cases, though not constantly and in much smaller number. Tuerk has
recently undertaken a very exact and thorough analysis of their
occurrence in infectious diseases, in the course of which he accurately
tabulated the white corpuscles in a large number of cases. The results
he obtained in pneumonia are especially characteristic, for he found at
the commencement of the disease that myelocytes are not seen at all or
only very scantily: and it is only at the time of the crisis, or
directly afterwards, that they become specially numerous. In isolated
cases the increase at this time was very considerable; and in one case
amounted almost to 12% of all neutrophil cells.

2. Mononuclear eosinophil cells ("=eosinophil myelocytes="). H. F. Mueller
was the first to point out their importance. They constitute the
eosinophil analogue of the previous group, and are much larger than the
polynuclear eosinophils; medium and small sized examples are often found
in leukaemia. Eosinophil myelocytes are almost constantly present in
myelogenous leukaemia and in anaemia pseudolymphatica infantum. Apart from
these two diseases they are very rarely found; Mendel saw them for
example in a case of myxoedema, Tuerk quite exceptionally in some
infectious diseases.

3. =Small neutrophil pseudolymphocytes.= They are about as large as the
small lymphocytes, possess a rounded deeply stained nucleus, and a small
shell of protoplasm studded with a neutrophil granulation. The
relatively deep stain of the nucleus and the small share of the
protoplasm in the total cell body prevent confusion with the small forms
of myelocytes, which never reach such small dimensions. The neutrophil
pseudolymphocytes are exceedingly infrequent, and represent products of
division of the polynuclear cells; they were first described by Ehrlich
in a case of hemorrhagic small-pox. The process of division goes on in
the blood in such a manner that the nuclear rod first divides into two
to four single nuclei, and then the whole cell splits up into as many
fragments. These cells occur also in fresh pleuritic exudations. After a
time the nucleus of these cells becomes free, and the little masses of
protoplasm thus cut off are taken up mostly by the spleen substance. The
free nucleus likewise shares in the destruction. It is of the greatest
importance that these cells, which up to the present have not elsewhere
been described, should receive more attention. They must be of
significanc