548 SHINICHI MATSUMOTO 



a. Movevient in the medium. When a culture of cornea, freshly 

 prepared in vitro, was examined under the microscope, the edges 

 of the piece were seen to be sharply defined. One or two hours 

 later the epithelium on the cut ends gave the impression of be- 

 coming a little translucent and swollen, a narrow clear rim ap- 

 pearing along the edges. Here and there, around the edges of 

 the fragment, isolated round epithelial cells were to be seen, 

 singly or in groups, having been detached by mechanical injury 

 during the operation. 



There was a short latent period before any movement was 

 noticed, the first cellular activity appearing between the third and 

 tenth hours. Accordingly, examination after twelve to twenty- 

 four hours showed an active outgrowth of epithelial cells present- 

 ing amoeboid processes. As a rule, the corneal epithelium showed 

 characteristic sheet-like extension during the period of active 

 movement; the advancing edge was always furnished with an 

 amoeboid border of hyaline ectoplasma, as has been described by 

 Harrison ('10), Carrel and Burrows ('11), Lambert and Hanes 

 ('13) and Holmes ('14). Some of the epithelium exhibited marked 

 motility, recalling the movements of amoeba, so that an exact 

 camera-lucida drawing could not be made; pseudopodia were 

 formed, and through their activity the cells changed shape or 

 moved from place to place. Some of the cells which showed 

 filiform processes were over 0.2 mm. in length. 



The strong tendency of the cells to lateral spreading brought 

 about the formation of a continuous membrane, extending nearly 

 horizontally, usually slanting upward a little toward the end. 

 The spreading membrane also changed its direction of move- 

 ment, showing contraction under various circumstances. Growth 

 in strands was also observed. The growing epithelium, usually 

 two cells in thickness, sometimes covered an area a little larger 

 than the original corneal piece, whereby the cells became flattened 

 and the intercellular spaces grew wider. 



There was apparently little growth after the third (sometimes 

 the fourth) day. The tissue itself then gave the impression of 

 being less compact and more translucent than formerly. The 

 epithelial cells showed a tendency to round off. The rupture 



