LIVER CELLS FROM CHICK EMBBYO 285 



embryos of thirteen to sixteen days' incubation. Of these 23 

 (70 per cent) gave some hver-cell growth, but in none was it very 

 extensive. Two series with a total of 12 cultures were made from 

 seventeen to eighteen day embryos. In these no liver-cell growth 

 was obtained. 



Size of explant. The length and width of fifty-one explants were 

 measured and their areas roughly computed. The explants 

 varied in area from approximately 300 to 12,000 square fx. No 

 correlation was found between the area of the explant and suc- 

 cessful growth; good growths occurred from explants of all sizes. 



Cell division 



Although endothelial cells divided actively in many of the 

 cultures, no division of liver cells was observed. In the living 

 cultures and on the fixed slides they frequently showed elongated 

 nuclei and nucleoli, and one amitotic division of the nucleus 

 without subsequent division of the cytoplasm was observed in a 

 living culture. Many liver cells of the living cultures and of the 

 fixed preparations contained two and sometimes three or four 

 nuclei. 



General cell characters 



The liver cells in that part of the growth membrane near the 

 explant were thick, polygonal, and opaque, having a greenish- 

 gray color due to the dense packing of their cytoplasm with 

 mitochondria. The marginal cells and the cells entirely isolated 

 from the explant were flattened and much clearer than the other 

 liver cells, but were never as clear as the endothelium. Their 

 processes, although quite short, were usually free of mitochondria 

 as were also the free edges of the cell (figs. 2, 8, 9, 10, 12, 22, 

 24, 25). In most of the cells ectoplasm and endoplasm could 

 be distinguished. In the endoplasm were seen the nucleus, the 

 mitochondria, bile granules, neutral red granules, and fat glob- 

 ules, all closely packed together and showing only slight shifting 

 movements. In the ectoplasm there were usually some neutral 

 red granules, and here they were very active, even large ones 

 moving about to a considerable degree. 



