EPITHELIAL MOVEMENT 549 



of strands or sheets of cells into isolated masses was of frequent 

 occurrence. The number of round cells increased rapidly from 

 day to day, and generally fat droplets grew in number and size 

 with the age of the culture, until the cells were often literally 

 packed with them. No marked increase of mitotic figures was 

 seen. 



The activity of cell movement into the plasma depends on the 

 consistency of the latter. Around the explanted tissue, lique- 

 faction and retraction of the plasma were often observed which 

 caused changes of the arrangement of cells. 



»»■.♦* 





%---*.- 



ed 



Fig. 2 Vertical section of corneal tissue cultivated in ])lasma. Experiment 

 XXXVIII, 5, showing the epithelial movement {E) along the endothelial surface 

 {ed). Age of the culture, four days. Drawn from one of the serial sections. 

 \(. cut ends; ep, epithelial, cd, endothelial surface; c, part of connective tissue of 

 coi-n€^,^X 98. 



h. Movement on tissue. The next important type of the epi- 

 thelial movement is that on the corneal tissue. By virtue of 

 this, the growing epithelium spreads over the edges of the frag- 

 ment and along the endothelial surface. Figure 2 shows an ex- 

 ample of this very clearly. A movement of this type occurred 

 in some cases on all edges of a fragment and in others only on a 

 part of it, combined with other types. It was also observed that 

 part of the cut end of the epithelium might remain almost inac- 

 tive, while in the other part marked activity occurred. 



c. Other types of movement. Whenever the growing epithelial 

 cells came into contact with the cover-glass, they moved actively 

 over it. The character of cell movement, however, was essen- 



