THE PREPARATION OF CULTURE MEDIA 15 



successfully upon this iron - gelatine, amongst whicli 

 lie mentions the malignant oedema and the typhoid 

 bacillus in particular as producing such quantities of 

 sulphuretted hydrogen in this medium that, not only 

 did the gelatine in the immediate vicinity of the growth 

 become black, but the whole of the culture material as 

 well (see also p. 410 in tabulated description of typhoid 

 bacillus). 



In order to cultivate organisms in this material at 

 a higher temperature it is necessary to use agar-agar. 

 In addition to the iron solution a small quantity of 

 a 5 per cent, solution of sodium sulphate and some 

 glycerin should be added. 



Promme states that he was unable to discover any 

 organisms in the Marburg water which produced sul- 

 phuretted hydrogen in any marked quantity, although 

 this was not regarded by any means as an unimpeach- 

 able supply, and must have contained along with the 

 ordinary water bacteria many organisms derived from 

 polluting sources. 



Another method of qualitatively testing for the pro- 

 duction of sulphuretted hydrogen by bacteria in liquid 

 media is the well-known one and that employed and 

 recommended by Stagnitta-Balistreri.^ Pieces of lead- 

 paper are suspended in the inoculated flasks or test-tubes 

 •containing broth with or without peptone, and the 

 -change in the colour produced noted from deep black to 

 pale brown. During the investigations the lead-paper 

 must be daily observed, as, although the reaction may 

 be distinct at one time, it may subsequently disappear. 



An interesting table is given of the amount of 



^ ' Die Verbreitung der Schwefelwasserstoffbildung unter den Bak- 

 terien,' Archw fur Hygiene, 1892. See also * Beitrage zur Biologie der 

 krarLkheitserregenden Bakterien, insbesondere liber die Bildung von 

 Schwefelwasserstoff,' Petri and Maaszen, Arheiten a. d. haiserlichen Ge- 

 ^undheitsamte, vol. viii. 1892, p. 318. 



