26 



GENERAL ANATOMY OF THE TISSUES. 



which sometimes lie quite free, and sometimes are wholly or 



Fi 6 partially included 



in the parent cells 

 of the second gene- 

 ration; or a more 

 free development of 

 a secondary cell 

 within a parent cell 

 occurs, from which 

 cell - development 

 then takes place in 

 one mode or in the 

 other. 



In connection 

 with the process of 

 endogenous cell-de- 

 velopment, we may 

 very properly speak 

 of the formation of 

 a great number of 

 nuclei within cells, 

 a process which is 

 frequently the pre- 

 cursor of cell-deve- 

 lopment, but which may also continue alone. Even in 

 the common endogenous cell-development (and also in the 

 cleavage process) we not unfrequently observe three and 

 four nuclei in a parent cell, so that then, instead of two 

 secondary cells, many arise at once, e. g. in the hepatic cells 

 of embryos. In certain animals (Cucullanus, Ascaris dentata, 

 Distoma, Cestoidea), instead of cleavage-masses, nuclei alone are 

 developed in the first stages of development, and it is only 

 later, when by successive endogenous multiplication these have 

 increased to a great bulk, that they become surrounded by 



Fig. 6. Cartilage cells from a fibrous, velvety, articular cartilage of the condyle of 

 the femur of man, x 350, all lying in a fibrous matrix, and readily isolated : a, simple 

 cells, with or without a thickened wall, with 1 or 2 nuclei ; b, secondary cells, or 

 cells of the first generation, with 1 or 2 nuclei; 1, 2 — o, or more, in parent cells; 

 b', c, cells of the second generation, 1 — 3 in number, in cells of the first; rf, freed 

 groups of secondary cells. 



