40 SHINICHI MATSUMOTO 



Cultivated in vitro, the corneal epithelium, when .stained with 

 neutral red, showed a condition entirely similar to that seen in 

 unstained preparations. The cells exhibited practically the same 

 degree of activity, though at times they degenerated a little 

 earlier than in the control preparation. 



By this method, the cell movement along the tissue, which took 

 place, as a rule in the fluid or semifluid culture medium, could 

 be easily detected. That the spreading epitheUum was, as a rule, 

 two and sometimes three layers thick, was clearly demonstrated 

 (fig. 2, a), while in an unstained preparation it was rather hard 

 to determine whether they were one or two cells in thickness. 



As the epithelium spread out and the individual cells became 

 very flat and thin, a change in the arrangement of the granules 

 took place. Then the granules of the basal cells, which were 

 rather irregularly distributed at first, frequently assumed a cres- 

 cent-shaped arrangement (fig. 2, a). If the staining was light, 

 the tiniest red granules in the cells of the surface layer became 

 faint relatively ea^'lier. As a rule, the hyalin processes of the 

 cells on the border did not exhibit any red granules. In general, 

 after all activity of cells ceased, the red granules faded out and 

 fatty granules increased, whereas the nucleus remained unstained. 

 The same was true of the isolated epitheUal cell. 



So far as our observations go, there was in general a direct 

 relation between the cell activity and presence of neutral red 

 granules, although of course the intensity or richness of the gran- 

 ules^was not always parallel with the cell activity. 



b^ Some other dyes. In the corneal epithelium subjected to 

 'Nile blue sulphate,' the granules were beautifully stained. This 

 dye was found, however, to be injurious to the cells, and even 

 the solution 1 : 200,000 in most instances caused more or less 

 injury to the epithelium, though not enough to interfere immedi- 

 ately with the cell activity, since in many cases the cells contin- 

 ued to move. Disintegration of cells took place earlier, and a 

 preparation which showed intense granulation never Hved so long 

 as the control culture (unstained or stained with neutral red). 

 In addition to this, in the preparation subjected to the dye, fine 

 violet crystals appeared in the cells or in the medium. Nile blue, 



