THE METABOLISM OF CARBOHYDRATES 807 



the liver and inhibit the sugar production in this organ. A very small 

 portion of the pancreas is sufficient for this purpose, but we have been 

 unable to imitate the action of the pancreas still in vascular connection 

 with the body by injection or administration of extracts of this organ. 

 Even connection of a healthy animal with a diabetic animal by means 

 of its blood-vessels, so as to allow the healthy blood, presumably provided 

 with the products of secretion of the pancreas, to circulate through the 

 diabetic animal, does not abolish the condition of hyperglycsemia in the 

 latter, though connection of the portal vein of the healthy animal with that 

 A B 



a* - f ; A 



**.*' ., -. ^" ffy * B ^-* 



f **' J~*L* '^" * 7 C? ?V r f 'j '"V. 



IfSli^x *f'5%|^H- : 



* % *-' " \ ,*'v,,. . * s* ' '^ ; .., 



FIG. 356. (A) and (B) show an islet with the surrounding tissue in a resting gland (A) 

 and after exhaustion with secretin (B). In (A) the secreting acini are charged with 

 symogen granules. In (B) these have entirely disappeared. On the other hand no 

 change is noticeable in the cells of the islet. In the latter the granular cells are the 

 6 cells, and the clear hyaline cells are the a cells, (m) showing what are called 

 Minkowski granules. The granulation of this cell is regarded by Bensley as due to 

 postmortem changes. 



of the diabetic animal has, according to Hedon, had the effect of stopping 

 the condition of glycosuria. Further work is required on this point. 



We thus see that the pancreas has a two-fold function, namely, the 

 secretion of a digestive juice into the intestine and the exercise by some 

 means or other of an influence on general metabolism, the absence of 

 which is followed by the supervention of diabetes. Corresponding with 

 this two-fold function, two kinds of structures are present in the gland, 

 the secreting acini and the islets of Langerhans. These latter, though 

 arising in connection with the ducts, are solid masses of cells and have no 

 communication with the lumen of the ducts. According to Bensley and Lane 

 the islet cells may be divided into two varieties which have been given the 

 name of A and B cells, according as their granules are fixed respectively 

 by alcoholic or watery solutions. It has been shown both by Bensley and 

 by Homans that these cells undergo no alterations when the gland is excited 

 to secrete by the injection of secretin. On the other hand, if four-fifths 



