372 ABSTRACTS 



conducted by (1) incubating antigen, serum and complement for one 

 hour; (2) adding cells and two units of hemolysin; (3) re-incubating 

 for one hour. The authors conclude from their study as follows: 

 "(1) Non-specific complement fixation by normal rabbit and dog sera 

 is probably due primarily to thermolabil and thermostabil antilytic 

 (anticomplementary) substances in the sera. (2) While fresh and 

 active rabbit and dog sera may yield non-specific complement fixation 

 the tendency is greatly increased as a result of heating the sera. At 

 56°C. the changes may occur in 20 minutes or even less; at 62''C. for 

 30 minutes the tendency for non-specific reaction is much decreased 

 and is entirely removed by heating serum at 70°C. for 30 minutes. 

 Changes may occur after exposure at 45°C. for 30 minutes, but the 

 optimal temperature is between 55° and 60°C. (3) In complement 

 fixation tests for specific antibodies with inactivated rabbit, dog and 

 mule sera, it is advisable to heat the sera at 62'^C. for one-half hour 

 and to use at least two units of complement or hemolysin and no more 

 than one-quarter of the anticomplementary unit of antigen after it 

 has been carefully titrated. (4) Complementoids and amboceptoids 

 probably bear no relation to the process of non-specific complement 

 fixation by rabbit and dog sera. (5) The blood corpuscles of various 

 animals and various bacteria may absorb a portion of the antilytic 

 substances from rabbit and dog sera, but they have much less influence 

 on the complement fixation reactions. Digestion of fresh sera with 

 corpuscles and bacteria not infrequently increases the anticomplemen- 

 tary properties of the sera. (6) Bacteriolytic amboceptors are not 

 responsible for non-specific complement fixation by normal rabbit 

 and dog sera. (7) Parasitic infestations of rabbits and dogs bear no 

 relation to the antilytic and complement fixing properties of the sera. 

 (8) Single, large doses of salvarsan are without definite influence on 

 the reactions with rabbit serum. (9) Quantitative factors in the 

 hemolytic system and antigen are of considerable importance in rela- 

 tion to these non-specific reactions. (10) If time permits, preliminary 

 complement fixation tests should be performed with the sera of rabbits 

 or dogs before immunization or inoculation is begun, and only those 

 animals selected the sera of which react negatively with the antigen 

 used."— P. B. H. 



INDUSTRIAL BACTERIOLOGY 



The Importance of Bacterium bulgaricus Groups in Ensilage. O. W. 

 Hunter and L. D. Bushnell. (Science, 43, 318-320.) 

 Various kinds of ensilage were examined at different stages of fer- 

 mentation. On acidulated glucose agar only Bacterium bulgaricus 

 and yeasts developed. The colonies of B. bulgaricus resembled Bacterium 

 lactis and the authors believe that it is on this account that other in- 

 vestigators have overlooked them. It is concluded that the Bulgarian 

 groups occur in sufficiently large numbers, and at a proper stage in 

 ensilage fermentation, to play an important role.— C. M. H. 



