1*11 



The or^anisMtion ol llu' (■|)itlu'lial cells. cullixaU'd in 

 vilro occurs when Uie growlli of llie ciilliire lor oik; or 

 another reason suffei's and becomes irregular. It may be 

 the result, when the I issue is nol properly placed in the 



Fig. 42. 

 Experiment 1476. 22nd. passage of a 48 hour old pure culture of epithe- 

 lium from the iris of the chicken embryos. The photograph is taken of a 

 section through the culture and the keratinization can be seen. 

 From The Journ. of Exp. Med., 1924, XXXIX, 585. 



medium. — or more so even when the central portion of the 

 tissue becomes thick and more or less necrotic, because il 

 is poorly supplied with oxygen and nourishment. 



