KARYOKINESIS AND ITS RELATION TO FERTILIZATION. 195 
tologie,’ 1884, iii, No. 1) describes the occurrence of karyo- 
kinesis in pathological processes of cell-formation. 
This is the place to speak of the peculiar, and in many 
respects abnormal, form of karyokinesis which is met with in 
wandering cells, and in the so-called giant-cells of the marrow. 
The wandering cells and all their kin, which we will include in 
the name “lymphoid cells,’ appeared for a long time not to 
undergo karyokinesis. Thanks chiefly to the careful researches 
of Flemming (1. c.) and his pupils, we have to look upon this 
important and peculiar group of cells as behaving, in this 
respect, in the same way as other cells. Nevertheless in these 
cells direct nuclear division is always frequent, and the want 
of perfect agreement among writers on the subject leads to 
the supposition that there are a number of different forms or 
subforms of lymphoid cells, which may behave very differ- 
ently in regard to the phenomena of division. 
We know, as examples of lymphoid cells, the wandering 
cells in connective tissue, colourless blood-corpuscles, 
of which again various subforms must be distinguished (cf. the 
work of Ehrlich and his pupil Einhorn, especially the dis- 
sertations of the latter, ‘ Ueber das Verhalten der Lymphocyten 
zu den weissen Blutk6rperchen,’ Berlin, 1884), viz. the round- 
cells of lymphatic glands and the spleen, the thy mus-cells as 
they develop post-embryonically in this at first epithelium-lined 
organ, and the marrow-cells. It is by no means quite clear 
how all these various forms of cells are related to one another. 
Lowit (127) and J. Arnold (4) especially point out that the 
nature of the lymphoid cells, in which mitosis has been studied, 
has not been established with that certainty which is desirable. 
It is possible, for instance, that in the colourless cells observed 
in the blood undergoing mitotic division, one is dealing, not 
with true wandering cells, but with the early stages of red 
blood-corpuscles, or with loosened endothelial cells engaged 
in mitosis. It is certain that mitosis has been observed in 
the colourless cells circulating in the blood, by J. Arnold (4), 
Peremeschko, Flemming, Lavdowsky (1238), Bizzozeri, Kults- 
chitzky, by the latter in the new-born dog (‘ Centralbt. f. d. 
