508 DISEASES OF THE INSULAR APPARATUS OF THE PANCREAS 



We have for this reason collected the blood of the pancreatic veins of 

 large dogs and injected subcutaneously the serum of pancreasless dogs. 

 Also in these experiments were the results negative. V. Ehrmann has carried 

 out the same sort of experiments with similar negative results. Not much 

 can be concluded from these experiments. The pancreas is extraordinarily 

 well vascularized; it may be that the amount of blood collected in a half 

 hour does not contain enough internal secretion to produce distinct evidence. 

 It should also be considered that under normal relations the blood of the pan- 

 creatic vein is carried directly to the liver, whereas in our experiments it 

 entered directly into the greater circulation. Finally we should consider 

 the possibility that the internal secretion is bound in the blood corpuscles. 

 The excellent vascularization of the pancreas may also furnish the founda- 

 tion for the fact that we have not as yet succeeded in obtaining an extract 

 of the pancreas that is active in influencing metabolism. The relations here 

 seem to be similar to those affecting the likewise well-vascularized parathy- 

 roid glands. The pancreas is also in respect to its internal secretion no stor- 

 age gland as, for example, the thyroid is. Probably the internal secretion 

 is carried off as it is formed. Zulzer, acting on similar considerations, has 

 ligated the veins of the pancreas, thus producing a stasis, and claims to have 

 seen a favorable influence of the extract obtained from such a gland on the 

 glycosuria of pancreasless dogs and on the ketonuria of human diabetes. It 

 is true that the statements of Zulzer are not very convincing. The results 

 in pancreasless dogs are very slight, and on the injection of the extracts into 

 human beings shiverings are produced that influence the metabolism in a 

 non-negligible way. 



The question as to which tissue element of the pancreas is to be referred 

 the production of the hypothetical internal secretion has, since the discovery 

 of the islands, been much discussed, especially with respect to human dia- 

 betes. I regard it as suitable to consider quite separately the results ob- 

 tained in animal experimentation, as much speaks for the assumption that 

 human diabetes is not of a single nature and as the disturbances of absorp- 

 tion, observed after shutting-off of the pancreatic juice in the animals ex- 

 perimented on seem to deviate in many respects from those in man. Soon 

 after the discovery of Langerhans' islands the view was expressed that these 

 pictures, which in their histological structure show a certain similarity to 

 certain ductless glands, especially the suprarenal cortex and the parathy- 

 roids, produce the internal secretion of the pancreas, while the glandular 

 parenchyma is concerned exclusively with the production of the external 

 secretion. The view that was later upheld by several authors, namely, that 

 the Langerhans' islands could pass over into glandular parenchyma, or 

 reversely; I have mentioned this in speaking of the anatomy and embryology 

 of the pancreas; in which exposition, in consideration of all the data as to 

 the histological and embryological observations, I have accepted the views 



