| Case | 29 | 3.5% | eos. | 14,000 | per mm.3 |
| " | 30 | 3.9% | " | 8,000 | " |
| " | 31 | 3.4% | " | 11,000 | " |
The figure given by Zappert as a high normal value is 250. In these cases there is an average number of 11,000, that is 50 times as great. The observations then of Müller and Rieder themselves suffice fully to confirm Ehrlich's statement.
The absolute number of eosinophil cells depends naturally to a certain extent on the relative proportion of white to red corpuscles, and the greater the relative number of leucocytes, the greater should be the number of eosinophils. Zappert, for instance, found the following figures in his cases:
| Proportion of white to red corpuscles. | Absolute number of eosinophils. |
| 1:24 | 3,000-4,560 |
| 1:18 | 3,300 |
| 1:15 | 7,000 |
| 1:13 | 8,700 |
| 1:11 | 6,000 |
| 1:7.6 | 8,300 |
| 1:7.0 | 7,600 |
| 1:7.0 | 29,000 |
| 1:5.0 | 14,000 |
| 1:3.8 | 34,000. |
Apart from the approximate parallelism between the two rows of figures, this abstract shews that the minimal value—3,000 eosinophils with a proportion of white to red of 1:24—still amounts to 15 times the normal. The maximal figure found by Zappert of 30,000 is moreover by no means to be considered extreme. Cases of leukæmia are not infrequent in which we find 100,000 eosinophils per mm.3 and over.
From these figures it must be admitted that the absolute increase of the eosinophil cells in medullary leukæmia is not "alleged" (v. Limbeck) but on the contrary is very real and considerable.
That the absolute and relative number of eosinophil cells may markedly sink in certain complications of leukæmia, constitutes no exception to the law that the eosinophil cells are increased in myelogenic leukæmia. In this connexion the self-evident principle must be observed, that only analogous conditions are comparable. The standard of comparison for a leukæmic patient suffering from severe sepsis is not the blood of a healthy person with normal numerical proportions, but that of a patient similarly attacked by a severe sepsis. Now we know that in sepsis the number of eosinophil cells is enormously diminished, so that Zappert, in five cases of this nature, was unable to recognise any eosinophils in the blood. In contrast to this stands a case of myelogenic leukæmia described by Rieder and Müller, complicated by a severe and lethally ending suppurative process. In consequence of the acute neutrophil leucocytosis brought about by the septic infection, the number of eosinophils sank rapidly from 3.5% to 0.43% (4 hours before death). The absolute number of eosinophil cells however in this terminal stage still amounted to 1400-1500 per mm.3, and was therefore, in comparison with an uncomplicated sepsis, very much raised. Writers should not have disputed the importance of the eosinophil cells for the diagnosis of leukæmia from cases like these; on the contrary they should have seen in them a decisive confirmation of the constancy of the absolute increase of the eosinophils in leukæmic blood.
At the time when Ehrlich formulated his proposition on the diagnostic importance of the eosinophil cells in leukæmia, the simple eosinophil leucocytosis (see p. 148), first discovered later by the investigation of asthma etc., was unknown. For no confusion can arise between leukæmia, and conditions accompanied by eosinophilia, as they can be distinguished on clinical grounds alone. The blood moreover provides ample means for a differential diagnosis: (1) the total increase of the white cells in this case seldom reaches degrees that remind one of leukæmia; (2) the eosinophil cells are exclusively polynuclear; (3) mast cells and neutrophil myelocytes are almost entirely absent.
In favour of the diagnostic value of the absolute increase of the eosinophil cells are those cases too, where with a blood condition closely recalling leukæmia, the absence of eosinophil cells excludes the diagnosis of that disease. In a case of carcinoma of the bone-marrow, described by Epstein, with an anæmic constitution of the blood (nearly always present it may be mentioned in leukæmia), there was found a marked increase of the white blood corpuscles, numerous neutrophil myelocytes and nucleated red corpuscles. Anyone holding, as Müller and Rieder do, that the number of eosinophil cells need not be considered in the diagnosis, must in this case have diagnosed myelogenic leukæmia. This however was according to Ehrlich's system impossible owing to the complete absence of eosinophil cells.
From all these observations it follows that an absolute increase of eosinophil cells is indispensable for the diagnosis of leukæmia.