436 INTERNAL SECRETION 



results. The method was based upon the known fact that ligature 

 of the excretory ducts of the pancreas, and the injection of foreign 

 substances into them, suppresses the external secretion and may 

 lead to more or less pronounced atrophy of those portions of the 

 gland by which the external secretion is elaborated. It was soon 

 found that glycosuria did not, as a rule, make its appearance in 

 experiments of this sort, and that the tissue of the islands of 

 Langerhans remained in comparatively good condition. After 

 ligature of the excretory ducts of the pancreas of guinea-pigs, 

 Schultze observed disappearance of the acini, with persistence of 

 the islands and absence of glycosuria ; similar findings were 

 described by Ssobolew in rabbits, dogs and cats ; and by Laguesse 

 in rabbits. Sauerbeck observed transient glycosuria in rabbits 

 after ligature of the pancreatic duct ; but the incidence, course 

 and intensity of the glycosuria was said to run parallel with 

 changes in the islands of Langerhans. Tiberti describes similar 

 findings, while different results were obtained by other observers 

 (Hansemann, Mankowski) who employed the same method. 



From the results of his own experiments and those of other 

 scientists, Lombroso concluded that, after ligature of the pan- 

 creatic duct of rabbits, changes take place in the acini, but that 

 the acini do not entirely disappear, and that the islands also 

 undergo modification, though more slowly. Glycosuria is either 

 absent, or occurs in isolated instances only. He ascribes a par- 

 ticular significance to the fact that the resorption of nutriment 

 remains unchanged. 



In pigeons, ligature of the excretory ducts produced changes 

 in the pancreas similar to those observed in rabbits ; but though 

 glycosuria was not present, the birds died after two to three 

 weeks, in consequence of the derangement of the absorption of 

 food. It must be rememberecL, however, that the absence of 

 glycosuria in birds is no proof of the continuance of the hormone 

 production ; the diabetic disturbance of metabolism which follows 

 extirpation of the pancreas is expressed only by hyperglycasmia, 

 though Lombroso failed to take this fact into consideration. 



The numerous and very careful experiments which have been 

 carried out with the pancreas of dogs all show that, not only do 

 the acini not disappear after ligature or resection of the excretory 

 ducts, but that they do not undergo appreciable change. Lom- 

 broso found perfectly preserved normal acini fourteen days after 

 operation. This finding has been explained by the presence of 

 supernumerary excretory ducts, by which the passage of secretion 

 from the gland was facilitated (Hess and Sinn). Lombroso re- 

 jects this explanation, however, and he emphasizes the fact that 

 well-developed acini were present in implanted portions of 

 pancreas which sufficed to prevent the occurrence of diabetes. 



A consideration of all the available experimental material 

 led Lombroso to conclude that both the epithelial tissues of the 



