KAETOKINESIS 



51 



ing been made by the cells. In the case of the connective tissues, 

 it has a more important function than the cells; while the amount 

 of intercellular substance in epithelial structures is trifling. 



CELL -DIVISION 



The increase in the number of cells in the body may be accom- 

 plished in two ways: 



a. By direct division. 



b. By indirect division. 



Direct division is a process in which the cell becomes con- 

 stricted and a portion of it separated from the remainder. It is 



FIG. 28. INDIRECT CELL-DIVISION AFTER FLEMMING. 



now believed that in most instances the separation of the proto- 

 plasm is preceded by a series of changes in the nucleus. This mode 

 of division is called indirect. The changes in the nucleus go by 

 the name of karyokinesis, or mitosis. 



KARYOKINESIS 



The reticulum of fibers already mentioned as traversing the 

 substance of the nucleus has an affinity for nuclear stains, and 

 its substance is therefore called chromatin. During karyokinesis 

 the chromatin of the nucleus undergoes a series of complicated 

 changes, resulting in its division into two equal parts. This is 

 followed by the division of the rest of the cell. During the process 

 the chromatin presents figures of great variety and intricacy. 



