EPITHELL\L MOVEMENT 555 



II. ON THE REACTION OF EPITHELIAL CELLS TO CERTAIN SOLID 



SUPPORTS 



1. Movement on flat surfaces 



a. On glass and celloidin. We shall first consider movement 

 on the glass cover-slip. ^ There is difficulty by means of usual 

 culture method in bringing the epithelial rim into contact with 

 the co\'er-glass from the beginning. Attempts to do this by 

 reducing the plasma failed, as the epithelium did not show activ- 

 ity unless the medium was used in sufficient quantities. 



In the later experiments, the piece of cornea (cut ofT tangentially 

 to eyeball) was placed on the cover-slip, mainly with the inner 

 surface down, and subjected to slight pressure by means of thin 

 silver wires or glasses and kept in that position for a certain 

 period after mounting with serum, so that the cut ends came into 

 contact with the glass. When the silver wires were properly 

 placed and controlled under the microscope, it was possible in 

 almost every instance to bring certain parts of the moving epi- 

 thelium into contact with the cover. Of course, where even a 

 minimal space existed between the tissue and cover-glass surface, 

 the epithelium crept on the underlying tissue. 



Cover-slips coated with celloidin were also used. Thus the 

 movement of the epithelium on celloidin and glass surfaces, 

 respectively, could be compared. A comparison could also be 

 made in the same preparation, by employing a cover-slip, only 

 one half of which was coated with celloidin. Such preparations 

 must be handled carefully, otherwise a change of cell form readily 

 occurs. 



No characteristic difference whatever in the mode of movement 

 on the two different surfaces could be noticed. If the epithelium 

 grew out vigorously, closely attached to the cover-slip, each cell 

 became flattened into an exceedingly thin layer. In some 

 instances it was seen that the advancing border became verj^ 



1 It should be stated here that the cover-glasses used in these experiments were 

 through!}' cleaned and washed in the vapor of distilled water, as is usually done 

 to remove any trace of alkali, in order to exclude anj' chemical influence from that 

 source. (Ostwald-Ruther, Physiko-chemische Untersuchungen.) 



