n bluish-red
in eosine-methylene blue after long fixing in superheated steam: in the
transitional stages this admixture is gradually lost, and finally
completely vanishes in the granules of the polynuclear leucocytes which
stain pure red. Analogous observations may be made in the eosinophil
cells of man and animals, and in the neutrophils of man. Hence it is
even possible to decide whether an isolated granule belonged to an old
or to a young cell.

It is still impossible to judge with certainty the rate at which the
ripening of the mononuclear to the polynuclear cells proceeds, or
further to decide if the ripening of the granules always runs parallel
in point of time with that of the whole cell. On the grounds of our
observations we would suppose that in general the two processes run
their course side by side, but that in special cases the morphological
ripening of the cell may proceed more rapidly than that of the granules.
It is particularly easy to observe this point in eosinophil cells.
Ehrlich had already mentioned in his first paper (1878) that side by
side with the typical eosinophil granules isolated granules are often
found which shew a deviation in tinctorial properties: for instance,
they stain more of a black colour in eosine-aurantia-nigrosin; in
eosine-methylene-blue, bluish-red to pure blue. Ehrlich had already
described these as young elements in his first paper. The same
differences are found more sharply marked in leukaemia even in the
circulating blood, in the neutrophil as well as in the eosinophil group.
Ehrlich has repeatedly found in leukaemic blood polynuclear eosinophil
cells, whose granules must almost exclusively be regarded as young
forms[15].

Ehrlich regarded these as typical examples of a relative acceleration of
the morphological ripening of the cells, as compared with the
development of the granules.

=In normal blood we find only the ripe forms of the specific granulated
cells of the bone-marrow. The mononuclear and transitional forms of the
neutrophil group, do not under normal circumstances pass over into the
blood-stream.=

Ehrlich regarded the mononuclear neutrophil granulated cells as
characteristic for the bone-marrow, since they are found exclusively in
the bone-marrow, never in the spleen or lymph glands, and for this
reason named them "=myelocytes=," [Greek: kat' exochen][16]. When
myelocytes, no matter of what size, appear in considerable numbers in
the blood of an adult