208 STUDIES IX IMMUNITY. 



analogous action of hemolytic sera is detectable in vitro as well as 

 intraperitoneally by a destruction of the corpuscles with a diffusion 

 of hemoglobin. 



To summarize: First, the sera under consideration obtained from 

 immunized animals are cytolytic, the cytolysis consisting in such 

 changes as the granular transformation of vibrios, and the hemolysis 

 of red blood cells. Certain fluids from the immunized animals, as 

 the peritoneal fluid, show similar cytolytic effects in vivo or in vitro. 

 And second, a given immune serum on injection into normal animals 

 confers on their serum and body fluids similar cytolytic properties 

 likewise demonstrable in vivo and in vitro. Immune serum trans- 

 mits this property even when itself deprived of its destructive prop- 

 erty by heating to 55 to 56 degrees. 



These are the facts to be coordinated and explained by a theory. 

 The first theory proposed was our own, offered first in 1895, and 

 confirmed without any essential addition by our subsequent re- 

 searches. It might seem unnecessary to rehearse our theory, as we 

 have already outlined and repeated it several times.* This theory, 

 however, has not been universally accepted and certain other 

 observers have preferred a different, one: it would therefore seem 

 advisable to reconsider it and to compare it with other theories. 



Borders theory (1895). — Our conception as expressed five years 

 ago is based on the possibility (first demonstrated by Metchnikoff) 

 of producing a granular transformation of vibrios in vitro, and de- 

 pends particularly on the following facts: 



1. Fresh cholera serum produces a granular transformation of 

 cholera vibrios; the phenomenon produced in vitro is identical with 

 the one first observed in the peritoneal cavity by Pfeiffer; it is just 

 as highly specific and may be similarly employed for the diagnosis 

 of vibrios. Cholera serum has also the power of clumping a culture 

 of vibrios. f 



2. When heated to 55 degrees cholera serum loses its bacterici- 

 dal property and the power of producing granular transformation, 

 but still retains its agglutinating power. 



* See articles on pp. 8, 56, 81, and 134. 



t This is the first instance described of the rapid agglutination of a micro- 

 organism by a specific serum in high dilution. 



