362 ADOLPH R. RINGOEN 
F. Histology of the fully differentiated gastric gland 
Figure 7 (embryo 146 mm. long) represents the fully differen- 
tiated gastric gland. In specimens of this length the vast 
majority of glands present such an appearance, although there 
may be slight variations in the length of the neck and in the 
size of the fundic portion. These slight variations are, however, 
of no fundamental importance, for they do not signify that the 
glands differ in character. 
All of the gastric glands are unbranched, flask-shape struc- 
tures. Never have I been able to find the bifurcated forms 
described by Peterson(’09). He believes that the neck cells 
of the gland are of a rather primitive character during their 
early history, and that they may give origin to a side bud 
which with further differentiation, gives to the gland a forked 
appearance. 
At no time have I been able to distinguish more than one 
type of cell in a gland (fig. 7). All authors who have investigated 
the gland cells of lower vertebrates are quite agreed in the 
occurrence of a single cell-type.* According to Edinger (’77), 
in the fishes, this single type is homologous neither to the chief 
nor to the parietal cell of the mammalian stomach. His con- 
clusion has been generally accepted. It appears from the in- 
vestigations of numerous other observers that the differentiation 
of two the cell-types in the gastric glands of fishes does not 
obtain. This specialization probably appears phylogenetcally 
much later. 
As far as Squalus acanthias is concerned, and as Peterson 
(09) maintains for a number of selachians, the neck cells of 
a gastric gland are not concerned in the formation of any specific 
secretion. This activity appears to be confined to the cells mak- 
ing up the fundic portion of the gland. In all the cases that 
have come under my observation, I have found that the secre- 
tion granules are elaborated exclusively in these cells. As to 
the precise character of these granules, I have no definite 
knowledge. 
3 Oppel (96) agrees with Edinger in the finding of only one type of cell in 
the glands of fishes, but states that this single type appears to possess relation- 
ships with the parietal cell of mammals. 
