84 Swale Vincent and F. D. Thompson. 



In the newly tormed islets may frequently be seen masses and 

 columns different from those constituting the greater part of the islet 

 (PI. V, fig. 11, /.). In a specimen stained with haematoxylin and 

 eosin, they stand out as reddish purple columns staining with some- 

 thing approaching the intensity of the zymogenous tissue, but more 

 homogeneously, giving the impression ot a pencil drawing softened 

 by stumping (PL V, fig. 11). These we have so far not found in the 

 normal pancreas, but it is probable that they are present, and cor- 

 respond to what has been described in fishes by Diamare, Rennie, 

 and others. The cells composing these darker islet columns have 

 somewhat the same arrangement as those forming the bathyclirome 

 columns (cf. PL V, fig. 11 with PL IV, fig. 7) without, however, tlie 

 same chromogenic capacity, 



C. Effects of Tuauitiou upon the Ampbibian Pancreas. 



Under this head our results entirely confirm those of Dale. We 

 have worked exclusively with winter frogs and we find in the pancreas 

 of those animals killed towards the end of the winter a marked in- 

 crease in leptochrome islet tissue over those killed at the beginning.^) 



How are we to account for the effects of inanition upon the amount 

 of the leptochrome tissue? Or rather, why are the effects of inanition 

 identical with those of exhaustion of the gland? Ä x>riorl one might 

 anticipate that the effects of withholding food would be the opposite 

 of those induced by extreme secretion of the pancreatic juice. Thus, 

 one might expect that since the normal stimulus to the flow of secretion 



') A veiy interesting misinterpretation of our results which occurred last 

 winter, will help to confirm the actual facts of the case. We obtain our frogs from 

 the Physiological Laboratory of the University of Minnesota, and a stock was taken 

 in at the beginning of the winter. After a few weeks the pancreas from one of 

 these frogs was exaniiiied, and tlie slide labelled „inanition", and compared several 

 months later with timi oC :i froi.' of a fresh batch imiiorted from Minneapolis. Tliis 

 slide was labelled ^.pain.rc.a.s, frcsli IVog". We were astonished to find that what 

 we called the fresh pancreas coiitninrd miicli iikhc leptochrome tissue than the 

 „inanition'' dih'. lint on cmpiiry of the Lahoratory Attendant at Miniiea[)olis we 

 cleared up lln' (jiiticulty. lie ke|it the frogs all the winter in the laboratory in 

 iiiniiiii;.' vMitii- and wiiliout Inixl, mid tlic IVo;,' nl' the second hatch which uc had 

 labelled „fresh", had in icuiity liccii wilhnul loud ^jeveral nmnths longer than the 

 one we labelled „inanition". 



