On the Relations between the „Islets of Langerhans" etc. 83 



inanition islets transitions between the two forms of tissue are quite 

 common, and this is more noticeable than in the normal gland. The 

 reason of this is probably to be sought in the more recent formation 

 of many of these islets and a consequent less divergence from the 

 original zymogenous type. 



The appearances of transitions cannot be dismissed as adventitious. 

 No circumstances arising from obliquity of section, accident of staining, 

 or faulty fixation can be satisfactorily alleged in causation of the appearances. 



If one had begun the investigation, as we admit was the case 

 with ourselves, with a bias towards the theory that islets are organs 

 sui generis, it would be necessary to assume that these huge pale 

 islets in the inanition pancreas are not islets of Langerhans at all, 

 but new structures bearing a resemblance to them and certainly derived 

 from the secreting tubules. To uphold this view it would be necessary 

 to find structural differences between the immense inanition islets and 

 the comparatively insignificant normal islets. This we have been 

 totally unable to do. The dimensions of the different elements are 

 the same, in normal islets as in these new structures, and no differences 

 in structure can be found. 



In the face of this we consider it farfetched to assume that we 

 have to deal with two kinds of islet, and we are forced to the con- 

 clusion that during inanition large patches of secreting structure are 

 converted into tissue identical with the islets of Langerhans. 



Cat. We have to record similar, though not such pronounced 

 results in the case of the cat. 



B. Effects of Inanition npon the Avian Pancreas. 



The effects of inanition in the case of the Bird are even more 

 marked than in mammals. 



Pigeon. In the pigeon after a few days inanition we have calcu- 

 lated the ratio between the amount of leptochrome tissue in the splenic 

 end of the pancreas and that in the normal pancreas (also splenic end) 

 by drawing the islets in ten successive sections with a camera lucida 

 and cutting out and weighing the paper enclosed in the outlines. This 

 ratio is as 4,22 to 0,93 (PI. V, fig. 9, PI. V, fig. 10). 



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