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On the Relation of the Islets of Langerhans to the 

 alveoli of the Pancreas 



John Rennte. 



D. So. Natural History Department, University of Aberdeen. 



Of the various views which have from time to time been put 

 forward concerning the morphological and functional nature of the 

 so called Islets of Langerhans, recent investigations have brought into 

 prominence two opinions which are generally regarded as fundamentally 

 opposed to each other. On the one hand, these islets are declared, 

 chiefly on experimental grounds to constitute a tissue sui generis, by 

 Schulze [6], Helly [4\, and Tschassownikow [7]. Schulze and Tschassow- 

 nikow have independently found that as a result of occluding the 

 pancreatic ducts in mammals, degeneration of the alveoli results, while 

 the islets remain unaifected. Helly has studied their development and 

 finds that the two tissues are interdependent throughout life. The morpho- 

 logical relations as investigated by Diamare [5], in all the vertebrate 

 classes, and by Rennie [o] in Teleostean fishes, are in agreement with 

 this conclusion. On the other hand the opposite opinion, viz. that 

 these two tissues, islet and alveolus, are interdependent has been put 

 forward by several of the earlier workers, whose views are criticised 

 in detail in several of the aforesaid works. 



In recent years Dale [2], and Vincent and Thompson [8] have 

 revived the latter view in the form that the islets are modified masses 

 of ordinary secreting tissue. Dale regards them as simply a phase, 

 dependent for their existence upon the physiological condition of the 

 pancreas, and that in particular they have a function in exhaustion 

 which it is assumed is performed by internal secretion. This opinion 

 is also based on experimental results, and some of Dale's conclusions 

 may be quoted. "Change from the secreting to the islet condition is 

 greatly accelerated, both in mammals and amphibians by exhaustion 



