PLATE 3 



EXPLANATION OF FIGURES 



8 Two liver colls on the third duy of cultivation, explant from a nine day 

 embryo. Showing differences in mitochondrial content in cells side bj'' side. 

 X 750. 



9a-96 Two views of a liver cell on the third day of cultivation, explant from 

 a seven day embryo. X 750. 



9a kShowing cell outlines, nucleus, nucleolus, mitochondria and ten colorless 

 cytoplasmic granules (black in figure). 



96 The same cell after the addition of neutral red. A few more granules 

 were visible stained a deep yellow-red. At X an irregular vacuole also stained, 

 from which stretch out neutral red canals; these were continually retracted, and 

 extended, the two pointing toward the base of the cell being particularly active. 



10 A liver cell on the fifth day of cultivation, explant from a nine day em- 

 bryo, stained with neutral red. Showing cell outlines, position of nucleus, mito- 

 chondria, granules (black in figure), and vacuoles (dotted circles), some of the 

 latter containing granules. X 750. 



11 A liver cell with neutral red added to the medium at the time of observa- 

 tion; five day culture, explant from a seven day embryo; showing nucleus, nucleo- 

 lus, granules and vacuoles. Two of the granules are large, the others small; a 

 few lie within one of the vacuoles. The two large vacuoles in this cell changed 

 form continually. The mitochondria have not been drawn. X 750. 



12a-12b Two liver cells or cell-groups on the fifth day of cultivation, explant 

 from a nine day embryo, stained with janus green and neutral red, and showing 

 nuclei, nucleoli, mitochondria, neutral red granules and fat. In each group 

 there are three nuclei, no cell boundaries visible between them. In cell a no 

 neutral red granules were visible; in cell b there were 4 granules in one part of the 

 cell. There are three nucleoli in one nucleus of cell b. X 750. 



13 A liver cell on the fifth day of cultivation, explant from a six day em- 

 bryo; neutral red added to medium at time of planting. Showing nucleus with 

 three nucleoli, two fat globules, mitochondria, four scattered neutral red gran- 

 ules and two groups of granules, one small and one large. X 750. 



14 A liver cell on the second day of cultivation, explant from an eight day 

 embryo; trypan blue added to medium at the time of planting; showing nucleus 

 with two nucleoli, two fat globules and many trypan blue granules. X 750. 



15 Portion of a liver cell membrane on the third day of cultivation, explant 

 from a 16 day embryo; edge of explant indicated by heavy line; cells at edge of 

 explant in dotted lines. Many fat globules, most of them free in the culture 

 medium derived from the explant. X 312. 



16 A group of four liver cells on the seventh day of cultivation, explant from 

 a sixteen day embryo, showing cell outlines, nuclei, two nucleoli, and intracellular 

 fat globules. The fat globules are numerous and large, approaching the nuclei 

 in size. X 750. 



17a-176 Two liver cells on the niutli day of cultivation, explant from an 

 8 day embryo; trypan blue in the medium. X 750. 



{Conlinucd on page 306) 



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