AGGLUTINATION AND DISSOLUTION. 183 



in the serum of certain animals than they are in the serum of other 

 animal species. 



Since heat weakens the agglutinating property of sera for cor- 

 puscles or bacteria, the question arises as to whether the property 

 of sensitizing cells to the action of alexin present in specific sera 

 is diminished in a similar way. The question is not without in- 

 terest, as it may throw some light on the problem of whether the 

 phenomenon of sensitization is due to the same or different sub- 

 stances than the phenomenon of agglutination. We shall not under- 

 take to consider this subject here, but reserve for a future time 

 a discussion of the significance of facts bearing on this question.* 



We shall content ourselves with noting that the exposure of specific 

 sera to temperatures ranging from 65 to 75 degrees, which distinctly 

 enfeebles their agglutinating and immobilizing power, also distinctly 

 diminishes their sensitizing power. When cholera serum from the 

 rabbit has been heated to 70 degrees it is less energetically agglu- 

 tinating for the vibrio and is also slightly less sensitizing. Such a 

 diminution in strength may be demonstrated by placing vibrios in 

 contact with small doses of the serum heated to 55 degrees and to 

 70 degrees respectively. These emulsions are not equally well agglu- 

 tinated. On adding normal serum to each emulsion it is found 

 that the granular transformation is much less extensive in the 

 emulsion containing serum heated to 70 degrees than in the one 

 with serum heated to 55 degrees. A similar difference in trans- 

 formation may be noted in vivo on intraperitoneal injection of the 

 emulsion. Guinea-pigs receiving the emulsion with serum heated 

 to 55 degrees have an exudate showing a granular transformation 

 of the vibrios, and the animals recover; in the other animals motile 

 vibrios remain and a fatal infection ensues. If more than minimal 

 doses of serum are employed, the difference between the two emul- 

 sions naturally is not so distinct ; we may repeat that the weakening 

 effect of heat on the properties of the serum is only partial. A 



* Agglutination is a complex phenomenon. For example, when motile bacteria 

 are concerned agglutination includes and necessitates an immobilization of these 

 bacteria. It has not been demonstrated, so far, whether the two phenomena 

 of immobilization and agglutination are due to the same substance. It would 

 seem probable when we consider the experiments that we have already performed 

 and particularly those dealing with the effect of salt solution on agglutination that 

 agglutination depends on the cooperation of several different factors. 



