394 SUMMARY OF CURRENT RESEARCHES RELATING TO 



nuclei and also an increase in the diffuse stainablc substance. (4) From 

 a diffuse staining of the nuclei degeneration cannot be directly inferred, 

 and especially not in the sense tbat the form in question owes its origin 

 to a degeneration. (5) The succession of tbe various phases of division 

 is in fragmentation very frequently by no means regular. Nuclei and 

 cells may persist for long in one stage. The occurrence of polynuclear 

 and of united cells is thus intelligible. 



B. (1) From larger and smaller wandering cells polynuclear ele- 

 ments may arise by fragmentation, without any division of the cellular 

 body at first occurring. (2) In such processes very complex nuclear 

 figures are at times formed, and the nucleus is sometimes simply con- 

 stricted. (3) An increase in the chromatic substance was frequently, 

 but not constantly observed. (4) Observation of living objects shows 

 that from giant-cells nucleated elements may be given off, sometimes in 

 the form of processes, sometimes simply peripherally. 



C. (1) That wandering cells may divide according to the ordinary 

 type of mitosis is very probable, but not certain. Division by fragmen- 

 tation is, on the other hand, very frequent. (2) The discovery of mitosis 

 in the elements of the blood, lymph, and lymphatic organs cannot be 

 held as a proof that the lymphocytes usually divide in this fashion, far 

 less that they do so exclusively. Deductions from these elements to 

 wandering cells, and vice versa, are not directly admissible, since the 

 two kinds of cells are not homologous, and may in different conditions 

 divide differently. (3) Polynuclear cells arise on the plates usually by 

 fragmentation, much less frequently by mitosis. The two processes 

 must not, however, be too rigidly separated, nor must the difference be 

 minimized, for in fragmentation the typical disposition of chromatic 

 filaments is different, the relation of the nuclear membrane is different, 

 the contour is usually sharp, &c. 



D. The nuclear degeneration is next discussed. This may take 

 three forms — (1) simple disappearance of nucleus, without disorder of 

 chromatic substance ; (2) nuclear degeneration, in which disorder of the 

 chromatin precedes disappearance ; (3) degeneration of the figures of 

 division or abortive division. 



E. Progressive changes are next described. Whether the wandering 

 cells finding their way into the tissue may break up, or remain and pass 

 through progressive changes, is undecided. It is yet more doubtful 

 whether they play a part in the development of the granular and con- 

 nective tissue, for instance of the vessels. That progressive metamor- 

 phosis is impossible must not be concluded, since many of the experi- 

 mental conditions were not favourable to such changes. The cells which 

 were allowed to grow on the above-mentioned plates (on the mesentery), 

 united together in continuous layers, and became flat, with dull proto- 

 plasm and vesicular nucleus. So in plates placed in the lynrph-sacs, it 

 seemed almost demonstrable that the cells changed within the recesses 

 of the plate. The cells in the meshes became epithelioid and giant cells, 

 before the development of tissue and vessels proceeding from the walls 

 of the lymph-sacs had penetrated the most external layer of the lymph 

 thrombus. The epithelioid and giant cells may persist for long as such 

 before the above-mentioned development reaches the surface of the 

 plates. As to the share of the epithelioid and giant cells in the forma- 

 tion of connective tissue, no conclusion was arrived at. In the thrombus 

 at a later stage the epithelioid cells could not be distinguished from the 



