838 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 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 sug- 

 gested 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. Later investigations 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, therefore, 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. 



