96 Swale Vincent and F. D. Thompson, 



2. In birds, reptiles and amphibians in addition to the lepto- 

 chrome islets, there appear to be solid masses of cells of a diiferent 

 character. These stain very deeply with most ordinary staining 

 reagents and are specially marked after fixing with Flehiming's fluid. 

 They constitute the bathychrome tissue in these animals. 



3. The bathychrome tissue has a tendency to form in certain 

 regions a true syncytium. 



4. In birds, reptiles, amphibians, and fishes as well as in mam- 

 mals there are individual bathychrome cells scattered throughout the 

 zymogenous tissue in various regions of the gland. ^) 



5. In all the chief groups of vertebrates the leptochrome islets 

 (the known islets of Langerhans) frequently show distinct traces of an 

 alveolar arrangement. The solid columns composing the islet often 

 show, for example a double row of nuclei corresponding to the position 

 of the nuclei in the secreting tubules. 



6. The islet columns are frequently in complete anatomical con- 

 tinuity with the surrounding zymogenous tubules, and all kinds of 

 transition forms are common throughout vertebrates. 



7. In reptiles and fishes a distinct lumen, within the leptochrome 

 islet aiea can sometimes be detected. 



8. In mammals (dogs and cats), birds (pigeons) and amphibians 

 (frogs) the effect of inanition is to markedly increase the amount of 

 the leptochrome islet tissue, at the expense of the zymogenous tissue. 

 In this condition direct continuity and transition forms are even more 

 marked than in the normal animal. 



9. If, after a period of inanition, an animal be restored to its 

 noimal condition of nutrition, the pancreas likewise returns to the 

 normal, and the presumption is that alveoli are reconstructed from 

 islets. 



10. An increase in the amount of islet tissue may be induced 

 by exhausting the pancreas with sccictiii (Confirmatory of Dale). 



11. Ill tjie leptochrome islets of the pigeon after inanition and 

 in llie conespoiiding strnctines in tclcostean lishes, we have soiiie- 



'j See A|i|)('ii(lix. 



