670 
MR. J. 1ST. LANGLEY ON THE HISTOLOGY AND 
diminution in the size of the granules is very marked in cells in which the outer zone 
takes up the larger part of the cell. After great activity there is also an obvious 
diminution in the size of the cells, and although it is difficult to be certain of the 
changes which take place in the first stages of activity, I have little doubt that the 
diminution in the size of the cell begins with the development of the clear outer zone. 
In specimens treated with osmic acid there is another effect of activity to be seen, 
viz. : the cell-substance stains more deeply than during rest. In the oesophageal 
glands the tint of staining is not in so constant a relation to the amount of secretion 
jnoduced as in some other glands, the extent to which the tint deepens seems to vary 
as the stimulation is produced by digestible food or by mechanical stimulation. These 
and some other apparent causes of variation have not been closely determined, but the 
main fact of an increase in the depth of staining has always been obvious. 
It was stated by Sewall and myself"’ that absolute alcohol added to the fresh 
teased-out gland altered the normal appearances; and I have said above that the 
granules are in part dissolved. Nevertheless, alcohol specimens of oesophageal glands 
taken during digestion show the two zones in the gland-cells ; the non-granular zone 
stains with carmine, and thus specimens can be obtained (Plate 77, fig. 8), which, 
except for the smaller size of the cells, closely resemble similarly prepared specimens of 
the pancreas. It is almost unnecessary to remark that the “granules” of the inner 
zone in alcohol specimens are not the granules present in the fresh gland. With Zeiss’, 
oc. 2, obj. E or F, the granular zone appears as a fine network. 
Nothing very definite can be said as to the time after feeding at which the changes 
in the oesophageal glands occur. When Frogs are taken as nearly as possible alike, and 
they are treated in the same way, then the results obtained correspond very closely, 
but when such results are compared with those obtained from Frogs at a different 
season of the year, with those obtained from Frogs which are older or younger, more 
or less healthy, or when different amounts of food are given, then considerable 
divergences occur. 
The changes occurring are in each case of the same nature, but the extent to which 
these changes take place varies largely. Hence any estimation made of the time 
taken for the first appearance of a clear zone, for its maximum development, and so on, 
can only be approximate. 
During the first hour or hour and a half after feeding, no distinct change is to be 
seen. After this period a diminution in the number of the granules in the outer half 
of the cell becomes obvious. Usually this is first seen in the glands close to the 
stomach. The disappearance of granules in the outer portion of the cell goes on, so 
that a clear zone is formed. The clear zone steadily increases until the sixth to 
twelfth hour, or even later, the time varying with the state of the animal and the 
amount of food given. The glands then begin to become more granular; the time of 
complete recovery varies enormously ; in some cases the glands are throughout granular 
* Op. cit., p. 283. 
