Ehrlich put forward the theory, that this remarkable behaviour towards dyes indicates a gradual death of the red blood corpuscles, that is of the old forms, leading to a coagulation necrosis of the discoplasm. The latter takes up, as is the case in coagulation necrosis, the proteids of the blood, and acquires thereby the power of combining with nuclear stains. At the same time the discoplasm loses its power of retaining the hæmoglobin, and gives it up to the blood plasma in ever increasing quantity as the change proceeds. Hence the disc continues to lose the capacity for the specific hæmoglobin stain.
Objection has been raised to these views from many quarters, especially from Gabritschewski, and afterwards from Askanazy, Dunin and others. The polychromatophil discs are not, they say, dying forms, but on the contrary represent young individuals. The circumstance, that in certain anæmias the early stages of the nucleated red corpuscles are variously polychromatic, was evidence for this opinion.
In view of the great theoretical importance which attaches to this subject, the grounds for regarding this change as degenerative, may be here shortly brought forward.
1. The appearance of the erythrocytes which shew polychromatophilia in the highest degree. By the notching of their margins they appear to eyes practised in the judgment of morphological conditions, in a stage almost of dissolution, and as well-pronounced degeneration forms.
2. The fact that by animal experiment, for instance, in inanition, their appearance in large numbers in the blood can be produced. That is, precisely in conditions, where there can be least question of a fresh production of red blood corpuscles.
3. The clinical experience, that in acute losses of blood in man, these staining anomalies, can be observed in numerous cells, within so short a time as the first 24 hours. Whilst in our observations, which are very numerous upon this point, embracing several hundred cases, and carried out with particular care, no nucleated red blood corpuscles in this space of time can be found in man[8].
4. The polychromatophil degeneration can frequently be observed in nucleated red blood corpuscles, particularly in the megaloblasts. This fact can be so easily established that it can hardly escape even an unpractised observer, and it was sufficiently familiar to Ehrlich, who first directed attention to these conditions. The fact that the normoblasts, which are typical of normal regeneration, are as a rule free from polychromatophil degeneration, gave the key for the interpretation of this appearance. And similarly for the nucleated red blood corpuscles of lower animals. Askanazy asserts that the nucleated red blood corpuscles of the bone-marrow, which he was able to investigate in a case of empyema, shew, immediately after the resection of the ribs, complete polychromatophilia. This perhaps depends on the peculiarities of the case, or on the uncertainty of the staining method: eosine-methylene blue stain, which is for this purpose very unreliable, since slight overstaining towards blue readily occurs. (We expressly advise the use of the triacid solution or of the hæmatoxylin-eosine mixture for the study of the anæmic degenerations.)
After what has been adduced, we hold in agreement with the recent work of Pappenheim, and Maragliano, that the appearance of polychromatophilia is a sign of degeneration. To explain the presence of erythroblasts which have undergone these changes we must suppose that in severe injuries to the life of the blood these elements are not produced in the usual fashion, but from the very beginning are morbidly altered. Analogies from general pathology suggest themselves in sufficient number.
B. A second change that we find in the red blood corpuscles of the anæmias, is poikilocytosis.
By this name a change of the blood is denoted, where along with normal red blood corpuscles, larger, smaller and minute red elements are found in greater or less number. The excessively large cells are found in pernicious anæmia, as Laache first observed, and as has since been generally confirmed. On the contrary in all other severe or moderate anæmic conditions, the red corpuscles shew a diminution in volume, and in their amount of hæmoglobin. This contradiction, which Laache first mentioned, but was unable to explain, has found a satisfactory solution in Ehrlich's researches on the nucleated precursors of the myelocytes and normocytes (see below).