"

Of great theoretical interest is the contrast between eosinophil and
neutrophil cells. At the height of ordinary leucocytosis, the number of
eosinophil cells is diminished often to disappearance; whilst during its
decline they occur in abnormally high numbers. Hence it follows that the
eosinophil and neutrophil cells must react towards stimulating
substances completely differently, and in a certain sense oppositely[27].

It seems, generally speaking, that the bacterial =metabolic products
formed in human diseases which are positively chemiotactic for the
polynuclear neutrophil cells are negatively chemiotactic= for the
eosinophils, and _vice versa_.

The explanation of the individual clinical forms of leucocytosis is
self-evident from the above description. The occurrence of physiological
and inflammatory leucocytosis is exclusively to be explained by
chemiotaxis. In the other forms, however, other factors also come into
play, in particular the increased activity of the bone-marrow, or the
extensive transformation of fatty to red marrow, causing a large fresh
formation of leucocytes.

[alpha] 2. ~Polynuclear eosinophil leucocytosis. Mast cells.~

Our knowledge of eosinophil leucocytosis is still of comparatively
recent date. After Ehrlich demonstrated the constant increase of the
eosinophil cells in leukaemia a considerable time elapsed before an
eosinophilia was found in other diseases, an eosinophilia however that
differs in its essential traits from the leukaemic type. To Friedrich
Mueller we owe the first researches in this direction, at whose
suggestion Gollasch investigated the blood of persons suffering from
asthma; in which he was able to demonstrate a considerable increase of
the eosinophil cells. This was followed by the researches of H. F.
Mueller and Rieder, who discovered the frequency of eosinophilia in
children, and its presence in chronic splenic tumours; further by the
well-known work of Ed. Neusser, who observed a quite astounding
increase of the oxyphil elements in pemphigus, and by the almost
simultaneous analogous observations of Canon in chronic skin diseases.
From amongst the flood of further papers upon this condition we will
only mention the comprehensive account of the subject by Zappert.

By =eosinophilia= we understand an =increase only of the polynuclear
eosinophil cells in the blood=. Confusion of this form of leucocytosis
with leukaemia is quite impossible, because a good number