The term Anaemia would mean literally want of blood, but it is used in a wider sense to indicate defect in any of the essential constituents of the blood As the red corpuscles are, so far as the general function of the blood is concerned, the chief constituents, the term anaemia is given' to' conditions in which these elements are defective either in number or in their characteristic pigment. Spanaemia, which means poverty of blood, would more strictly designate these conditions, but this term is seldom used.

As the blood may be defective in its various constituents different terms are used to indicate the character of the defect. Oligemia is a defect in the bulk of the blood as a whole, such as results from a severe haemorrhage, and it is virtually equivalent to Acute traumatic anaemia. Oligocythemia is a defect in the number of the red corpuscles. This condition is sometimes called Aglobulism. When the red corpuscles, although, perhaps, normal in number, are deficient in haemoglobin, the condition is called Achromatosis. A watery or dilute condition of the liquor sanguinis is called Hydrsemia. As the essential constituent of the blood plasma is albumen, the term Hypalbuminosis is used instead of hydremia, especially in cases where there is a direct drain on the albumen.

1. Causation

We have here to do with defects in the red corpuscles, and such defects may arise either by destruction of the corpuscles or by some fault in their formation.

(A) Anaemia From Destruction Of The Corpuscles

This occurs most directly in haemorrhages where the blood-corpuscles, like the rest of the constituents, are shed.

Destruction of the corpuscles in the circulating blood is met with in a variety of conditions. It occurs very directly in malarial fevers, by the action of the parasites concerned in the causation of this class of disease. The anaemia produced is a very striking and frequent feature. In some malarial fevers, especially the severe forms of African fever, haematuria is mentioned as a frequent symptom. This is really a Haemoglobinuria due to the solution of the red corpuscles. In Texas fever of cattle, which seems to be due to a similar parasite, a striking symptom is bloody urine, which gives the popular name of "red water " to the disease. The author has found this to be a haemoglobinuria and not a haematuria.

Haemoglobinuria is also of occasional occurrence in burns which involve extensive tracts of skin, also in pyaemia, in certain fevers, and, as a special form, in Paroxysmal haemoglobinuria.

Hemoglobinuria (Hoemoylobiruemia)

We have already considered at p. 67 the mode of occurrence of haemoglobinuria when alien blood is transfused. It has been also produced artificially by the injection of distilled water, of biliary acids and diluted glycerine. Extensive burns of the skin, by destroying the vitality of the corpuscles in the vessels exposed to the high temperature, induce their ultimate solution. Certain poisons also partially dissolve the corpuscles, especially arsenic, arseniuretted hydrogen, toluylendiamin, nitric acid. It occurs also in new-born children. (See under Icterus).

Paroxysmal hemoglobinuria is a condition in which the red corpuscles are peculiarly susceptible of solution, which is induced by slight causes. The commonest cause is exposure to cold, but a case is recorded in which it always occurred in a soldier after a long march. As exposure of the surface to cold is the usual cause, the affection occurs mostly in winter, but Rosenbach produced it in summer by a cold foot bath. The haemoglobin is set free by the solution of the corpuscles. Ehrlich, in a case of this kind, put an elastic ligature round the finger and immersed the latter in ice-cold water. A drop of blood from the finger showed the corpuscles in various stages of decolorization, and also altered in size and shape (microcytes and poikilocytes). The urine in hemoglobinuria gives a precipitate on heating like that of albumen, but this is haemoglobin. The haemoglobin is found in the urine in the form of little beads, often in rows, and sometimes forming casts of the uriniferous tubules.

The free haemoglobin may stain the tissues, but this does not usually occur unless the haemoglobin is transformed into haematoidin. The so-called hsmatogenous icterus, observed in pyaemia and other conditions, has this origin. (See under Icterus.) Eecklinghausen found crystals of haematoidin in the blood in a case in which lamb's blood had been used for transfusion.

A more obscure mode of destruction is that which occurs in pernicious anaemia, where a progressive diminution of the red corpuscles is met with. That this is due to destruction of the red corpuscles is evidenced by the striking deposition of pigment in the liver which is characteristic of this disease.

(B) Anaemia From Defective Formation Of The Corpuscles

This is the condition in chlorosis, where a defect in the blood-forming organs is probable. Secondary anaemias also belong to this category. In them there is some defect in the general conditions of life or some grave disease which, by lowering the nutrition as a whole, leads to defect in the blood.