484 Edwin G. Kirk. 
thelial depressions, due to irregularity in height of the epithelial 
cells, represent the beginnings of the glands, as I have satisfied 
myself by tracing, in unbroken series, all steps from the adult 
glands back to these. It will be convenient, hereafter, to refer 
to this as the intra-epithelial stage of gland formation. 
Nevertheless, itishardly possible to say that the mesoderm plays 
no part in even the initial stages, for these epithelial ridges have 
scarcely appeared before mesodermic buds begin to push up into 
them (fig. 4). These latter are constituted by local thickenings 
involving only the lam. propria, and are true mesodermic gland 
processes.> This latter condition is found rarely at 214 em. but 
often at 3 em. in the precocious regions. As soon as mesodermic 
cores appear, the basement membrane is seen to be sharper in 
outline, and more compact, beneath the pit or gland cells than 
beneath the ridge cells, being frayed out in the latter locality 
into fibres which penetrate beween the bases of the cells. Fig. 
6, indicates this same condition in a later stage. Possibly this 
has some influence on the supply of nutrition to the epithelium, 
and consequently on local differentiation of the latter(?). 
The process just described is, in essence, the same as Salvioli’s 
finding in the rabbit, but there are minor differences: 
1, In the pig the cells of elevation and depression do not 
diverge quite so widely in form, in these earliest stages. But at 
the stage represented in fig. 3 the form divergence seems quite as 
great. 
2. Inthe pig, thereis yet no differentiation, as to the cytoplasm 
into two types of cells, as Salvioli’s clear cells of the elevations, 
and granular cells of the depressions. Instead all the cells in the 
areas of gland formation, possess, as yet, a finely granular, slightly 
acidophile cytoplasm. The cells of the fundus and pylorus were 
non-granular at 2 em. but, shortly before the appearance of the 
intra-epithelial gland anlagen, have acquired the fine cytoplasmic 
granulation. 
° This term of Sewall has the priority. His gland processes undoubtedly corre- 
spond to these, and despite Ross’ criticism, certainly play an integral part in gland 
development. 
