K. E Meyer 445 



polyblasts in the medullary sinuses appear to be attributable to the action 

 of the Brucella organism. Through culture and through bacterioscopic ex- 

 amination the heavy invasion of the nodes was definitely proved. Just as in 

 typhoid fever, so in brucellosis a definite relationshi}) exists between these 

 cellular elements and the bacteria. Perhaps the phagocytic activity of these 

 cells is important in the immunity mechanisms. Von Albertini and Lieber- 

 herr* have noted the frequent involvement of the portal and retroperitoneal 

 lymph nodes in Bang's disease, and although the duration of the disease was 

 approximately five months in one of their cases the lesions were quite similar 

 to those seen in the organs of D.S. Definite epithelioid nodules, which replace 

 the lymphoid structures, are missing, but the aggregates of monocytes inter- 

 spersed by lymphocytes and a few polyblasts are unquestionably precursors 

 of the focal or diffuse structures found in the lymph nodes, liver, spleen, bone 

 marrow, etc., of human brucellosis. These nodular reactions, with which every 

 pathologist is familiar, since they were described by Smith and Fabyan,^ by 

 Fabyan,-^ and by Smith"^ were first recorded by Loffler and v. Albertini"* and 

 shortly thereafter by WohlwilF in a human autopsy specimen from proved 

 Bang infections. Subsequently, their presence has been amply confirmed by 

 many investigators (see Rabson^). However, not every fatal Bang infection 

 exhibits this nodular reaction. In fact, as autopsy reports and microscopic 

 tissue examinations accumulate, it becomes apparent that these focal in- 

 flammatory or proliferative processes, although characteristic, and in their 

 later stages diagnostically significant for Brucella infections, are the excep- 

 tion rather than the rule. That they are the resultants of reactions which 

 take place in the reticulo-endothelial system in response to the phagocytosis 

 of bacilli in the blood or lymph streams, there is little doubt, but the im- 

 munobiological factors responsible for their formation are entirely unknown. 

 Rossle"' "* interprets these cellular aggregates as an expression of allergic re- 

 actions. Until the mechanism of the immunity in Brucella infection is really 

 understood, it is advisable to abstain from premature attempts to explain 

 these nodular lesions. While their genesis remains a fascinating study subject 

 to experimental analysis, it is apparent that these structures contribute an 

 important share to the well-known latency and chronicity of undulant fever. 

 In this connection, it should be recalled that dead brucellas or their protein 

 may produce similar lesions in the sensitized hosts; consequently one may 

 encounter nodules which are bacteriologically sterile. 



It is reported with increasing frequency that the hepato-licnal syndrome 

 governs a Bang infection. Aside from the pathology in the liver, the most 

 obvious and general gross changes, particularly in cases of long standing, is 

 the enlargement of the spleen. On account of the rapid course of the infec- 

 tion in the patient, D.S., the splenic organ showed merely the early stages of an 

 inflammatory reaction, accompanied by hemorrhagic engorgement which sub- 

 merged the follicles. The diffuse reticulo-endothelial hyperplasia might pos- 

 sibly be interpreted as early stages of the "tuberculoid reaction" so frequently 



