120 



C. C. WARDEN, J. T. CONNELL AND L. E. HOLLY 



Table 9 shows the results of the precipitation test with the 

 same serums. 



TABLE 9 

 Antigen No. 1. True Megatherium toxin broth. 

 Antigen No. 2. Artificial toxin broth, composed of 40 cc. broth containing 5 



mgm. of Typhoid protein and 2.4 mgm. of the K salts of the Megatherium 



antigen. 

 Each tube contained 0.5 cc. of antigen and 0.04 cc. of diluted serum. Readings 



taken as in table 7. 



These experiments showed that in all probability the arti- 

 ficial antigen was approximately correct. We observed in these 

 and in later tests that many normal rabbits have natural anti- 

 bodies against the B. megatherium and its toxin. This fact was 

 noted by Todd.^^ 



In order to test further the antigenic action of the artificial 

 fat complex, rabbits were immunized by divided S.Q. injections 

 of 0.5 mgm. doses emulsified both in broth and in salt solution. 

 Eight days after the sixth and last injection the rabbits were 

 bled and the serums separated and inactivated at 56°C. for 

 thirty minutes. The following table shows the results of com- 

 plement fixation carried out in the manner previously described. 



From these experiments it appeared that the serums of rabbits 

 immunized with th,e artificial antigen of B. megatherium con- 

 tained agglutinating and complement fixing antibodies in fair 

 amount together with strong antilysins. Connell had pre- 



13 Lancet, 1901, 2, 1663; Trans. Path. Soc. Lond., 1902, 53, 196. 



