On the Histogenesis of Gastric Glands. 477 
investigation of the two separate problems involved: (1), from 
exactly what cells do the glands arise. (2), to what extent are irreg- 
ular growth of mesoderm and epithelium, respectively, factors. 
Compounding of the tubules is unanimously described as due to 
the upgrowth, at the bottom of the simple tubules, of partitions 
which never reach the surface. Toldt, ’81, believes that these are, 
at first, proliferating solid ridges of epithelium, later reinforced 
from below by a core of mesoderm. Sewall, ’78, Negrini, ’86, and 
Ross, ’05, hold that the upgrowths contain mesodermic cores from 
the first. According to Salvioli, 90, the process described in the 
original formation of the foveola is repeated at the bottom of the 
foveola. By mitosis, intersecting epithelial ridges arise; later 
these are reinforced from below by mesodermic cores. 
Toldt, Salvioli, Griffini and Vassale (opera cit.) also describe 
a second method of compounding by ‘‘side-buds.” Lateral 
diverticula appear, originating through local proliferation of a 
cell-group, which starts from a single parietal cell. I have con- 
firmed this for the pig (vide part IV). 
As to cytologic differentiation, Laskowsky, Sewall, Toldt, et al., 
describe an early departure of the tubule cells from the sur- 
face epithelial type, the former becoming polygonal or ovoid, 
their cytoplasm granular, and their nuclei large and vesicular. 
Toldt, ’81, Negrini, ’86, and others demonstrate that parietals 
appear in the depths of the tubules by differentiation of the em- 
bryonic tubule cells. Bensley, ’03, finds that mucus cells appear 
in the pylorus and along the lesser curve in the 6 cm. pig. Parie- 
tals appear in cardia and fundus at 7.5 em., inter-cellular duc- 
tules being present from the first. Zymogenic (serous chief) 
cells appear, at about 21 cm., at the bottom of the fundic glands. 
A few, as Sewall, ’78, and Strecker, ’08, believe in a possible meso- 
dermic origin of parietals, or of the whole gland anlagen, either 
from leucocytes or from mesodermic corpuscles, fibroblasts etc. 
III. MATERIAL AND TECHNIQUE 
The embryos were obtained in an absolutely fresh condition 
through the kindness of Swift & Company, of the Chicago Stock 
