828 PHYSIOLOGY OF DIGESTION AND SECRETION. 



bases, such as xanthin, hypoxanthin, adenin, guanin, and uric acid. 

 The presence of these bodies seems to indicate that active metabolic 

 changes of some kind occur in the spleen. As to the theories of the 

 splenic functions, the following may be mentioned: (1) The spleen 

 has been supposed to give rise to new red corpuscles. This it un- 

 doubtedly does during fetal life and shortly after birth, and in some 

 animals throughout life, but there is no reliable evidence that the 

 function is retained in adult life in man or in most of the mammals. 

 The presence of a large amount of iron in organic combination 

 suggests, however, that the spleen may play a part in the prepara- 

 tion of new hemoglobin, or in the preservation of the iron set free 

 by the death of the red corpuscles. This suggestion is strengthened 

 by the fact that after extirpation of the spleen there is a distinct 

 increase in the daily loss of iron from the body, in dogs an increase 

 from 11 to 18 or 29 mgm.* (2) It has been supposed to be an 

 organ for the destruction of red corpuscles. This view is founded 

 chiefly on microscopical evidence, according to which certain 

 large ameboid (endothelial) cells in the spleen ingest and destroy 

 the old red corpuscles, and partly upon the fact that the spleen 

 tissue seems to be rich in an iron-containing compound. (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 con- 

 tains substances from which uric acid or xanthin may readily be 

 formed by the action of the spleen-tissue itself. Later investiga- 

 tions f have 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 xanthin or hypoxanthin, and it is possible, there- 

 fore, that these substances may be formed in the spleen. 



* Grossenbacher and Asher, "Zentralblatt f. Physiol.," No. 12, 1908. 

 t Consult Jones and Austrian, "Zeitschrift f. physiol. Chem.," 48, 110, 

 1906. 



