PATHOLOGICAL METABOLISM OF THE BLOOD 563 



indirect way be regulated by the spleen under normal conditions even 

 beyond fetal life is not at all improbable. 



It is known, for instance, that splenectomy in animals may often be 

 followed by an anemia, which reaches its height in from three to six 

 weeks, after which the blood gradually returns to the normal (Musser, Jr., 

 and Krumbhaar). It has not been determined, however, with any cer- 

 tainty whether the anemia which follows the removal of the normal spleen 

 is due to increased blood destruction or to diminished blood formation. 

 Some rough index as to the preponderance of one or the other of these 

 two processes has been sought for in determinations of the bile-pigment 

 excretion in splenectomized animals. While it is maintained by Mar- 

 tinotti and Barbacci and by Pugliese that after splenectomy the output 

 of bile-pigments drops to one-half normal, suggesting that excision of the 



Fig. 1. Composite curve of the red blood-cell court of seven dogs after splenec- 

 tomy. (After Pearce, Krumbhaar and Frazier, "The Spleen and Anemia," J. B. Lippin- 

 cott Company, 1918.) 



spleen in normal animals diminishes blood destruction, this observation has 

 not been confirmed by the careful experiments of Hooper and Whipple(e?). 

 These workers found that a bile fistula dog will put out the same average 

 amount of bile-pigments whether with or without a spleen. According 

 to this it would appear more likely that the anemia results from a dimin- 

 ished activity of the blood-forming organs, notably the bone-marrow. 



The evidence for this assumption, although not absolutely conclusive, 

 is very suggestive. For instance, it has been found both by Pearce and his 

 co-workers (Krumbhaar and Musser, Jr.) and recently confirmed by 

 Hooper and Whipple(cZ) that the repair of an anemia produced by hemo- 

 lytic poisons or by bleeding usually runs a longer course and is accom- 

 panied by less rapid regeneration of the blood in a splenectomized than 

 in a normal dog. It may be, therefore, that the absence of the spleen is 

 responsible in some way for the slow blood regeneration. 



A possible explanation of this retardation of repair in splenectomized 

 animals, and additional evidence in support of the view that the normal 

 spleen may exert a stimulating effect on the bone-marrow has come from a 



