On the Relations between the „Islets of Langevhans" etc. 99 



have produced the result. But even if this last were the case, then 

 the appearances would correspond with some chemical differences in 

 the darkly-staining tissue. Again, we have failed to conceive how the 

 appearances described and depicted can be due to any fallacy arising 

 from the direction of the section through different alveoli. 



The appearance we have described as a syncytium is at first sight, 

 very suggestive of faulty fixation, but it has occurred in specimens 

 placed while living in a saturated solution of corrosive sublimate or 

 in strong Flemming's fluid. 



The „bathychrome" granules appear in some cases to have the 

 same staining reactions as the zymogenous, so that it may be suggested 

 that the „bathychrome" tissue is simply over-loaded zymogenous tissue, 

 standing out in marked contrast in stained preparations to the „lepto- 

 chrome" tissue which is fully exhausted glandular tissue. The whole 

 matter is however very doubtful and difficult to interpret. It is remo- 

 tely possible that in some cases we have encountered pathological 

 conditions. 



The fact that the darkly-staining tissue does not occur in mam- 

 mals (for we now think that the example depicted in the ox is capable 

 of another explanation) and is shown most typically in birds and rep- 

 tiles, combined with its non-occurrence in other secreting glands, in- 

 duces us to believe that it corresponds to some structural or physio- 

 logical peculiarity in certain portions of the pancreas. The tissue is 

 moreover sometimes easily seen to differ in form and structure from 

 the ordinary zymogenous tissue. 



