672 
MR. J. N. LANGLEY ON THE HISTOLOGY AND 
If at any time the sponge is vomited by the Frog, or if the sponge be removed, the 
glands begin at once, or almost at once, to return to the normal state; and in one 
to two days the lumen is no longer visible, and the cells are crowded with large 
granules. 
We know from the experiments of Heidenhain that in Mammals the mechanical 
stimulation of one part of the stomach causes only a temporary secretion from the 
glands of other parts. In the Frog the case is different, the mechanical stimulation of 
the stomach causes a considerable secretion from the oesophageal glands—a secretion 
which lasts several days at least, 
On some Disputed Points in the Histology of the (Esophageal Glands. 
In the account of the changes in the oesophageal glands given by Sewall and myself 
there were two points which clashed with the earlier observations which Nussbaum 
made on osmic acid specimens. He described the gland-cells of the normal hungry 
Frog as having a large clear zone, and found that on feeding the animal the granules 
increased so that in three to five hours a clear zone was no longer to be seen. 
Grutzner’s* results suggest an explanation of the divergence between the account 
of Nussbaum and that of Sewall and myself. He finds that in the normally hungry 
Frog the oesophageal glands are granular throughout and diminish in granularity 
during digestion ; but finds also that if a Frog is kept longer than usual without 
food a clear zone is then formed in the oesophageal glands and that on feeding 
there is at first an increase of granules. Thus according to Grutzner, Nltssbaum’s 
results would represent what occurs in a pathological and not what occurs in a normal 
condition. 
During the last year and a half I have made a considerable number of observations 
with the view of determining the points at issue. As regards the state of the glands 
in the normal hungry Frog I have seen no reason to alter my first-formed opinion. 
In some Frogs a large clear zone in the oesophageal glands does occur, namely, in 
those in which there are signs of general inflammation. In nearly all cases in which 
I have found a marked clear zone in the gland-cells of a hungry Frog, the animal had 
some mark or other of an ill state of health. I have frequently selected lively, active 
Frogs, and sluggish, unhealthy ones from a batch brought to the laboratory, and in 
a few days examined the oesophageal glands. The gland-cells in the former w r ere 
granular throughout ; those of the latter had almost always a clear zone. 
There is one condition in which I have found apparently healthy summer Frogs, 
kept without food for three or four days, show a clear zone in the oesophageal glands, 
viz.: when they have remaining in the stomach some piece of stick or leaf, or other 
undigested substance ; such undigested material causes a continuous secretion from 
the oesophageal glands (see action of sponge, p. 671). 
* Grutzner, Pfluger’s Arch., Bd. xx., s. 395, 1879. 
