e blood corpuscles was brought about
in the circulating blood itself, an assumption specially supported by
Loewit.

A large number of authors (H. F. Mueller, Wertheim, Rieder) have
demonstrated mitoses, particularly of the myelocytes, in the circulating
blood in leukaemia. No =diagnostic= importance of any kind can however be
ascribed to them. They are found in all cases only in very small
numbers. Thus Mueller 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 leukaemia they are valueless.

6. =Nucleated red corpuscles= form a constant constituent of leukaemic
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 leukaemia may be either a specific
phenomenon, or merely the expression of an anaemia accompanying the
leukaemia. We are inclined to the first supposition, since the occurrence
in such numbers of nucleated red cells is hardly ever observed in other
anaemias of the same severity.

So much for the characteristics of leukaemic blood, upon which the
diagnosis of the disease is made. We must add that although in any case
of medullary leukaemia 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