290 



SELLARDS. 



Table I. — Production of cytolysins hy injection of amcebw in mixed culture with 



B. prodigiosus. 



Serum of rabbit 

 immune to— 



Agglutination of B. prodigiosus— 



Lysis of amoebae in cultivation 

 with— 



In pure culture 

 at dilution of— 



In mixed 

 culture with 



amoebffi at 

 dilution of— 



B. prodigiosus 

 at dilution of— 



V. cJwlerse at 

 dilution of— 



Experi- 

 ment 

 I. 



Experi- 

 ment 

 II. 



Experi- 

 ment 

 I. 



Experi- 

 ment 

 II. 



Experi- 

 ment 

 I. 



Experi- 

 ment 

 II. 



Experi- 

 ment 

 I. 



Experi- 

 ment 

 II. 



B, prodiffiosus 



1-50 



1-5 

 (Slight. 

 I 1-2 



1-100 



1-5 



None. 



1-2 



1-50 



1-10 



None. 



1-2 



1-50 



1-5 



None. 



1-2 



(None. 

 I 1-2 



1-5 



None. 



1-2 



None. 



1-2 



1-10 



None. 



1-2 



None. 

 1-2 

 1-5 



None. 

 1-2 



None. 

 1-2 

 1-5 



None. 

 1-2 



Amoebae and B. prodigiosus - 

 Control, normal rabbit 

 serum 





From these data it appears that the lysis of the amoebae was due to 

 the immune bodies formed in response to the injection of the amoeba, 

 and not to the accompanying bacteria, since the amoebse growing with 

 cholera were acted upon by the serum produced by the injection of 

 amoebse and B. prodigiosus, whereas the serum produced by the injection 

 of B. prodigiosus alone was inactive for amoebas. In the comparison of 

 the different races of amoebse it will be seen that there is some additional 

 evidence in support of the preceding conclusions. 



The activity of the serum is of extremely low grade even for protozoan 

 material. The highest serum which was obtained at any time was that 

 from a rabbit which had survived on the first injection 1 agar slant of 

 amoebae. The same dose was fatal for 5 other rabbits. Five months 

 after the first injection, when the rabbit was able to withstand 4 agar 

 plants intraperitoneally at one injection, the serum was found to be 

 active in 1 to 50 dilution. This degree of activity persisted for only 

 2 days and then fell to 1 to 10 ; subsequent injections failed to increase 

 it. Apparently, the repeated injections of amoebaa instead of producing 

 highly active sera only caused the low grade of activity to persist over 

 longer periods. In considering the degree of activity which was obtained, 

 it is to be noted that the amounts of material injected were rather lower 

 than are ordinarily used in working with animal cells, such as red blood 

 corpuscles. The quantities used were probably not as great as are usually 

 employed for many of the ordinary bacteria such as V. cholerce or B. 

 typhosus. Two factors were concerned in producing this limitation, 

 namely the relatively small quantity of amoebse Avhich can be obtained 

 from the growth on agar and the inability of animals to withstand the 

 injections, emaciation and death resulting from an over dosage. 



