678 
MR, J. N. LANGLEY ON THE HISTOLOGY AND 
of appearing homogeneous, shows a network with inter-fibrillar substance. The inter- 
fibrillar substance takes the form of granules. In sections cut the clay after the tissue 
has been placed in alcohol, the granules are only slightly stained, but if the tissue be 
left in alcohol for several weeks before sections are made, the granules then stain 
deeply and are very distinct (Plate 77, fig. 4). The network with its contained 
granules makes its first appearance at the junction of the protoplasmic and muci- 
genous portions of the cells (see Plate 78, fig. 1), and as secretion goes on encroaches 
more and more on the mucigen. A similar network is seen during digestion in the 
cylindrical cells of the surface of the mucous membrane, but it is usually confined to 
the junction of the protoplasm of the cell with the mucigen. 
The changes which take place in these cells differ somewhat, but not essentially, 
from the changes which take place during secretion in the mucous salivary glands 
of Mammals. The protoplasm around the nucleus and the protoplasmic network 
throughout the cell grow ; the growth is more rapid in the peripheral protoplasm. 
It is not quite clear, however, why the inter-fibrillar substance increases in power of 
staining with osmic acid. 
We have seen that during fasting the granules in the pepsin-forming cells slowly 
diminish, in the distinct mucin-forming cells the amount of mucigen goes on increasing 
for some time after the granules of the pepsin-forming cells have begun to decrease. 
The maximum amount of mucigen is contained by the pyloric and similar gland-cells 
after a moderately prolonged fast. The minimum amount of mucigen is contained by 
these cells twelve to eighteen hours after a heavy meal; it is then only with difficulty 
that the mucous can be distinguished from the sub-cubical cells. 
Similar changes to those above described are seen in the stomach of a Frog one to 
two days after feeding with sponge; the main difference is that the tint of staining is 
usually lighter than after feeding with worm or other digestible substance. 
It is worth remark that although the mucous cells of the necks of the glands in 
alcohol specimens closely resemble the mucous cells of such glands as the sub-maxillary 
of the Dog, yet in fresh specimens they differ in one important respect. In the sub¬ 
maxillary gland of the Dog the cells are in life densely crowded with distinct granules, 
whilst the mucous cells of the stomach and, generally speaking, of the alimentary 
canal are transparent and show no trace of granules. 
The Pepsin-content of the (Esophageal and Gastric Glands. 
Swiecicki concluded from his observations that the oesophageal glands are at any 
rate the chief source of pepsin, and that the gastric glands produce little, perhaps 
indeed none.* 
* He says: “ Alle diese Thatsachen spi’echen hiernacli dafiir dass bei den Froscben die Pepsinbildung 
vorzugsweise, ja vielleicht nur allein in dem GEsophagus von statten geht, wahrend der die Belegzelleu 
fiihrende Magen die Saiire bildet ” (s. 452). 
