486 Edwin G. Kirk. 
time of the appearance of the mesoblastic reinforcements to the 
20-26. em. stage, but all this time there is a very gradual increase 
in height of intervening ridges, until finally at 24-28 cm. the defini- 
tive condition is reached, in which there are no longer any 
papilliform elevations, all the ridges having grown up to the 
same height as the papillae. 
The nodal papillae are often expanded or club-shaped at the 
top, resembling greatly intestinal villi, but of course shorter. By 
reference to fig. 7B, it will be seen that in any section through the 
mucosa the elevations and depressions must necessarily present 
great irregularities, as e. g., the epithelial line may dip into a 
gland pit, then perhaps ascend to the top of a nodal elevation, 
then descend to the level of an interglandular ridge. 
Moreover, these ridges and pits cannot be interpreted as mere 
folds of the mucosa, having no permanent significance, nor any 
relationship to the adult gland. Once established, these pits 
indeed deepen and compound at the bottom, many of them even 
divide into two glands; but their continuity with the adult gland 
is established by unbroken series. Moreover, we shall see that 
soon after this formation, certain cells in their depths differentiate 
into recognizable elements of the adult gland. Finally, the meso- 
blastic cores of the ridges are, as shown, true thickenings of the 
lamina propria, not mere foldings of a |. p. of uniform thickness. 
It is now easy to understand the many contradictory accounts 
of the nature of the primary gland processes. Brandt described 
papille or ville, which later fuse at their bases. Sewall, Salvioli 
and many others described only the interlacing ridges, and failed 
to explain the very frequent appearance of villoid cross sections. 
As growth proceeds, all the epithelial cells increase in absolute 
size. Those on the ridges become very high, inverted pyramidal 
in shape, the proximal part being compressed into a narrow, caudal 
process, which attaches to the basement membrane (figs. 6 and 
11). The nuclei are elongated and laterally compressed. The 
cells in the pits, or embryonic gland cells® increase in breadth, but 
° T retain Sewall’s term, as it has priority, and is self-explanatory. Toldt calls 
these “‘adelomorphs,”’ but applies this term at a later stage to the mucus and ser- 
ous chief cells, 
