STUDIES ON THE PANCREAS OF THE GUINEA PIG 387 



intralobular islets are related to the ducts. If islets are originat- 

 ing throughout life from the ducts and if the intralobular islets 

 are in direct continuity with the ducts as Laguesse and I have 

 shown, is it not probable that the intralobular islets originate in 

 the same way as the interlobular ones, namely from the duct 

 epithelium? If this be true, then the islets would of necessity 

 occur in the interior of the lobules, where the ducts from which 

 they have arisen are located. 



I am accordingly of the opinion that the normal regulation of 

 islet content in the pancreas is by interstitial growth of pre- 

 existing islets, and by the formation of new islets from the duct 

 epithelium, and not at all by the formation of new islets out of 

 acini. 



This conclusion is in accord wdth the observations of Helly 

 ('06) and Weichselbaum and Kyrle ('09) on the origin of the islets, 

 and with the experimental work of Kyrle ('08) on the regulatory 

 processes in the pancreas after resection of a portion of its 

 substance. 



BIBLIOGRAPHY 



For a full list of references on the structure of the pancreas the reader is referred 

 to the general summary of Laguesse, E., in Revue d'histologie generale, vol. 2, 

 1906-1908, Paris. 

 Altmann, R. 1894 Die Elementarorganismen und ihre Beziehungen zu de 



Zellen, zweite Auflage, Leipzig. 

 Babkin, B. p., Rubaschkin, W. J., Ssawitsch, W. W. 1909 Ueber die morph- 



ologischen Veranderungen der Pankreaszellen unter der Einwirkung 



verschiedenartiger Reize. Arch. f. mikr. Anat., Bd. 74. 

 Bayliss, W. M., and Starling, E. H. 1903 On the uniformity of the pancreatic 



mechanism in vertebrata. J. physiol., Lond., vol. 29. 

 Bensley, R. R. 1910 On the nature of the canalicular apparatus of animal cells. 



Biological Bulletin, vol. 19. 

 Dale, H. H. 1905 On the 'islets of Langerhans' in the pancreas. Phil. Trans. 



Roy. Soc. London, vol. 197, Series B. 

 Dewitt, L. M. 1906 Morphology and physiology of areas of Langerhans in some 



vertebrates. J. Exper. Med., vol. 8. 

 DiAMARE, V. 1899 Studii comparativi sulle isole di Langerhans del pancreas. 



Internat. Monatsch. f. Anat. etc., tome 16. 

 GiANELLi, L. 1898 Ricerche macroscopiche e microscopiche sul pancreas. 



Atti della R. Accademia dei Fisiocritici, s6rie 4, vol. 10. 



