PLATE 5 



EXPLANATION OP FIGURES 



21 A few of the liver cells from a five day culture, explant from a ten day 

 embryo, fixed in Zenker's, Bensley stain. Cell outlines, nucli, nucleoli and 

 mitochondria are shown. X 1320. 



22 Highly vacuolated liver cells, 4 day culture, explant from an 8 day embryo, 

 fixed in Zenker's, Bensley's stain. The nuclei and the nucleoli are shown, the 

 large and small vacuoles, the deeply stained mitochondria lying in the cell edges 

 and the cytoplasmic strands between the vacuoles. X 1320. 



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