A large number of authors (H. F. Müller, Wertheim, Rieder) have demonstrated mitoses, particularly of the myelocytes, in the circulating blood in leukæmia. No =diagnostic= importance of any kind can however be ascribed to them. They are found in all cases only in very small numbers. Thus Müller says that he generally must look through many thousands of white cells before meeting one mitosis. Only in one case did he find the figures of nuclear division somewhat more abundant, where there was one mitosis only to several hundreds of leucocytes.
These really negative observations shew that the mitoses play a completely negligeable part in the increase of the cells in the blood itself. For the diagnosis of leukæmia they are valueless.
6. =Nucleated red corpuscles= form a constant constituent of leukæmic blood. In different cases their number is very varying; in one case they occur extremely sparingly, in another every field contains very many. The normoblastic type is found most frequently, but side by side with it, megaloblasts and forms transitional between the two are occasionally found. Mitoses within the red blood discs have been described by different authors, but possess no theoretic or clinical importance. The appearance of erythroblasts in leukæmia may be either a specific phenomenon, or merely the expression of an anæmia accompanying the leukæmia. We are inclined to the first supposition, since the occurrence in such numbers of nucleated red cells is hardly ever observed in other anæmias of the same severity.
So much for the characteristics of leukæmic blood, upon which the diagnosis of the disease is made. We must add that although in any case of medullary leukæmia each particular factor described is to be recognised, yet the manner of its appearance, its numerical relation to the others and to the total blood varies extremely. Apart from the degree of increase of the leucocytes, no one case is the same as another with regard to the other anomalies. In one case the blood bears a large-celled, mononuclear neutrophil character; in another the increase of the eosinophil cells predominates; in a third the nucleated red blood corpuscles preponderate; in a fourth we see a flooding of the blood with mast cells. And hence results a multiplicity of combinations, and each single case has its own individual features[34].
