arrow. These proliferative processes may give rise to a
considerable enlargement, for example, of the spleen, without any change
in the specific character of the leukaemia, or the condition of the
blood. In spite of the splenic tumour we have to deal then with a pure
lymphatic leukaemia. In customary clinical language, a case of this kind
would be described as lieno-lymphatic leukaemia. The unreliability and
incorrectness of this terminology is best illustrated by another form of
leukaemic metastasis. In lymphatic leukaemia the liver may swell by
lymphomatous growth, to a large tumour, and we ought then to speak of a
"hepato-lymphatic" form of leukaemia. This term is by no means so
misleading as lieno-lymphatic; for no one would conclude from the former
that any liver-cells passed into the blood, whilst the latter implies
the idea, that specific splenic cells take part in the blood changes.

Further, the assumption of a pure =lienal= variety of leukaemia is totally
unwarranted from haematological investigations. The possibility of a
specific blood change, depending solely upon disease of the spleen,
appears _a priori_ almost excluded, after what has been said on the
physiological participation of the spleen in the formation of the blood.

Pathological data completely confirm this view. Ehrlich at least, in an
enormous number of cases, has never once succeeded in confirming the
existence of a purely splenic form from the blood examination[33].

The conditions in myelogenic leukaemia are quite similar, for foci of
myeloid tissue may appear in the spleen or lymph glands according to the
kind of metastasis. As it is the proliferation of the myeloid tissue and
not the accompanying swelling of spleen or lymph glands that is specific
in the process, the nomenclature "lienomedullary or medullary-lymphatic"
leukaemia must also be described as illogical and misleading.

We distinguish then, from the histological standpoint, but two forms of
leukaemia:

1. =leukaemic processes with proliferation of lymphoid tissue=:

"~lymphatic leukaemia~";

2. =leukaemic processes with proliferation of myeloid tissue=:

"~myelogenic leukaemia~."

The accompanying clinical phenomena may be indicated by simple
unequivocal amplifications, for instance, "lymphatic leukaemia with
enlargement of the spleen or of the liver"; "myelogenic leukaemia with
enlargement of the lymph glands," &c.

From our present knowledge, which, it may b