436 RAYMOND M. SELLE 
of the process of cornification. The former of these were the cells 
which were cast off and furnished the cells found in a sample 
taken during this stage. They are called superficial epithelial 
cells for the reason that they were above a region in which corni- 
fication later took place. The cornifying process began rather 
suddenly and continued at a rapid rate simultaneously through- 
out the entire vagina. It began two to four cells below the sur- 
face of the superficial epithelium, and involved four to six cell 
layers. In some eases it extended up into the superficial epithe- 
lial cells before the latter had been entirely cast off. This is 
shown in figure 4. Beneath the stratum cornium may be dis- 
tinguished the typical layers of stratified epithelium. 
A little later in this stage the leucocytes had entirely disap- 
peared from the vaginal fluid and the only cells found in the 
lumen were the superficial epithelial cells. As a result of the 
sloughing off of these cells, the vaginal mucosa became reduced 
in height and the cornified layer exposed. 
It usually happened that the shedding of these superficial 
epithelial cells occurred while the entrance to the vagina was 
closed by the vaginal closure membrane described by Stockard 
and Papanicolaou, often making it necessary to break the mem- 
brane in order to get a sample. 
Stage 2. Cornified cells only 
(Stockard and Papanicolaou’s stage 1) 
A vaginal sample taken during this stage contained many 
flattened, horny, non-nucleated or cornified cells. No leucocytes 
were found in the lumen. Stockard and Papanicolaou in their 
first paper mentioned two kinds of cornified cells. These are 
apparently two different stages of the same process of cornifica- 
tion. The various intermediate degrees of cornification can be 
demonstrated both in smears and sections counterstained with 
eosin, the amount of stain taken by the cells varying with the 
extent of cornification. 
Because of the fact that there were almost always a number of 
cornified cells at the external orifice of the vagina, smears of the 
