IMMUNITY REACTIONS WITH AMCEB^. 297 



and in the other with amcebs cultivated from a dysenteric stool. In 

 both instances, the tests were carried out at a time when the cultures were 

 gTOwing only moderately well. Both reactions were obtained in 1 to 2 

 dilution and it is not unlikely that the al)sence of amoebae is to be ac- 

 counted for by the excessive growth of bacteria. 



In as much as these tests failed to show any evidence of immunity, it 

 seemed desirable to carry o.ut some of the reactions with amoebae known 

 to be pathogenic, and to this end an attempt was made to utilize dysenteric 

 stools in which the amoebae were very numerous. The serum reaction as 

 used with cultures of amoebae, requires some modification in applying it 

 tda dysenteric stool, since the amoebas disintegrate within a few hours in 

 the stool itself, or in any ordinary culture medium. Accordingly, mix- 

 tures of stools containing numerous amoebae and the sera from dysenteric _ 

 patients were made in the same manner as for cultures of . amoebae to 

 determine whether any changes would take place within a few hours, be- 

 fore the control preparations deteriorated. 



Two patients were selected in which the stools consisted largely of 

 blood and mucus, practically free from fgecal matter and in which the 

 amoebae were numerous in every field. Equal parts of these stools were 

 mixed, first with the undiluted sera from the corresponding patients; 

 second, with the serum from a case with acute symptoms of dysentery; 

 and third, with serum from a patient who about three weeks previously 

 had recovered from an acute attack of dysentery. Control preparations 

 were made from normal serum. The amoebae remained alive and active 

 for a period of 2 hours. At the end of 3 hours the motility was much 

 diminished in all preparations and the amoebae were disintegrating in the 

 preparations with the sera of dysenteric cases and in the control prep- 

 arations as well. Further work upon the aetiology and diagnosis of 

 amoebic dysentery by immunity reactions did not appear to be feasible 

 on account of the lack of cultures known to be pathogenic. 



SUMMARY. 



The injection of cultures of amoebae into rabbits resulted in the pro- 

 duction of serum which was cytolytic for amoebae. 



This serum possessed only a low grade of activity. Ko inactivation 

 resulted after exposure to a temperature of 60° C. for periods varying 

 from thirty minutes to three hours or 70° C. for thirty minutes. How- 

 ever, the anti-bodies of the sei*um were not proved to be thermo-stable, 

 since normal serum became active when heated for one hour at G0° C. 



Of the sera produced by 4 cultures of amoebae obtained from parasitic 

 and from saprophytic sources each serum was cytolytic for the correspond- 

 ing culture, but not for the other three. This specificity indicates that 

 these amoebae are biologically distinct. Subsequent examination showed 



