40 



NORMAL HISTOLOGY. 



cytoplasm increases in amount, but does not suffer division, large 

 multi nucleated cells are produced, which have been called " giant- 

 cells." They occur normally in the marrow of bone and are pro- 

 duced in many of the inflammatory processes. 



The direct or amitotic method of cell-division is inaugurated by 

 an active change in the shape of the nucleus, which may have pre- 

 viously increased in size and become richer in chromoplasm. The 

 nucleus becomes constricted and finally separated into two portions, 

 which are not necessarily equally rich in chromoplasm. The cyto- 

 plasm, either at the same time or later, becomes similarly con- 

 stricted until it is divided into two parts, each containing one of 

 the nuclear divisions (Figs. 20, 21, 22). 



FTG. 20 



FIG. 21. 



FIG. 22. 



Amitotic cell-division. (Flemming.) Epithelial cells from the bladder of a salamander. 

 Figs. 20 and 21 contain nuclei with constrictions dividing them into nearly equal portions. 

 Fig. 22. Contiguous cells, each containing a nucleus about half the size of those prevailing 

 in the tissue, and, therefore, probably the result of cell-division by the direct process. 



It is believed that this mode of division does not result in the 

 formation of cells that have the complete character of the parent- 

 cell, and that their descendants form a degenerate race that is 

 destined to extinction. It is quite obvious that no such precise 

 partition of the chromatic substance is likely to take place as that 

 which is characteristic of karyokinesis, and if the chromosomes are 

 really the carriers of hereditary peculiarities, this mode of division 

 can hardly favor their perfect transmission. 



