Ill 



and 18 hours al'lerwards an extensive uniform growth has 

 taken phice around the okl piece. In cultivating the epi- 

 thelial cells on the free surface of the clot, I obtained large 



Fig. 10. 



Stained culture of epithelial cells, 6 weeks old. Shows the epithelial pavement 



formation; mitosis may be seen. X about 660. 



From The Journ. of Exp. Med. 1922, XXXV, 367. 



cultures which easily could be multiplied and what was 

 still more important, 1 was alDle to keep the cells growing 



