On the Relation of the Islets of Langerhans to the alveoli of the Pancreas. 201 



or as Dale expresses it "reversions to an embryonic type" and that 

 a function in exhaustion is not therein proved, nor need be assumed. 

 That such changes do not invariably accompany even prolonged fasting 

 is proved in the instance quoted in a subsequent part of this paper. 

 One of the cases given by Vincent and Thompson is that of winter 

 frogs. Since hibernation is a natural phenomenon the evidence obtained 

 during this condition ought to be specially valuable, and we are 

 interested to learn that they find" in the pancreas of these animals 

 killed towards the end of the winter a marked increas in leptochrome 

 islet tissue over those killed at the beginning". If such could be found 

 to be the case generally in hibernating animals it would constitute 

 very good evidence for the argument of interchange of these tissues 

 dependent on functional state, particularly in fasting. We find that 

 earlier (1) who has made a detailed histological study of the pancreas 

 of the hibernating hedgehog has not discovered either transitional forms 

 or as far as one can judge unusual proportions of islet tissue. In one 

 instance I obtained a like negative result. To quote Carlier; in a 

 large animal in a profound state of hibernation he found that the 

 pancreas was in an "active condition and that the islets are numerous 

 though small and contain many large cells filled with fine eosinophile 

 granules", p. 344, 



In connection with this aspect of the subject we must at this 

 stage refer to a point which much to our surprise has not apparently 

 attracted the attention of other observers.^) While arguing in favour 

 of the oneness of the two tissues. Dale, and Vincent and Thompson 

 are all the time perfectly well aware that these islets are very gene- 

 rally more numerous at the splenic end of the pancreas than elsewhere. 

 In fact all of them state quite naively, that they took their material 

 for the investigation of this problem from this region, and as the 

 evidence seems to show from no other. But if it is the case that the 

 presence of islets is a question of the physiological condition of the 

 pancreas as a whole, what reason can be given for their appearing 

 more numerously at one part, and that always the same part, rather 



^) We find that Laguesse has in point of fact emphasised the existence of a 

 permanent juxta-splenic islet in Ophidians. See Vincent and Thompson, p. 90. 



