THE SPLENO-PANCREATIC INTERNAL SECRETION. 399 



"In the human pancreas lobules and lobule groups are not 

 so regularly arranged as in the cat. But both structures are 

 more or less clearly definable. The lobules vary much in 

 size, and are usually not clearly separated from one another. 

 Though an island of Langerhans is often situated in the cen- 

 ter of a more or less clearly defined lobule, no constancy of 

 position is discoverable. The lobule groups are separated by 

 relatively wide bands of loose areolar tissue in which are con- 

 tained the medium-sized ducts, the blood-vessels, and the 

 nerves. Within a lobule group the arteries and veins, which 

 are side by side, do not, as in the cat, accompany the ducts." 



The multiplicity of facts reviewed in the foregoing pages 

 and the intricacy of the whole question make it necessary to 

 collate and group in logical sequence the salient features of 

 .each subject discussed, in order to render a fruitful compari- 

 son of their merits possible. Not only are we required to 

 analyze the questions involved in the light of the solid data 

 that the last forty years have furnished, i.e., since Schiff 

 first studied the relations between the spleen and the pancreas, 

 but all these must likewise be sustained by, and be in accord 

 with, the functional mechanisms of the organs involved as we 

 interpret them, if our own views are well founded. If they are, 

 they must necessarily assist us greatly in elucidating the 

 various problems, physiological and pathological, to which ref- 

 erence has been made, since the very elements which they in- 

 troduce bear upon a predominating factor in all these proc- 

 esses: i.e., oxidation. To this subdivision of the subject we 

 will, therefore, turn our attention. 



Can we ascribe to oxygen, or rather to the oxidizing sub- 

 stance of the blood, the conversion of pancreatic trypsinogen 

 into trypsin? We have seen that in both the spleen and pan- 

 creas the oxidizing substance seems, as elsewhere, to play the 

 main functional role; the extrinsic and intrinsic vessels are 

 disposed in a similar manner as regards their nervous rela- 

 tions, and vasoconstriction calculated to increase the flow of 

 blood through both organs is similar. Moreover, we have seen 

 that in the spleen the dilation incident upon malarial in- 

 toxication could be traced to the adrenals, the primary source 

 of excessive oxidation, while in toxic glycosuria we obtained 



