36 THE GENERAL CHARACTERS OF CELLS, BY S. STRICKER. 



to proceed, not only from fission of old nuclei, but from the 

 growth of entirely new ones. 



Development of nuclei proceeds in a manner essentially 

 similar to that of cells when they undergo complete division. 



As an example of endogenous cell multiplication, that which 

 takes place in the eggs of insects may, according to Weismann,* 

 be adduced ; but whether the formation of pus corpuscles in 

 epithelia (Buhl)-f- is to be regarded as an example of this mode, 

 or of division (Remak) is at present doubtful. 



If the entire mass of proloplasm contained within a mem- 

 brane or capsule divides into two or more segments, we can no 

 longer regard this as an endogenous mode of cell division, 

 but as cell genesis by fission. Cartilage cells and the first 

 two segmentation spheroids may be adduced as examples. 



When a naked mass of protoplasm divides, the act is obvi- 

 ously to be regarded as one of fission. As an example of this 

 the fission of the eggs in the ovaries of young cats may be 

 adduced (Pfliiger). 



In multiplication by gemmation a little elevation first pro- 

 jects from the cell a bud which is subsequently separated by 

 constriction of its base. An example may be seen in the pro- 

 pagation of the yeast fungus, in the development of the egg in 

 Nematoids (Meissner), as well as in the budding of the germ of 

 many holoblastic eggs (Salmofario, Strieker). The detach- 

 ment of a cell from the maternal structures is a phenomenon of 

 movement (Max Schultze). In regard to cell formation by 

 fission, it has been ascertained that the protoplasm becomes 

 partially contracted in the fashion of an hour-glass. The depth 

 of the constriction continuously increasing until at length the 

 protoplasm is divided into two segments. The whole process 



* Entwickelung der Dipteren, 1864. 



t The author of this paper has, as yet, had no opportunity to examine 

 critically the communications made by Volkmann and Steudener, respect- 

 ing the migrations of amoeboid eel's into epithelial cells, and the illusory 

 appearances wh r ch may have ltd to the statement that an endogenous 

 formation of cells take place in epithelial cells. He, however, fully miin- 

 tains the correctness of the statements of Buhl in regard to the develop- 

 ment of cells from pre-existent epithelial cells, and has consequently 

 adduced it as an instance. 



