264 SKIN, HAIE, AND NAILS, BY ALFRED BIESIADECKI. 



In the fourth month we find, intercalated between the 

 above, from three to four tiers of flat, nucleated, very sharply 

 defined cells that correspond to the nail cells. 



The portion of skin enclosed by this wall, which subse- 

 quently becomes the bed of the nail, differs at this time in no 

 respect from the rest of the skin. At the fifth month the 

 above-described nail cells introduce themselves between the 

 mucous and horny layer of the nail bed, so that the previously 

 formed nail is still covered by the horny layer, and has no 

 free border. 



As the nail extends below the horny layer to the tip of the 

 finger in the sixth month, it raises the horny layer in the 

 form of a pocket open behind. 



