272 STATE BOARD OF AGRICULTURE. 



Experimental Work. 



THE ABORTIN. 



Two kinds of abortin were employed, namely: Tlie alcohol-ether 

 extract of Bad. abortus as prepared by Fleischner and Meyer (2) and 

 the bacillary suspension of the same organisms as prepared by Reichel 

 and Harkins (3). The latter is more easily prepared and was found 

 to give better results than the former. In place of attempting to esti- 

 mate the number of bacteria per cubic centimeter by counting the 

 organisms, tube No. 7 of McFarland's nephelometer was selected as 

 a standard for the opacity of the suspension. After finding that the 

 suspension of dead bacilli produced better results than the alcohol 

 ether extract the former was used exclusively. 



APPLICATION OP THE INTRADERMAL TEST TO GUINEA PIGS. 



An area of the abdomen of about three square cm. was clipped, 

 shaved and disinfected. Into the skin of this area O.lcc. of bacillary 

 suspension was injected with a 27.5 gauge needle. A swelling of the 

 size of a si>lit pea should appear, the color of which should be char- 

 acteristically whitish when working with light colored guinea pigs. 

 This swelling should not have a tendency to disappear immediately nor 

 to diffuse. If this occurs it is an indication that the material is being 

 injected subcutaneously and the injection should be repeated in a dif- 

 ferent place. Eeadings are taken forty-eight hours after injection. 



THE REACTION. 



The reaction consists of an area of induration varying in size from 

 0.5cm. to 1.5cm. in diameter and appearing about 24 hours after the 

 injection. In exceptional cases indurated areas of 2cm. in diameter 

 have been found. At first a decided redness over the swelling is noticed 

 in guinea pigs with light colored skin. As the induration increases 

 the redness disappears and is followed by a color similar to that of 

 cartilage. At the end of two or three days an area of necrosis ap- 

 pears in the center of the swelling. These areas of necrosis have been 

 found to vary from 0.2 cm. to 1.5 cm. in diameter. Employing the 

 alcohol-ether extract it was found that the reaction would appear 

 and disappear more quickly than when the bacillary suspension was 

 used. In cases where the former test fluid w^as used the reaction would 

 be at its height at the forty-eighth hour and would be almost unnotice- 

 able ai: the end of four to five days. When employing the latter prepara- 

 tion the reaction would as a rule gradually increase up to the fourth 

 day and then gradually diminish, seldom disappearing entirely before 

 the tenth day after the application of the test. 



THE COMPLEMENT FIXATION TEST. 



The method employed in the complement fixation test was that des- 

 cribed in Giltner's Manual of General Bacteriology (4) with the follow- 

 ing changes : A two per cent, suspension of blood cells was used in place 

 of ne per cent ; two times the known titre of complement was used in 

 the titration of antigen and the test proper; .04, .02, .01,, and .005 c. c. of 



