294 



SELLARDS. 



the 4 races of amcebfe, all of which were growing in conjunction with B. 

 prodigiosus. Complete tests for the comparison of the 4 races of amoebae 

 were carried out simultaneously, using sera of a low grade but sufficiently 

 active to give well-defined results. 



The data for these tests are shown in Tables V and VI. 



Table V. — Biological relationship of the various cultures of amoBbw. 



[First determination.] 



Serum. 



Lysis of amoebae. 



Immune to— 



Dilution. 



Race A. 



Race B. 



Race C. 



Race D. 



Race: 

 A-. 



I 1-5 

 I 1-10 



f ^~^ 

 1-5 



I 1-10 



1 - 



1 HO 

 1-2 

 1-5 



I 1-10 



1 " 



1 1-10 



Active. 



Active. 



Active. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



Active. 



Active. 



Slight. 



None. 



None. 



None.' 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



Active. 



Active. 



Active. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



Slight. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



Active. 



None. 



None. 



None. 



None. 



None. 



None. 



B 



C 



D 



Normal rablsit serum 



Control with water . 







Table VI. — Biological relationship of the various cultures of amcehce. 



[Second determination.] 



Serum. 



Lysis of amoebae. 



Immune to— 



Dilution. 



Race A. 



Race B. 



Race C. 



Race D. 



Race: 



A 



{ 



1-2 

 1-5 

 1-2 

 1-5 

 1-2 

 1-5 

 1-2 

 1-5 

 1-2 

 1-5 



Active. 



Active. 



None. 



None. 



None. 



None. 



None. 



None. 



I None. 



None. 



None. 



None. 



Active. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None 



None. 



Active. 



Active. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



Active. 



Slight. 



None. 



None. 



B 



-...— 



D - 



Normal rabbit serum 



Control with water» 







It is clear from these tables that the 4 races of amoebae are, biologically 

 at least, distinct species, since the sera produced by them show a definite 

 specificity. ^ Here again it seems a little unusual that the first four races 



