PLATE 1 



EXPLANATION OF FIGURES 



1(7-1/ Six views of a culture, explant from a 16 day embryo. No growth on 

 the third day. X 37. 



la Fourth day of cultivation; 12.00 Noon. Explant and four small groups of 

 migrated liver cells. 



1/* Fifth day of cultivation; 10.30 a.m. Growth membrane of considerable 

 size around almost the entire edge of the explant. Fifteen wandering cells have 

 migrated out from the explant. 



Ic Fifth day of cultivation; 3.00 p.m. The growth membrane has changed 

 in shape but has not appreciably increased in size. Outlines of a few cells and 

 their nuclei are shown; fourteen wandering cells present. 



Id Sixth day of cultivation; 11 a.m. The growth membrane had become 

 much more ragged and fenestrated. 



le Sixth day of cultivation; 4 P.M. One isolated group of liver cells. Four- 

 teen wandering cells. 



1/ Eighth day of cultivation. The growth membrane is very much broken 

 up; many isolated cells and many dead cells. 



2a-2h Eight views of a cell on the fourth day of cultivation, explant from 

 a nine day embryo, showing the rapid and extensive changes in form of a large 

 vacuole containing granules. The small spherical vacuoles did not change 

 shape. Views 2a-2e are of the unstained cell; 2/, of the cell stained wath janus 

 green; 2h, of the cell after neutral red staining. X 750. 



2a 3.34 P.M. Showing cell outlines, nucleus, nucleolus, the fat globule, a 

 few of the mitochondria, and the vacuoles, some of them containing granules. 

 X750. 



26 3.40 P.M. All of the mitochondria are shown here. 



2c 3.47 P.M. 



2d 3.58 P.M. The vacuole has broken up into two smaller vacuoles, each 

 containing granules. 



2e 4.05 P.M. The two vacuoles have united. 



2/ 4.20 P.M. Janus green added. The culture contracted with a conse- 

 quent decrease in extent of area of cell, nucleus and vacuole. None of the 

 smaller vacuoles are to be seen. Another cell has grown out behind the original 

 cell. 



2g 4.21 P.M. 



2/t 4.29 P.M. ^fter neutral red has been added to the culture. A third cell 

 has begun to grow out and in the three cells numerous granules free in the cyto- 

 plasm, which were not before observed, are now visible. 



300 



