PHYSIOLOGY OF THE LIVER AXD SPLEEN. 761 



theory cannot be considered at present as satisfactorily demon- 

 strated. (3) It has been suggested that the spleen is concerned in 

 the production of uric acid. This substance is found in the spleen, 

 as stated above, and it was shown by Horbaczewsky that the 

 spleen contains substances from which uric acid or xanthin may 

 readily be formed by the action of the spleen-tissue itself. More 

 recent investigations * hate shown that the spleen, like the liver 

 and some other organs, contains special enzymes (adenase, guanase, 

 and xanthin oxydase), by whose action the split products of the 

 nucleins may be converted to uric acid, and it is probable, therefore, 

 that this latter substance is constantly formed in the spleen. (4) 

 Lastly, a theory has been supported by Schiff and Herzen, according 

 to which the spleen produces something (an enzyme) which, when 

 carried in the blood to the pancreas, acts upon the trypsinogen con- 

 tained in this gland, converting it into trypsin. This view has been 

 corroborated by a number of observers, but it is difficult at present 

 to decide whether such an action occurs normally during digestion. 

 As already stated, the general testimony at present indicates that 

 the pancreatic juice when secreted contains its trypsin in inactive 

 form. It is activated only after reaching the duodenum under the 

 influence of the enterokinass. 



* Consult Jones and Austrian. " Zeitschrift f. physiol. Chem." 1906, 

 xlviii., 110. 



