EPITHELIAL MOVEMENT 563 



as spider web, glass wool, asbestos, etc., when it is brought into 

 contact with them. 



The cell movement on the glass and celloidin film is very 

 vigorous, sometimes more rapid than on the endothelial surface. 

 In the movement on such supports chemotactic influences are to 

 be considered as excluded. 



It has been repeatedly observed by various writers that a suit- 

 able support for the growing cells is an important requisite; 

 Harrison ('14) demonstrated lately the importance of such fac- 

 tors for the movement of embryonic cells very clearly. The facts 

 above described confirm this view, that stereotropism plays an 

 important role in cell movement. 



The behavior of corneal epithelium in vitro serves to throw 

 some light on the mechanism of epithelial growth in vivo. 



The experiments show clearly that the epithelium is able to 

 extend from the cut end quite rapidly in sheets into the medium 

 (plasma) , or on the tissue (plasma and serum) , and can cover a 

 large area, whereas mitotic cell divisions are not necessary at all. 



That Oppel ('12) as well as Osowski ('14) did not observe 

 amoeboid activity of the epithelium was perhaps due to the diffi- 

 culty of direct observation. Special, careful observation on the 

 movement of epithelium of warm-blooded animals, however, is 

 necessary. 



In conclusion, I wish to express my indebtedness to Prof. 

 R. G. Harrison for his direction and valuable advice. 



