unt. The preponderance of polynuclear and the
small number of eosinophil cells is readily explainable from the septic
infection; on the other hand the absence of granules in the mononuclear
cells is most surprising.

These two observations can only be interpreted by assuming a loss, in
certain terminal stages, on the part of the organism, of its power of
forming neutrophil substances. Similar conditions occur in non-leukaemic
conditions; for example in a striking case of posthaemorrhagic anaemia
described by Ehrlich. It is of great importance to direct attention to
these cases, which up to the present have been practically
disregarded--for ignorance of their occurrence may easily give rise to
gross errors concerning the nature and origin of the mononuclear cells,
and to the manufacture of a lienal form of leukaemia.

* * * * *

Finally we have to discuss the important question, how ~the origin of
myelaemic blood~ is to be explained. According to our conceptions two
possibilities come under consideration. Either we have to deal with a
passive inflow of bone-marrow elements, or with an active emigration
from the bone-marrow into the circulation. This important and difficult
question is certainly not fully ripe for discussion. The most weighty
objection to be raised against an active emigration of the bone-marrow
cells is derived from the behaviour of the white blood corpuscles on the
warm microscopic stage. These investigations have been performed by a
number of authors of whom may be mentioned Biesiadecki, Neumann, Hayem,
Loewit, Mayet, Gilbert, and particularly H. F. Mueller on the ground of
his summary of this subject. Concerning the behaviour of the forms of
cell here involved, all authors are agreed that under no conditions do
the lymphocytes shew the smallest spontaneous movement; whilst the
polynuclear neutrophil cells always exhibit vigorous contractility. With
regard to the forms most characteristic of leukaemic blood the statements
are partially contradictory. Some authors deny all spontaneous movement
of these cells; but most of them report observations from which it
follows that a certain power of spontaneous movement is not to be
gainsaid. It will be admitted that in questions of this kind, negative
results are weakened by positive data. Thus Jolly recently described
similar observations as follows: "C'etaient des changements de forme sur
place, lents et peu considerables, for