Aug. i6. I920 Germ-Free Filtrates as Antigens 515 



seem necessary to resort to the anaerobic cultural examination of the 

 culture flasks. Calves inoculated with blackleg filtrate showing a satis- 

 factory antigenic value were rendered sufficiently immune, after a period 

 of three to four weeks, to withstand intramuscular injections of 100 to 

 200 mgm. of virulent blackleg muscle powder, a quantity sufficient to kill 

 unvaccinated calves in two to three days. 



Failure of a blackleg filtrate to possess an antigenic titre of from i/io 

 to 1/20 the anticomplementary dose should arouse the suspicion that the 

 blackleg organism did not grow under favorable conditions, that some 

 contamination is present, or that the organism being used was not the 



blackleg organism at all. 



CONCLUSION 



From the data at hand it can be said that — 



(i) A blackleg filtrate produced under favorable conditions will 

 possess a distinct antigenic value demonstrable by the complement- 

 fixation test. 



(2) Those blackleg filtrates that conferred a solid immunity on calves 

 were found to possess a high antigenic titre. 



(3) The complement-fixation reaction should be of much value as a 

 laboratory control test to determine whether the filtrate has been pro- 

 duced under conditions favorable to the blackleg organism or whether 

 the blackleg organism has been supplanted in part or wholly by con- 

 taminating anaerobic microorganisms. 



(4) Botulinus filtrate also acts as an antigen in the complement- 

 fixation test when type B serum is used with type B filtrate' but fails to 

 cause fixation when one type of serum is used with the other type of 

 filtrate as antigen. 



(5) The phenomenon of germ -free filtrates acting as antigens in the 

 complement-fixation test is new and promises to play an important part 

 in the differentiation of the spore-bearing anaerobes, more especially those 

 having closely similar cultural characteristics. 



183719°— 20 i 



