THE SPLENO-PANCREATIC INTERNAL SECRETION. 



405 



oxidizing substance, insures functional metabolism of loth gland- 

 ular structures present, the lolular acini and their immanent 

 structures, the islands of Langerhans, which metabolism, during 

 the passive, or inactive, state of the organ, ends in the formation of 

 the secretion granules. 



5. When at the end of the fourth hour of general digestion the 

 pancreatic ferments are required in the intestinal canal, the vagus 

 incites, sustains, and governs the functional activity of loth the 

 pancreas and the spleen, and thus insures their synchronous action 

 as long as the pancreatic ferments are needed. 



6. Intrinsic-nerve constriction of the arterioles that supply 

 loth the pancreatic lolules and the islands of Langerhans with cap- 

 illaries constitutes, as elsewhere, the mechanism through which 

 glandular activity is sustained; lut, the islands' vascular ampullce 

 possessing no muscular layer, they lecome the seat, owing to their 

 large size, of sufficient Hood-pressure to cause the Hood-plasma and 

 its contained splenic ferment and oxidizing substance to filtrate 

 through their walls. 



7. Some lolules are entirely composed of true secreting cells; 

 others contain, lesides, islands of Langerhans. In the latter lol- 

 ules the secretion, therefore, consists of two different lodies: the 

 granules of the true secreting cells and the Hood-plasma derived ly 

 filtration from the islands. 



8. The true secreting cells and those of the island "being in 

 continuity and surrounding a common lumen (Opie), loth lodies 

 (1) the zymogen, or trypsinogen-forming, granules, and (2) the 

 plasma containing the splenic ferment and the oxidizing substance 

 meet in this common lumen, which connects with the terminal 

 ramifications of the pancreatic duct. 



This is about as far as we can proceed at present, since we 

 can only surmise that, as soon as the products referred to meet 

 in the glandular lumen, the splenic ferment at once converts 

 the trypsinogen granules into liquid trypsin. Interesting in 

 this connection, however, is the fact, observed by Laguesse, 

 that 'long before the pancreas begins its function as a digestive 

 gland granules accumulate in the internal zones of the cells; 

 and when these come into contact with the blood a portion of 

 them appears as though dissolved/' As is well known, this is 

 precisely what happens even in true acini that do not belong to 



