VACCINE-THERAPY 



59 



Agglutinins. 



Gruber and Durham have shown, when the serum of an 

 animal suffering from a bacterial disease is added to a 

 culture of the specific bacterium of that disease, they col- 

 lect together in masses, leaving the rest of the fluid free 

 from their presence. It is supposed they (agglutinins) are 

 formed in lymphoid tissue, marrow, and the spleen, while 

 Metchnikoff noticed the peritoneal exudate was even richer 

 than the blood itself in agglutinins. 



Strangely enough, the agglutination of bacteria seems to 

 protect them from the death-producing action of another 

 antibody— i.e., lysin ; and if that is so, Nature would appear 

 to be working against her own interests and defeating her 



A B 



Fig. 29. — Agglutination of Bacteria (Jowett). 



A, Bacteria evenly distributed ; B, Bacteria agglutinated by serum. 



own ends — a very improbable presumption. Allen is of 

 opinion, however, the bacteria are gathered into clumps in 

 the manner just described, so that they may be caught up 

 in the various tissues, such as the liver, the spleen, and 

 lymphatics, where the immunizing bodies are generated, and 

 their destruction thereby brought about. 



Widal first suggested using this agglutinating power for 

 diagnostic purposes, and the test now bears his name. It 

 was found that many kinds of micro-organisms were clumped 

 by the serum of animals immunized against them. It was 



