nic
leukaemia is an active leucocytosis is, that pus artificially produced in
leukaemic patients has nearly always the histological constitution of
normal pus. But from our previous detailed remarks we should only expect
a myelaemic constitution of the pus, if the specific morbid agent of
leukaemia were present in a concentrated form at the place of
inflammation. Just as we saw in pemphigus, Neusser's eosinophilous
suppuration occurred only in the specific pemphigus bullae, but not in
the foci of suppuration that were artificially produced. We know that
the myelocytes are in no way positively influenced by the chemiotactic
stimuli of ordinary infectious agents. On the contrary, it clearly
follows from the above-mentioned observations on the transformation of
leukaemic blood under the influence of infectious diseases, that the
common bacterial poisons act in a negatively chemiotactic sense, both on
the eosinophil and on the neutrophil mononuclear cells. Under these
circumstances we should indeed expect that artificially produced
suppuration in leukaemic patients would have, not a myelaemic, but a
polynuclear neutrophil character.

It will be the task of further investigations to examine accurately
inflammatory products, _e.g._ pleuritic exudations, in leukaemic
patients, with the object of elucidating the question, whether under
special conditions of disease all the leucocytes characteristic for
leukaemia may not be able to wander from the blood. Thus in a case of
pleurisy in a leukaemic patient, Ehrlich received the impression from the
preparations that a "myeloid" emigration had in fact occurred, carrying
all the elements in the blood into the exudation. This observation does
not prove the point, for numerical estimation of the proportion of white
to red blood corpuscles in the exudation was not made. And these
estimations are necessary in order to prove indisputably the active
emigration of the white blood corpuscles into the exudation, and to
exclude their purely mechanical passage, _per rhexin_, from the
blood-stream.

The hypothesis of the active origin of myelaemia is considerably
supported by a further train of argument. In leukaemia, besides the
myelocytes, the polynuclear leucocytes are also enormously increased,
and their active emigration is beyond doubt. And the view, that the
mononuclear cells are washed into the blood, excludes that of a single
mode of origin of the leukaemic blood condition; and commits