a considerable increase in
four days of the mast cells in the irritated portions of the skin.

[30] That a well-marked basophil leucocytosis has not so far been
observed may be thus explained. The substances which attract the mast
cells are very rarely produced in the body; much more seldom than the
corresponding substances attractive for the eosinophils. In morbid
conditions, where substances attracting the mast cells were present, it
might be possible to find a suppuration of mast cells, or a mast cell
leucocytosis as well. In this connection an observation of Albert
Neisser is of the greatest interest. He met with (private communication)
one, out of numberless cases of gonorrhoea, in which the purulent
secretion consisted entirely of mast cells.

[31] Unger has recently published completely analogous observations on
the human breast for the mast cells. Under the influence of stagnation
of the milk he saw an invasion of the gland tissue by typical mast
cells.

[32] A very interesting observation of Goldmann's deserves mention here.
Goldmann found in preparations of the pancreas of proteus sanguineus,
containing parasites, that the eosinophil cells in the neighbourhood of
the encapsuled parasites were much increased, whereas they were sought
for in vain, in more distant parts.

[33] A case observed some time back by Ehrlich may here be mentioned as
a characteristic example. A woman received a blow in the region of the
spleen by a fall from the roof, which gradually led to a marked splenic
enlargement. As no other symptoms appeared, the surgeon in charge
proposed splenectomy, on the assumption of a pure splenic leukaemia.
Examination of the blood, however, shewed a condition fully
corresponding with myelogenic leukaemia, and thus prevented surgical
interference.

[34] Ehrlich was once able to recognise, by balancing the different
forms of cells, the blood preparations after the loss of their labels
from some ten cases of leukaemia.

[35] Literature given by A. Fraenkel.

V. DIMINUTION OF THE WHITE BLOOD CORPUSCLES (LEUKOPENIA).

Diminution of the white blood corpuscles plays--comparatively with their
increase--a very unimportant _role_ in clinical observations. It occurs
in but few groups of diseases, and but seldom attains a marked degree.
Koblanck has described a most marked fall in the number of the
colourless cells, in the following remarkable blood condition. In a
strong man, 25 years of age, whos