434 INTERNAL SECRETION 



ministration of carbohydrates in large quantities. According to 

 Lewaschew and Pischinger, the islands are really acini in a state 

 of functional exhaustion which, after a period of rest, resume 

 their secretory activity. 



Laguesse (1893) was the first to adopt the view that the 

 internal secretion is elaborated by the cells of the islands of 

 Langerhans, the islands thus possessing an endocrinal function 

 which is of importance in the metabolism of the carbohydrates, 

 while the external digestive secretion is supplied by the acini. 

 The supposition is that a continuous transformation of acini into 

 islands, and vice versa, takes place, by which the two secretory 

 processes are carried out. Laguesse's theory principally depends 

 upon the presence of transition forms ; these he described with 

 extreme minuteness and his findings are confirmed by a large 

 number of observers (Mankowski, Gentes, Perdrigeat and Tri- 

 boudeau, Dale, Vincent and Thompson, Marrassini). Changes 

 in the number and size of the islands, and transition forms be- 

 tween acini and islands and vice versa, have been obtained by 

 certain experimental measures, such as the injection of secretine, 

 pilocarpine and phlorizin ; fasting ; and over-feeding. But these 

 transformatory changes of acini into islands and vice versa have 

 been questioned by several authors, first by Vassale, then by 

 Diamare, Stangl, Rennie, and others, and more recently by 

 Weichselbaum and Kyrle. 



In his critical survey, Lombroso arrived at the conclusion 

 that the morphological findings, obtained from experimental and 

 comparative anatomical investigation, were insufficient to justify 

 the theory of mutual transformation. According to Lombroso, 

 mutual transformation does not prove a sharp differentiation of 

 the internal and external secretions as functions of the two pan- 

 creatic tissues, acini and islands; but it confirms his view that 

 both functions of the pancreas are undertaken by both tissues. 



There are numerous authors, however (Kohn, Massari, Dia- 

 mare, Rennie, Opie, &c.) who deny Laguesse's theory of the 

 intimate morphological relationship between the acini and the 

 islands of Langerhans ; who regard the latter as independent 

 tissue formations, but believe them to be ductless glands epithe- 

 lial organs analogous to the parathyroids, the suprarenal cortex, 

 and the anterior lobe of the hypophysis and whose property it 

 is to elaborate the pancreatic hormone. 



Within the last fifteen years, clinical diabetes has provided a 

 certain amount of anatomico-pathological material, which has a 

 considerable bearing upon the internal secretory elements in the 

 pancreas. 



The numerous investigations which have been made have 

 led, however, to very divergent results. The findings which they 

 observed led a number of investigators to adopt the insular theory 

 (Opie, Ssobolew, Herzog, Weichselbaum and Stangl, Sauerbeck, 



