This toxaemia affects the marrow and through it the blood, the gastro-intestinal apparatus and the nervous system, especially the spinal cord, in different proportions in different cases. The effect upon the marrow is to alter the type of red corpuscle formation, causing a reversion to the embryonic condition, in which the nucleated red corpuscles are large (megaloblasts), and the corpuscles in the blood formed from them are also large, are apparently ill suited to the needs of the adult, and easily break down, as the deposits of iron in the liver, spleen, kidneys and marrow prove. Whether this reversion is due to an exhaustion of the normal process or to an inhibition of it is not definitely known. The result is that the circulating red corpuscles are enormously diminished; it is usual to find 1,000,000 or less in the cubic millimetre instead of the normal 5,000,000. Though the haemoglobin is of course absolutely diminished, it is always, in severe cases, present in relatively higher percentage than the red corpuscles, because the average red corpuscle is larger and contains more haemoglobin than the normal. The large nucleated red corpuscles (megaloblasts) with which the marrow is crowded, often appear in the blood.
Other anaemias, such as those known as lymphadenoma, or Hodgkin’s disease, splenic anaemia, chloroma, leucanaemia and the anaemia pseudo-leucaemica of children, need not be described here, as they are either rare or their occurrence or nature is still too much under discussion.
The number and nature of the leucocytes in the blood bears no constant or necessary relation to the number or condition of the red corpuscles, and their variations depend on entirely different conditions. The number in the Leucocytosis. cubic millimetre is usually about 7000, but may vary in health from 5000 to 10,000. A diminution in their number is known as leucopenia, and is found in starvation, in some infective diseases, as for example in typhoid fever, in malaria and Malta fever, and in pernicious anaemia. An increase is very much more frequent, and is known as leucocytosis, though in this term is usually connoted a relative increase in the proportion of the polymorphonuclear neutrophile leucocytes. Leucocytosis occurs under a great variety of conditions, normally to a slight extent during digestion, during pregnancy, and after violent exercise, and abnormally after haemorrhage, in the course of inflammations and many infective diseases, in malignant disease, in such toxic states as uraemia, and after the ingestion of nuclein and other substances. It does not occur in some infective diseases, the most important of which are typhoid fever, malaria, influenza, measles and uncomplicated tuberculosis. In all cases where it is sufficiently severe and long continued, the reserve space in the bone-marrow is filled up by the active proliferation of the leucocytes normally found there, and is used as a nursery for the leucocytes required in the blood. In many cases leucocytosis is known to be associated with the defence of the organism from injurious influences, and its amount depends on the relation between the severity of the attack and the power of resistance. There may be an increase in the proportions present in the blood of lymphocytes (lymphocytosis), and of eosinophile cells (eosinophilia). This latter change is associated specially with some forms of asthma, with certain skin diseases, and with the presence of animal parasites in the body, such as ankylostoma and filaria.
The disease in which the number of leucocytes in the blood is greatest is leucocythaemia or leucaemia. There are two main forms of this disease, in both of which there are anaemia, enlargement of the spleen and lymphatic Leucaemia. glands, or of either of them, leucocytic hypertrophy of the bone-marrow, and deposits of leucocytes in the liver, kidney and other organs. The difference lies in the kind of leucocytes present in excess in the blood, blood-forming organs and deposits in the tissues. In the one form these are lymphocytes, which are found in health mainly in the marrow, the blood itself, the lymph glands and in the lymphatic tissue round the alimentary canal; in the other they are the kinds of leucocytes normally found in the bone-marrow-myelocytes, neutrophile, basophile and eosinophile, and polymorphonuclear cells, also neutrophile, basophile and eosinophile. The clinical course of the two forms may differ. The first, known as lymphatic leucaemia or lymphaemia, may be acute, and prove fatal in a few weeks or even days with rapidly advancing anaemia, or may be chronic and last for one or two years or longer. The second, known as spleno-myelogenous leucaemia or myelaemia, is almost always chronic, and may last for several years. Recovery does not take place, though remissions may occur. The use of the X-rays has been found to influence the course of this disease very favourably. The most recent view of the pathology of the disease is that it is due to an overgrowth of the bone-marrow leucocytes, analogous in some respects to tumour growth and caused by the removal of some controlling mechanism rather than by stimulation. The anaemia accompanying the disease is due partly to the leucocyte overgrowth, which takes up the space in the marrow belonging of right to red corpuscle formation and interferes with it.
(G. L. G.)
[1] The suffix -phile, Greek φιλεῖν, to love, prefer, is in scientific terminology frequently applied to substances that exhibit such preference for particular stains or reagents, the names of which form the first part of the word.
BLOOD-LETTING. There are certain morbid conditions when a patient may obtain marked relief from the abstraction of a certain amount of blood, from three or four ounces up to twenty or even thirty in extreme cases. This may be effected by venesection, or the application of leeches, or more rarely by cupping (q.v.). Unfortunately, in years gone by, blood-letting was used to such excess, as a cure for almost every known disease, that public opinion is now extremely opposed to it. In certain pathological conditions, however, it brings relief and saves life when no other means would act with sufficient promptness to take its place.
Venesection, in which the blood is usually withdrawn from the median-basilic vein of the arm, has the disadvantage that it can only be performed by the medical man, and that the patient’s friends are generally very much opposed to the idea. But the public are not nearly so prejudiced against the use of leeches; and as the nurse in charge can be instructed to use these if occasion arises, this is the form of blood-letting usually practised to-day. From one to twelve leeches are applied at the time, the average leech withdrawing some two drachms of blood. Should this prove insufficient, as much again can be abstracted by the immediate application of hot fomentations to the wounds. They should always be applied over some bony prominence, that pressure may be effectively used to stop the haemorrhage afterwards. They should never be placed over superficial veins, or where there is much loose subcutaneous tissue. If, as is often the case, there is any difficulty in making them bite, the skin should be pricked at the desired spot with the point of a sterilized needle, and the leech will then attach itself without further trouble. Also they must be left to fall off of their own accord, the nurse never dragging them forcibly off. If cold and pressure fail to stop the subsequent haemorrhage, a little powdered alum or other styptic may be inserted in the wound. The following are the main indications for their use, though in some cases they are better replaced by venesection, (1) For stagnation of blood on the right side of the heart with constant dyspnoea, cyanosis, &c. In acute lung disease, the sudden obstruction to the passage of blood through the lungs throws such an increased strain on the right ventricle that it may dilate to the verge of paralysis; but by lessening the total volume of blood, the heart’s work is lightened for a time, and the danger at the moment tided over. This is a condition frequently met with in the early stages of acute pneumonia, pleurisy and bronchitis, when the obstruction is in the lungs, the heart being normal. But the same result is also met with as a result of failure of compensation with back pressure in certain forms of heart disease (q.v.). (2) To lower arterial tension. In the early stages of cerebral haemorrhage (before coma has supervened), when the heart is working vigorously and the tension of the pulse is high, a timely venesection may lead to arrest of the haemorrhage by lowering the blood pressure and so giving the blood in the ruptured vessel an opportunity to coagulate. (3) In various convulsive attacks, as in acute uraemia.