixes with the pancreatic juice, there appears to be no formation and separation of a milky chyle; nothing shows that the fatty matters are reduced to an emulsion. On the contrary, as soon as the pancreatic juice mixes with the alimentary matters, we observe the fat to be converted into an emulsion, and a milky chyle to fill the corresponding lacteals. Nothing can give an idea of the result of these experiments, which have all the accuracy of a chemical operation performed in the laboratory, and all the beauty of the most perfect injection.

"We are not, therefore, surprised that divers pathological cases, hitherto imperfectly understood, should come to confirm the views of M. Bernard, by proving that, in diseases of the pancreas, fatty matters have been observed to pass unchanged in the dejections.

"The committee cannot hesitate to conclude that the author has perfectly demonstrated his physiological propositions; that he has completed the general characters of the theory of digestion, and that he has made known the mode of formation of the fatty matter of the chyle, and the manner of the digestion of the fatty matters."

_The Kidneys._--Their office is, to secrete from the blood the useless or excrementitious fluids in the form of urine. When the skin is obstructed, the secretion is augmented, and profuse perspiration lessens it. From a cavity in the centre of each kidney a canal or tube proceeds, by which the urine is conveyed into the bladder. These tubes are named _ureters_. As the ureters enter the bladder, they pass forward, a short distance between its coats; which effectually prevents the urine from taking a retrograde course. The urine is expelled by the muscular power which the bladder possesses of contracting upon its contents.

RESPIRATION AND STRUCTURE OF THE LUNGS.

The organs of respiration are the larynx, the trachea, or windpipe, bronchia, and the lungs.

The air is expelled from the lungs principally by the action of the muscles of respiration; and when these relax, the lungs expand by virtue of their own elasticity. This may be exemplified by means of a sponge, which may be compressed into a small compass by the hand, but, upon opening the hand, the sponge returns to its natural size, and all its cavities become filled with air. The purification of the blood in the lungs is of vital importance, and indispensably necessary to the due performance of all the functions; for if they be in a diseased state,--either tuberculous, or having adhesions to the pleura, their function will be impaired; the blood will appear black; loaded with carbon; and the phlebotomizer will have the very best (worst) excuse for taking away a few quarts with a view of purifying the remainder! The trachea, or windpipe, after dividing into smaller branches, called _bronchia_, again subdivides into innumerable other branches, the extremities of which are composed of an infinite number of small cells, which, with the ramifications of veins, arteries, nerves, and connecting membranes, make up the whole mass or substance of the lungs. The internal surface of the windpipe, bronchia, and air-cells, is lined with a delicate membrane, highly organized with blood-vessels, &c. The whole is invested with a thin, transparent membrane--a continuation of that lining the chest, named _pleura_. It also covers the diaphragm, and, by a duplication of its folds, forms a separation between the lobes of the lungs.

CIRCULATION OF THE BLOOD.

The blood contains the elements for building up, supplying the waste of, and nourishing the whole animal economy. On making an examination of the blood with a microscope, it is found full of little red globules, which vary in their size and shape in different animals, and are more numerous in the warm than in the cold-blooded. Probably this arises from the fact that the latter absorb less oxygen than the former. When blood stands for a time after being drawn, it separates into two parts. One is called _serum_, and resembles the white of an egg; the other is the clot, or crassamentum, and forms the red coagulum, or jelly-like substance. This is accompanied by whitish tough threads, called _fibrine_.

When blood has been drawn from an animal, and it assumes a cupped or hollow form, if serum, or buffy coat, remains on its surface, it denotes an impoverished state; but if the whole, when coagulated, be of one uniform mass, it indicates a healthy state of that fluid. The blood of a young animal, provided it be in health, coagulates into a firm mass, while that of an old or debilitated one is generally less dense, and more easily separated. The power that propels the blood through the different blood-vessels is a mechanico-vital power, and is accomplished through the involuntary contractions and relaxations of the heart; from certain parts of which arteries arise, in other parts veins terminate. (See Plate.)

The heart is invested with a strong membranous sac, called _pericardium_, which adheres to the tendinous centre of the diaphragm, and to the great vessels at its superior portion. The heart is lubricated by a serous fluid, secreted within the pericardium, for the purpose of guarding against friction. When an excess of fluid accumulates within the sac, it is termed dropsy of the heart. The heart is divided into four cavities, viz., two auricles, named from their resemblance to an ear, and two ventricles, (as seen at _a_, _b_,) forming the body. The left ventricle is smaller than the right, yet its walls are much thicker and stronger than those of the latter: it is from this part that the large trunk of the arteries proceed, called the _great aorta_. The right cavity, or ventricle, is the receptacle for blood returned by the venous structure after having gone the rounds of the circulation; the veins terminating, as they approach the heart, in a single vessel, called _vena cava_, (see plate, _o_, _q_, ascending and descending portion.) The auricle on the left side of the heart receives the blood that has been distributed through the lungs for purification. Where the veins terminate in auricles, there are valves placed, to prevent the blood from returning. For example, the blood proceeds out of the heart along the aorta; the valve opens upwards; the blood also moves upwards, and raises the valve, and passes through; the pressure from above effectually closes the passage. The valves of the heart are composed of elastic cartilage, which admits of free motion. They sometimes, however, become ossified. The heart and its appendages are, like other parts of the system, subject to various diseases, which are frequently very little understood, yet often fatal. Now, the blood, having passed through the veins and vena cava, flows into the right auricle; and this, when distended, contracts, and forces its contents into the right ventricle, which, contracting in its turn, propels the blood into the pulmonary arteries, whose numerous ramifications bring it in contact with the air-cells of the lungs. It then, being deprived of its carbon, assumes a crimson color. Having passed through its proper vessels, it accumulates in the left auricle. This also contracts, and forces the blood through a valve into the left ventricle. This ventricle then contracts in its turn, and the blood passes through another valve into the great aorta, to go the round of the circulation and return in the manner just described.

Many interesting experiments have been made to estimate the quantity of blood in an animal. "The weight of a dog," says Mr. Percival, "being ascertained to be seventy-nine pounds, a puncture was made with the lancet into the jugular vein, from which the blood was collected. The vein having ceased to bleed, the carotid artery of the same side was divided, but no blood came from it; in a few seconds afterwards, the animal was dead. The weight of the carcass was now found to be seventy-three and a half pounds; consequently it had sustained a loss of five and a half pounds--precisely the measure of the blood drawn. It appears from this experiment, that an animal will lose about one fifteenth part of its weight of blood before it dies; though a less quantity may so far debilitate the vital powers, as to be, though less suddenly, equally fatal. In the human subject, the quantity of blood has been computed at about one eighth part of the weight of the body; and as such an opinion has been broached from the results of experiments on quadrupeds, we may fairly take that to be about the proportion of it in the horse; so that if we estimate the weight of a horse to be thirteen hundred and forty-four pounds, the whole quantity of blood will amount to eighty-four quarts, or one hundred and sixty-eight pounds; of which about forty-five quarts, or ninety pounds, will commonly flow from the jugular vein prior to death; though the loss of a much less quantity will deprive the animal of life."

REMARKS ON BLOOD-LETTING.

The author has been, for several years, engaged in a warfare against the use of the lancet in the treatment of the various diseases of animals. When this warfare was first commenced, the prospect was poor indeed. The lancet was the great anti-phlogistic of the allopathic school; it had powerful, talented, and uncompromising advocates, who had been accustomed to resort to it on all occasions, from the early settlement of America up to that period. The great mass had followed in the footsteps of their predecessors, supposing them to be infallible. Men and animals were bled; rivers of blood have been drawn from their systems; yet they often got well, and men looked upon the lancet as one of the blessings of the age, when, in fact, it is the greatest curse that ever afflicted this country: it has produced greater losses to owners of domestic animals than did ever pestilence or disease. A few philanthropic practitioners have, from time to time, in other countries, as well as in this, labored during their life, and on their death-bed, to convince the world of the destructive tendency of blood-letting in human practice; but none that we know of ever had the moral courage to wage a general warfare against the practice in the veterinary department, until we commenced it. We have met with great success, and have given the blood-letting gentry who practise it at the present day ("just to please their employers or to make out a case") a partial quietus: in a few more years, unless they abandon their false theories, their occupation, notwithstanding their pretensions to cure _secundum artem_, will, like Othello's, be "gone." But we are not writing for doctors. Our business is with the farmers--the lords of creation. The former are mere lords of pukes and purges; they, like the farmers, have the materials, however, to mould themselves into men of common sense; but the fact is, they are hide-bound; they want a national sweat, to rid their systems, especially their upper works, of the theories of Sydenham and Paracelsus, which have shipwrecked many thousands of the medical profession. They shut their eyes to the results of medical reform, and cling, with all their soul, and with all their might, worthy a better cause, to a system that "always was false."

Lord Byron, like many other learned men, was well acquainted with the impotency of the healing art, and held the lancet in utter abhorrence: when beset, day and night, to be bled, the bard, in an angry tone, exclaimed, "You are, I see, a d----d set of butchers; take away as much blood as you like." "We seized the opportunity," says Dr. Milligan, "and drew twenty ounces; yet the relief did not correspond to the hopes we had formed." On the 17th, the bleeding was twice repeated, dangerous symptoms still increasing, and on the 19th he expired, just about bled to death. Washington, a man whose name is dear to every American, died from the effects of an evil system of medication. He was attacked with croup: his physician bled him, and gave him calomel and antimony. The next day, physicians were called in, (to share the responsibility of the butchery,) and he was subjected to two more copious bleedings: in all he lost ninety ounces of blood. Which of our readers, at the present day, would submit to such unwarrantable barbarity? We just said we were not writing for doctors; yet we find ourselves off the track in thus administering a small dose, as a sample of "_good and efficient treatment_."

In reference to the success attending our labors in veterinary reform, we do not claim the whole credit: much of it is due to the intelligence of the American farmers, in appreciating the value and importance of a safer and a more effectual system of medication; such a system as we advocate. They have witnessed the results attending the practice of cattle doctors generally, and they have seen the results of our sanative system of medication, and a great majority in Massachusetts have decided in favor of the latter. We have demonstrated to the satisfaction of our patrons, and we are ready and willing to repeat our experiments on diseased animals for the satisfaction of others, in showing that we can restore an animal, when suffering under acute attacks of disease, in a few hours, when, by the popular method, it takes weeks and months, if indeed they ever recover from the effects of the destructive agents used.

We are told that "horses and cattle are bled and get well immediately." This may apply to some cases; but, in very many instances, the animals are sent for a few weeks to "Dr. Green,"[1] to put them in the same condition they were at the time of bleeding. But suppose that some animals do get well after bleeding; is it thus proved that more would not get well if no blood were drawn from any? A cow may fall down, and, in so doing, lacerate her muscles, blood-vessels, &c., and lose a large quantity of blood. She may get well, in spite of the violence and loss of blood. So we say of blood-letting, if the abstraction of a certain number of gallons of blood will kill a strong animal, then the abstraction of a small quantity must injure it proportionately.