own individual features[34].

* * * * *

It is of special importance to study the changes due to certain
intercurrent diseases in the blood picture of medullary leukaemia. This
point has recently been the object of detailed investigation, in
particular by A. Fraenkel, Lichtheim and others[35]. According to these
authors, under the influence of febrile diseases the total number of
leucocytes may be enormously decreased. The blood moreover is altered,
so that the myelaemic characteristics become less marked, and the
polynuclear neutrophil elements largely preponderate. The latter may
attain the percentage numbers of common leucocytosis up to 90% and
over.

We will here mention a few rare cases, demanding special attention,
shewing the alterations leukaemic blood may undergo, and occasionally
presenting almost insuperable difficulties in diagnosis. We find but a
single case of this kind mentioned in the literature. Zappert reported a
patient, who in February, 1892, had shewn the typical signs of
myelogenic leukaemia. Amongst others the relation of white to red cells
was found to be 1:4.92, and 1400 eosinophil cells per mm.^{3} (3.4%)
were counted. At the end of September of the same year the patient was
brought in a miserable condition to the hospital, where she soon died
with gradually failing strength. During this period of observation the
proportion of white to red was 1:1.5; the percentage of eosinophils,
0.43; the mononuclears, most of which had no neutrophil granulation,
amounted to 70% of the leucocytes. Zappert expressly mentions that these
mononuclear cells were in no way similar to the lymphocytes in general
appearance. At the autopsy Zappert found the bone-marrow studded with
non-granulated mononuclear cells, and the eosinophil cells were much
more scanty than is usually the case in leukaemic bone-marrow.
Blachstein, under Ehrlich's direction, investigated a second case of
this kind. This patient had also been the subject of exact clinical
investigations for some time on account of a myelogenic leukaemia. During
the time he was last in hospital the blood could only be examined a day
before the fatal termination, the direct consequence of a septic
complication. With a markedly leukaemic constitution of the blood there
were found 62% polynuclear cells, 17.5% mononuclear about the size of
the ordinary myelocyte, 0.75% eosinophil cells, nucleated red blood
corpuscles in moderate amo