25 Loc. cit.
The microcytes which occur in numbers in blood in some cases of traumatic anæmia have been regarded as young developmental forms, but there is a great diversity of opinion as to their real nature, and their connection with productive blood-processes is somewhat doubtful.
Cohnheim suggests26 that after a profuse hemorrhage the rapid consumption of red corpuscles may be reduced, in which case we need not suppose such an active development; but the fact noted by Lyon27 and others of the increased reduction after a bleeding is against the view. In any case, if Quincke is right in assuming that the average life of a red corpuscle is only three or four weeks, what is the restitution of a couple of millions of corpuscles per cubic millimeter in comparison with the monthly renovation of the entire mass?
26 Loc. cit.
27 Loc. cit.
In the regeneration of the blood the development of the hæmoglobin does not keep pace with that of the corpuscles, so that they may, even when normal in amount, have a lowered hæmoglobin percentage, indicated under the microscope by a paleness in the cells.
2d. There is a large group of cases in which the anæmia is induced by a long-continued drain on the albuminous material of the blood—pus in a chronic suppuration, albumen in Bright's disease, prolonged lactation, etc. Rapidly-growing tumors act in the same way.
3d. The anæmia of inanition, brought about by defective food-supply or by conditions of the digestive organs which interfere with the proper reception and preparation of nourishment, as cancer of the gullet, chronic dyspepsia, etc. The reduction in the blood-mass may be extreme, but the plasma suffers proportionately more than the corpuscles, which even in the extreme wasting of cancer of the oesophagus may not be reduced more than one-half or three-fourths.
4th. Toxic anæmia, induced by the action of certain poisons in the blood, such as lead, mercury, and arsenic among inorganic substances, and the virus of syphilis and malaria among organic poisons. They act by increasing the rate of consumption of the red corpuscles, and the reduction may be considerable. The gradual impoverishment of the blood in pyrexia may be in part due to the toxic action of the fever-producing agent on the blood itself; but in this there is probably also disturbance of function in the blood-making organs.
The last three groups comprise what are known as secondary anæmias, and the condition of the blood is characterized by an increase in the water and diminution in the albuminous elements; the fibrin is often increased, and the network which separates, as seen under the microscope, is unusually dense; the white corpuscles are not much increased; there is rarely microcytosis or poikilocytosis; the reduction in the number of red corpuscles is not so great; hemorrhages do not often occur; when fever is present it is due to the disease or some complication, and is not the pyrexia of anæmia; and, lastly, they are more or less amenable to the action of iron and other remedies.