CILIATED EPITHELIUM. 69 



suffices ; the osmic acid solution should be allowed 

 to remain an hour in contact with the cells. The 

 staining fluid is replaced by water in the same way, 

 and finally, the filter-paper being removed, a small 

 drop of glycerine is applied at one border of the 

 cover-glass and gradually takes the place of the 

 water as this evaporates at the edges. In a day or 

 two the cover-glass may be fixed with chloroform 

 balsam. 



