118 



growth and migration of epilhclial cells seem to be much, 

 more dependenl upon the mechanical condition than those 

 of fibrol)hisls. Leo L o c b "4) has already pointed out 

 years ago. that the epithelium follows the way of least 

 resistance. 



Fig. 15. 



18th passage of a pure culture of epithelium 48 hours old, from the iris 



of the chicken embryos. The new growth is found as rudimentary tubules. 



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



When growth occurs in membrane formation, it is rapid 

 and extensive; when the tubular type results, the rate of 

 growth is markedly slower and the actual increase in mass 



