178 ADDENDUM 



employed but that such induced variations were largely tem- 

 porary. 



3. Other tests. Other tests which have been employed 

 to differentiate streptococci include morphological characters, 

 particularly the length of the chains, characters of the growth in 

 litmus milk and the characteristic methods of growth upon solid 

 media. 



All recent work is in the direction of showing that little 

 value can be attached to these tests. It should however be 

 mentioned that Crowe has recently demonstrated that charac- 

 teristic colonies of value for classification purposes are obtained 

 by the use of a neutral red egg medium. 



Agglutination reactions have been employed by some 

 workers but so far have not yielded results of special value. 

 Kligler has recently re-investigated this property for strepto- 

 cocci using sera obtained from four types as differentiated by 

 their haemolytic and fermentation characters. He found con- 

 siderable correlation between agglutination and the fermentation 

 characters employed since in general the serum of one fermenta- 

 tive type was capable of agglutinating only strains of that 

 particular group and not the others. The correlation of 

 agglutination with haemolysis was less in evidence. 



References. 



J. BROADHURST, Journ. of Infect. Diseases, 1912, x, p. 272 



J. BROADHURST, Journ. of Infect. Diseases, 1915, xvn, p. 277. 



H. W. CROWE, Proc. Royal Soc. of Medicine, 1913, VI, p. 119. 



D. J. DAVIS, Journ. of Infect. Diseases, 1914, XV, p. 378. 



C. A. FULLER and V. A. ARMSTRONG, Journ. of Infect. Diseases, 1913, xm, 



p. 442. 



J. G. HOPKTNS and A. LANG, Journ. of Infect. Diseases, 1914, xv, p. 63. 

 A. C. HOUSTON, Metropolitan Water Board : Tenth Research Report, June, 



1914, p. 22. 



F. JUPILLE, Ann. de Flnstitut Pasteur, 1911, xxv, p. 918. 

 I. J. KLIGLER, Journ. of Infect. Diseases, 1915, xvi, p. 327. 

 H. W. LYALL, Journ. of Med. Research, 1914, xxx, p. 487. 



