EXPERIMENT STATION BULLETINS. 275 



suspect serum was used in the order named instead of .01, .02, and .04 c. c. 

 The tests were read after incubating for half an hour subsequent to 

 the addition of hemolysin and blood cells. The hemolysin was pro- 

 duced by injecting 0.75, 1.5 and 3 c. c. of pure washed blood cells in- 

 travenously every other day then waiting seven days before bleeding. 

 No glycerin was added to the antigen. 



THE AGGLUTINATION TEST. 



The antigen was prepared by growing several strains of Bad. a'bortits 

 on plain agar for forty-eight hours, then washing off the slants with 

 physiological salt solution contniiiiiig jilienol (0.5 per cent.) The anti- 

 gen was diluted with physiological salt solution until the opacity of 

 the bacterial suspension corresponded with 1.5 of McFarland's nephel- 

 ometer. Two cubic centimeters of antigen were added to each of four 

 tubes and 0.4, 0.2, 0.1 and 0.05 c. c. of serum diluted one to ten were added 

 in the order named. The tubes were incubated for two hours at 3'7°C. 

 then left at room temperature for twenty-four hours and readings taken 

 at that time. 



DETERMINATION OF SPECIFICITY OF THE INTRADERMAL TEST. 



Series I. 

 Nine guinea pigs were given intraperitoneal injections of live cul- 

 tures of Bad. abortus. Complement fixation, agglutination and intra- 

 dermal tests were run eight, sixteen, twenty-four and thirty-two days 

 after injection. Every animal developed positive reactions to all tests. 



Series 2, 

 Nine guinea pigs were injected with a suspension of killed Bad. abor- 

 tus for the purpose of immunization. Each pig received approximately 

 two, four and eight billions of bacteria intraperitoneally at five-day in- 

 tervals. Tests were run eight, sixteen, twenty-four and thirty-two days 

 after the last injection. All pigs developed positive reaction to the com- 

 plement fixation and agglutination tests while none reacted to the in- 

 tradermal test. 



Series 3 and 4. * 



The work recorded under series 1 and 2 was repeated using B. typhosus 

 in place of Bad. abortus. While all of the eighteen pigs developed posi- 

 tive reactions to the agglutination test using typhoid bacilli as antigen, 

 none reacted to the intradermal abortin test. 



Series 5. 

 Nine pigs infected with Bad. tuberculosis were tested with the in- 

 tradermal abortin test eight, sixteen, twenty-four, and thirty-two days 

 after inoculation. None of these pigs reacted to the test. All pigs died 

 of tuberculosis. One of these pigs died twenty days, and two of them 

 about thirty days after inoculation. 



EFFECT OF ATTEMPTED IMMUNIZATION ON THE INTRADERMAL REACTION. 



In order to see if attempted immunization prior to or after infection 

 would have any effect on the intradermal test, fifty-four guinea pigs 

 were subjected to various treatments as shown in the following tables. 



