ider more closely the share
which the various regions of the haematopoietic system take in the
formation of the blood, and especially of the colourless elements.

[alpha]. The Spleen.

The question whether the ~spleen~ produces white blood corpuscles has
played a large part from the earliest times of haematology.

Endeavours were first made to investigate the participation of the
spleen in the formation of the white blood corpuscles by counting the
white corpuscles in the afferent and efferent vessels of the spleen. It
was thought that the blood-forming power of the spleen was proved by the
larger number of corpuscles in the vein as compared with the artery. The
results of these enumerations however are very varying; the
investigators who found a relative increase in the vein are opposed by
other investigators equally reliable; and with the experience of the
present day one would not lay any value on these experiments.

We must emphasise the fact, established by later researches, that after
extirpation of the spleen, an enlargement of various lymphatic glands
occurs. The alterations of the thyroid, which have been observed by many
authors, cannot be described as constant.

Further, the blood investigations which Mosler, Robin, Winogradow,
Zersas and others have carried on in animals and man after removal of
the spleen must here be mentioned. These have already proved that a
leucocytosis occurs after some considerable time. Prof. Kurloff carried
out detailed investigations in 1888 in Ehrlich's laboratory, and
carefully studied the condition of the blood after extirpation of the
spleen. As the work of Prof. Kurloff has so far only appeared in
Russian, his important results may be here recorded more fully. For his
researches, Kurloff employed the guinea-pig, as this animal by its
peculiar blood is specially suited for this purpose.

In order to give a systematic account of the results of these
important investigations, we must first shortly sketch the
normal histology of the blood of the guinea-pig according to
Kurloff.

In the blood of the healthy guinea-pig the following elements
are found.

I. Cells bearing granules.

1. =Polynuclear, with pseudoeosinophil granulation.= This
granulation, which Ehrlich had previously found in the rabbit,
is easily distinguishable from the true eosinophil, since it is
much finer, and stains quite differently in
eo