Joseph Marshall Flint ~ 437 
cells have increased in size, but otherwise their character is not altered. 
The parietal cells, however, are wedge-shaped and already begin to have 
some of the typical appearances of the demilune. ‘Throughout the 
serics of embryos there is a considerable variation in the alveoli of the 
same gland, but the series of illustrations represents, however, the aver- 
age condition found in the alveoli at the ages mentioned. In the adult 
submaxillary of a pig (Fig. 14) stained by Mallory’s method, there is 
a marked difference in the microchemical] reactions of the two classes, 
of alveolar cells. The mucous cells have increased greatly in size, the 
Fra. 12. Fia. 13. Fia. 14. 
Fig. 12. Terminal alveolus from the submaxillary gland of pig’s embryo 18 centi- 
meters long. Hardened in Zenker’s fluid and stained by Mallory’s method. x 650 
diameters. Mucous cells have now in places reached the basement membrane. 
Parietal cells are pushed off into the spaces left between the cells of the former group. 
Fig. 13. Terminal alveolus from submaxillary gland of pig two days old. Hard- 
ened in Zenker’s fluid and stained by Mallory’s method. x 650 diameters. The 
mucous cells have in most cases reached the basement membrane. Parietal cells are 
now found here and there between them, already giving.the final and definite rela- 
tions of the demilunes of Gianuzzi. 
Fic. 14. ‘Terminal alveolus of submaxillary gland of adult pig, showing the final 
form and arrangement of the demilunes. Hardened in Zenker’s fluid and stained by 
Mallory’s method. X 650 diameters. The differences in the staining reactions be- 
tween the cells of the central and parietal groups are indicated. 
mucous globules are slightly larger, and give the body of the cell a 
clearer, more glairy appearance, while the nucleus still retains its cres- 
centic shape and is pushed off to the pole of the cell nearest the mem- 
brana propria. Much more marked changes have occurred in the parie- 
tal cells; the cytoplasm has taken on a distinct bluish tinge and is now 
very granular, while the nuclei are less vesicular but are still brightly 
stained with the orange element of the dye. 
Ever since the demilunes were first described by Gianuzzi they and 
their functions and relations have been the subject of an extensive dis- 
cussion in the literature. Stohr, who believed that the demilunes are 
30 
