epeated experience
with special distinctness, for some recent authors do not even yet allow
the full diagnostic importance of the blood examination. v. Limbeck says
in the latest edition of his clinical _Pathology of the Blood_, "That
one should not regard the blood changes as an invariably reliable
diagnostic resource in myelogenic leukaemia; and that the diagnosis of
leukaemia should not rest on the presence or significance of one or more
cells. Not only the general features of the case, but the blood
condition as well should be considered." To these remarks the objection
must be made that up to the present no serious haematologist will have
had to diagnose a leukaemic disease principally "from the presence of one
or more cells." In the work of Ehrlich and his pupils at least, it has
always been shewn that the character of a leukaemic condition is only
settled by a concurrence of a large number of single symptoms, of which
each one is indispensable for the diagnosis, and which taken together
are absolutely conclusive. With these premises it is indisputable =that
the microscopic examination of the blood alone on dry preparations,
without the assistance of any other clinical method, can decide whether
a patient suffers from leukaemia, and whether it belongs to the lymphatic
or myelogenic variety=.

The microscopic picture of =myelogenic leukaemia=, disregarding the almost
constant increase of the white blood corpuscles, has a varied, highly
inconstant character. This arises from the co-operation of several
anomalies, namely:

A. =that in addition to the polynuclear cells, their early stages, the
mononuclear granulated corpuscles likewise circulate in the blood=;

B. =that all three types of granulated cells, the neutrophil, eosinophil,
and mast cells participate in the increase of the white blood
corpuscles=;

C. =that atypical cell-forms appear=, _e.g._ =dwarf forms of all the kinds
of white corpuscles; and further mitotic nuclear figures=;

D. =that the blood always contains nucleated red blood corpuscles, often
in great numbers=.

1. We begin with the discussion of the =mononuclear neutrophil cells=,
Ehrlich's "=myelocytes=." They are present so abundantly in the blood of
medullary leukaemia as to impart to the whole picture a predominantly
mononuclear character. As we have frequently mentioned, myelocytes occur
normally only in the bone-marrow, not in the circulating blood. Their
eminent importance for the di