632 



STATE BOARD OF AGRICULTURE. 



fixation tests might be of value in locating Bad. abortus infected udders 

 and in studying the presence of this organism in milk. Tests were made 

 using milk and milk serum instead of the usual method of using blood 

 serum. Bad. abortus was used as antigen. 



TECHNIC EMPLOYED. 



Complement-Fixation Test. — A modification of the complement-fixa- 

 tion test as used by Surface was employed in the work. These modifi- 

 cations were made by I. F. Huddleson. Antigen was prepared for the 

 test by growing a culture of Bad. abortus upon ordinary agar, for 48 

 hours. The growth was then washed ofl: with a solution containing 0.9 

 percent sodium chloride and 0.5 per cent phenol. The suspension was 

 filtered through a coarse filter paper and standardized so that the turbid- 

 ity compared with tube 5 of McFarland's nephelometer. The suspension 

 was then shaken for five hours to obtain homogeneity. When placed in 

 a dark bottle and stored at 5° C. the titer of this antigen was found to 

 remain constant for many months. No modifications were made in the 

 preparation of complement, hemolysin and positive serum or in their 

 titration. The outline shoAvn in the table below was followed for these 

 tests. 



OUTLINE^FOLLOWED FOR COMPLEMENT FIXATION TEST. 



(a) Add sheep cells during first incubation to determine presence of natural hemolysin. 



(b) Two times titer found on titration. 



Kennet milk serum was used in the following quantities: 0.1, 0.04, 

 0.02, and 0.005 c.c. 



Agglutination Test. — Antigen was prepared for the agglutination test 

 in the same way that it was prepared for the complement-fixation test 

 except that it was not shaken and was standardized so that the turbid- 

 ity compared with tube 1.5 of McFarland's nephelometer. Four c.c. of 

 this bacterial suspension was placed in each of the small test tubes and 

 the following quantities of milk added : 0.1, 0.05, 0.025, 0.01, and 0.005 

 c.c. In this way approximate dilutions of 1 to 50, 1 to 100, 1 to 200, 

 1 to 500, and 1 to 1,000 were obtained. It was found that turbidity due 

 to the whole milk added did not interfere with the reading of the re- 

 action. When a dilution lower than 1 to 50 was made, rennet milk 

 serum was used. 



INVESTIGATIONAL WORK. 



It has been proposed by some investigators of infectious abortion 

 that milk be used as a means of diagnosis. As it is often much easier 



