connective
tissue cells[29]; but that the same holds good for the eosinophil cells
as well, has nowise as yet been proved. Secondly, it is conceivable,
that isolated eosinophil cells, pre-existing in the tissues, should
rapidly multiply, and so produce the local accumulation only. Numerous
mitoses could be considered an adequate proof of this process. But so
far no figures of nuclear division have been observed; indeed A.
Schmidt, who has directed special experiments thereto from the
standpoint of his theory, has found them entirely absent.

As a =third= possibility for the local origin of the eosinophil cells,
their direct descent from neutrophil cells is conceivable, and is by
many regarded as a kind of ripening. This assumption nevertheless must
be described as unsound, since the necessary condition of its
foundation, namely the observation of corresponding transitional stages,
has not so far been fulfilled.

By the inductive method then we conclude that a local origin of the
eosinophil cells can hardly come under discussion. And this conclusion
is strengthened by comparison with the behaviour of the mast cells,
which are related to the eosinophils in many points, and only differ
from them essentially in the nature of their granulation. The mast cells
too, like the eosinophils, form a normal constituent of the bone-marrow,
and occur regularly besides in normal blood, though in very small
number--according to Canon they amount to 0.28% of the leucocytes. We
know that the mast cells are produced in large quantities locally,
wherever an over-nutrition of the connective tissue occurs, for instance
in chronic diseases of the skin, elephantiasis, brown induration of the
lungs. In the case of the mast cells, then, we see the conditions
actually realised, which the supporters of the theory of the local
origin of the eosinophil cells only assume. We should therefore expect
that an increase of mast cells in the blood or in certain inflammatory
exudations would be by no means seldom. With this point in mind Ehrlich
has subjected the sputum in emphysema and brown induration of the lungs
to exact examination for 20 years. Nevertheless he has obtained =entirely
negative= results. The special blood investigations of Canon have
likewise proved to be practically negative. In 22 healthy persons Canon
entirely failed to find the mast cells on nine occasions, in the others
he found on the average 0.47%; the highest percentage number o