THE SPLEEN AS AN EKDOCRIN OHGAN 669 



decreasing, although persisting to a slight degree for several months. 

 Griffin notes that leukocytosis is one of the most constant results following 

 splenectomy for pathologic conditions. 



The Spleen and the Blood-Producing Organs. Since removal of the 

 spleen produces definite changes in the blood, it was believed that certain 

 changes might also be found in the blood-producing organs, and such has 

 been noted to be the case. In the most recent article dealing with the 

 subject, by Pearce and Pepper, an extensive review of the literature 

 appears. 



Johnstone, who has studied the blood for kala-azar following sple- 

 nectomy in man, is now studying the problem in my laboratory. 

 Controlling one dog against another, he found it impossible to obtain con- 

 sistent results, A technic was devised, therefore, of removing and study- 

 ing bone-marrow of a rib at various intervals following removal of the 

 spleen. A few of the rather definite results are briefly as follows: 



Immediately after splenectomy leukogenesis is very active and reaches 

 its maximum activity quickly. In from one to three months it decreases 

 until it has resumed its preoperative degree of activity, or is even below 

 this. In about one-half of the animals there is a preliminary period in 

 which erythrogenesis seems dormant. It then becomes more and more 

 active until it exceeds the preoperative degree of activity. In the other 

 half of the animals erythrogenesis begins almost immediately after sple- 

 nectomy, but so slowly that it is difficult to detect. In either instance, it 

 usually reaches its maximum in from three to four months, remains sta- 

 tionary for two months longer, and then gradually decreases. It is inter- 

 esting that the marrow findings correspond to the blood picture after 

 splenectomy. 



It is difficult to postulate the relationship of the spleen to the blood 

 and the hematopoietic system. That there is some relationship is beyond 

 doubt. The evidence is not complete, however, to show that such a rela- 

 tionship is maintained by the intermediation of an internal secretion of 

 the spleen. 



The Spleen in Its Relation to Infection, Immunity, and 



Anaphylaxis 



The spleen has been considered related to infection, immunity, and 

 anaphylaxis. Here again the data from the various experiments do not 

 harmonize. While the spleen undoubtedly acts in a measure as a bacterial 

 filter, experiments have shown that the kidney serves this purpose quite as 

 well or better (Ozaki (a) (&)). It is still debatable whether the spleen 

 plays an important role in immunity, whether bacteria (Lewis and Margot 

 (a) (&) (c), Murphy and Ellis), tumor (Murphy, Morris, Woglom, Ste- 



