[VINCENT & THOMPSON] THE ISLETS OF LANGERHANS 285 
cance of the appearances described. We have at the present time little 
to add to the discussion of the subject there offered. In elasmobranch 
fishes the same dark columns and patches are strikingly visible, but 
do not present any features which throw light on their actual nature. 
The inconstancy of the “bathychrome ” appearance in birds sug- 
gested that this might be due to differing physiological conditions. We 
therefore considered it necessary to re-investigate-the effects of inanition 
in the pigeon, and we have found, speaking generally, that the appear- 
ences we have described as “‘ bathychrome” are more common in this 
condition than in the normal bird. Incidentally, too, this has enabled 
us to confirm, in the case of the pigeon, our previous observations as 
to the effects of inanition in the direction of increase of the islets of 
Langerhans, and to add to them the statement that this increase is most 
marked in a region near the posterior end of the dorsal pancreas. 
The most striking difference between our sections of inanition and 
normal gland is that in the normal the alveoli are plump and are dis- 
tinctly seen to be separated from each other by lavers of connective 
tissue; whereas in the pancreas, after inanition, the alveoli are less 
distinctly outlined, the whole picture is blurred, and all the elements 
faintly stained. 
In many regions there is no distinct increase in the islet tissue 
(meaning by this typical islet of Langerhans), but in the gland, after 
inanition, is seen a curious blotchy or mottled appearance. This is 
due to the fact that some parts of the tissue have lost their staining 
power to a greater extent than others. It has occurred to us that these 
are an expression of the same changes as result in the formation of new 
islets. The lighter patches seem to have become more definite as we 
proceed from ventral to dorsal pancreas, and from anterior to posterior 
end of the gland, until in the region near the posterior end of the dorsal 
pancreas the pale patches are represented by large definite islets of 
Langerhans. These islets give abundant evidence of their relation to 
the zymogenous tissue and all forms of transitions are common. 
