On the Relations between the „Islets of Langerhans^ etc. 93 



and the „solid", it may be that the more solid type with its absence 

 of definite alveolar form and its dark closely packed nuclei, really 

 represents a degenerated islet (cf. PI. IV, Fig. 1, PI. IV, Fig. 2). 



It was stated on a, previous page (p. 27) that if a pancreas 

 from an animal in inanition were examined, a very remarkable increase 

 in islet tissue would be noted; but that if after such a period, the 

 animal were restored to its normal state of nutrition, the usual pro- 

 portion of islet tissue would be found. The most obvious explanation 

 of this, and the one provisionally adopted in a former section of this 

 paper, is that the alveoli are reformed from the islet tissue. There is, 

 however, another possibility, viz. that the islet formed from alveoli 

 as a result of changed physiological conditions is never reconverted 

 into secreting tubules, but having reached the last stage in its career, 

 degenerates and disappears. If this be the case we must suppose that 

 new alveoli are formed from the existing tubules and occupy the space 

 recently occupied by islet. On this hypothesis the more sohd islets above 

 referred to might possibly be regarded as nothing more than worn out 

 alveoli about to disappear. Of the two possible views here put for- 

 ward, we are inclined to support the former. 



Experiments involving ligature of the pancreatic duct have given 

 in the hands of various observers contradictory results, but we think 

 the balance of evidence derived from this line of investigation is in 

 favour of the view that „islet" is not a separate and distinct kind of 

 tissue from „alveolus". According to Ssobolew^) and Schultze^) ligature 

 of the duct is followed by a complete atrophy of the pancreatic cells 

 proper, while those of the islets of Langerhans are not affected, and 

 these statements have been urged in favour of the view that the islets 

 are functional entities independent of the zymogenous tissue. But other 

 observers, notably Mankowsky^) and Dale*) deny that the islets in 

 the pancreas show any special immunity from the destructive effects 

 of the operation, though Laguesse believes that many islets under these 



') Virch. Arch. Bel. 168. S. 91. 1902. 



-) Arch. f. mikr. Anat. Bd. 56. S. 491. 1900. 



^) Loc. cit. 



•*) Loc. cit. 



