ZOOLOGY AND BOTANY, l^IICROSCOPY, ETC. 627 



The authors selected certain members of two of these groups, and have 

 studied their action on caseinogen and amino-acids from the point of 

 view of colour -production. 



The two groups selected were the Bacillus proteus group and Gram- 

 negative bacilli, which produced an alkaline reaction in solutions of various 

 sugars, alcohols, etc. The results show* that the members of the former 

 group produced a well-marked amber colour in media containing trypto- 

 phane, whilst those of the latter group caused a yellow colour to appear 

 in media containing tryptophane, and a definite brown colour in casein- 

 ogen solutions. 



Invisible Microbe antagonistic to Dysenteric Bacilli.* — F. 



d'Herelle has isolated from the stools of persons convalescent from 

 bacillary dysentry an invisible microbe endowed with properties antago- 

 nistic to Shiga's bacillus. More evidence seems to be required on this 

 subject. 



* Comptes Rendus, cliv. (1917) pp. 373-3. 



