CHAP, iv.] METABOLIC PROCESSES OF THE BODY. 779 



476. The Chemical Constituents of the Spleen. Besides the 

 chemical bodies which one would expect to find in a vascular, 

 muscular organ full of blood, the spleen contains bodies, lodged 

 apparently in the spleen pulp, which give it special chemical 

 characters. One of the most important of these is a special proteid 

 of the nature of alkali-albumin, holding iron in some way peculiarly 

 associated with it. The occurrence of this ferruginous proteid, 

 accompanied as it is by several peculiar but at present little 

 understood pigments, rich in carbon, which are partly present in 

 the cells spoken of above and partly deposited in the branched 

 cells of the reticulum, appears to be connected with the changes 

 undergone by the haemoglobin which we shall presently discuss. 

 The inorganic salts of the spleen, or at least those of its ash, are 

 remarkable for the large amount of both soda and phosphates, and 

 the small amount of potash and chlorides which they contain, thus 

 differing from those of blood-corpuscles on the one hand, and from 

 those of blood-serum on the other. But perhaps the most striking 

 feature of the spleen-pulp is its richness in the so-called extractives. 

 Of these the most common and plentiful are succinic, formic, acetic, 

 butyric and lactic acids, inosit, leucin, xanthin, hypoxanthin and 

 uric acid. Tyrosin apparently is not present in the perfectly fresh 

 spleen, though leucin is : both are found when decomposition has 

 set in. The constant presence of uric acid is remarkable, especially 

 since it has been found even in the spleen of animals, such as the 

 herbivora, whose urine contains none. 



The richness of the spleen in these extractives is an indication 

 of the importance of the metabolic events with which the organ 

 has to do ; but it will be more profitable to discuss what goes on 

 in the spleen in connection with the metabolic changes in other 

 parts of the body, in the liver for instance, than to attempt to lay 

 down any so-called ' functions ' of the spleen. When we confine 

 our attention to the spleen itself we learn very little; thus the 

 whole organ may be successfully removed without any very obvious 

 changes in the economy resulting. We may return therefore to 

 the discussion of the formation of the bilirubin of bile, and of the 

 changes undergone by haemoglobin, with which as we shall see 

 the spleen is connected, and which moreover has to do with the 

 formation of other pigments. 



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UNIVERSI 



