nd when, in consequence of the increased flow, more elements are
mechanically washed out of the lymph glands. The pilocarpine
lymphocytosis does not contradict this view, for pilocarpine causes
extraordinary though transient variations in the distribution of water,
whereby the inflow into the blood of fluid containing lymph cells is
increased. We therefore regard =lymphocytosis= as the result of a
=mechanical= process; whilst =leucocytosis= is the expression of =an active
chemiotactic reaction= of the polynuclear elements.

This view finds its best support in the fact that the polynuclear
leucocytes possess lively amoeboid movement, which is completely
wanting in the lymphocytes.

Corresponding to the absence of contractility in the lymphocytes it is
also observed that in =inflammatory= processes in contradistinction to the
polynuclear neutro-and oxyphils, the lymphocytes are not able to pass
through the vessel wall. A very interesting experiment on this point was
described by Neumann years ago. Neumann produced suppuration in a
patient with lymphatic leukaemia, in whom the blood contained only a
very small number of polynuclear cells. Investigation of the pus shewed
that it consisted exclusively of polynuclear cells, and that not a
single lymphocyte had come into the exudation, although this kind of
cell was present so abundantly in the blood.

Histological examination of all fresh inflammatory processes, in which
mainly polynuclear elements are found, leads to accordant results. It is
well known that small-celled infiltration occurs in the later stage of
inflammation, apparently consisting of lymph cells; nevertheless this
does not in the least prove that these lymphocytes have emigrated here
from the blood vessels. This is not the place to enter into the very
extensive controversy on this point. We are content to refer to the most
recent very thorough paper of Ribbert. Ribbert regards these foci of
small-celled infiltration as the analogues of the lymphatic nodules, and
explains their origin by an increase in size of the foci of lymphatic
tissue, normally present, though in a condition but little developed.

It consequently follows from clinical and morphological researches, as
well as from the observations on inflammatory processes, =that the
lymphocytes are in no way connected with the polynuclear leucocytes=. We
shall reach the same result in another way in the following section.

([gamma]) The Bone-marrow.