RESEARCHES ON KARYOKINESIS AND CELL DIVISION. 45 



series of changes. The resting nucleus enclosed by a 

 membrane was invisible^ but nuclei about to divide con- 

 tained granules and threads which assumed the characteristic 

 forms. 



Division of Nuclei into more than two parts. — Several ob- 

 servers have described cases of the karyokinetic division 

 of nuclei into more than two parts. -Eberth^ studied indirect 

 division in tissues which were in process of regeneration 

 after artificial injury. He either cut with a scalpel or 

 destroyed with chloride of zinc portions of the epithelium 

 of the cornea, and of Descemet's membrane in the rabbit 

 and the frog, then, after some days, made chloride of gold 

 preparations from the injured parts. He believed that some 

 of the appearances he saw were due to the simultaneous 

 division of a nucleus into several parts. The four young 

 nuclei, which he figures lying close together and apparently 

 of the same age, may have all proceeded from a single 

 mother nucleus, but there is little reason to suppose that 

 the nucleus he describes with seven pointed processes (fig. 

 32) was preparing to divide into seven parts. 



More detailed evidence has been brought forward by 

 Julius Arnold," whose preparations were from examples 

 of epithelioma, carcinoma, and sarcoma of the human 

 subject. He describes nuclei with three and four processes 

 (figs. 20 and 21) which have a distinct membrane, the 

 interior being filled with short rods thickened at one end. 

 The character of these is very abnormal. More convincing 

 are other figures he gives of spherical nuclei with a distinct 

 membrane, and containing a triradiate arrangement of 

 granules in double rows ; from the granules pale striae pass 

 towards three foci or poles (figs. 25 and 26). 



Dr. Louis Waldstein was kind enough, at the request of 

 Prof. Lankester, to show me his preparations from tumours 

 of the same kind as those which Arnold used.- In these 

 triradiate figures were to be found similar to those described 

 by Arnold. Their appearance is shown in fig. fS9. The 

 rays of the figure did not consist of double rows of granules, 

 but indications of fine fibrils proceeding towards three poles 

 were visible. I saw no membrane around nuclei in this 

 state. From the appearance of these triradiate forms it 

 seems probable that in the figures of Arnold, which I have 

 copied in figs. 20 and 21, only the chromatic part of the 

 nucleus is represented corresponding to the granules in figs. 

 25 and 26. 



1 ' Virchow's Arcliiv,' Bd. 67, 1876. 



2 Ibid., Bd. 78, 1879. 



