434 B A OTERIO LOGY. 



jectecT to the usual tests for the recognition of the 

 bacillus typhosus, and have always corresponded in 

 all their reactions to those given by the typical typhoid 

 bacillus. 



ELSNER'S METHOD. 1 As Eisner himself gives no 

 very definite details as to the steps to be taken in 

 making up his medium, those working with it have 

 developed their own modifications. We found the 

 following method to give satisfactory results : 



1. Grate 0.5 kilogramme of small potatoes to a fine 

 pulp, add 1 litre of water, and allow the mixture to 

 stand in a cool place over night. 



2. Mash thoroughly (meat-press is best) and strain 

 through a fine cloth. This must be done when the 

 mixture is cold or the swelling of the starch-granules 

 will prevent the filtering process. 



3. Boil the filtrate and filter again. 



4. Add 10 per cent, of gelatine and dissolve by 

 boiling. 



5. Test for the acidity. Eisner used litmus as an 

 indicator, and advised that the medium be of such an 

 acidity as to require the addition of 2.5 c.c. of deci- 

 normal hydroxide solution to make it neutral. If 

 more than 2.5 c.c. are required the acidity must be 

 reduced by normal sodic hydrate solution. Abbot 

 advises using phenolphtalein as the indicator, and 

 making the reaction such that 3 c.c. of the decinormal 

 solution will neutralize 10 c.c. of the medium. 



6. Boil and clarify with an egg. 



7. Filter first through cotton and then through 

 paper. 



i Zeitschrift fur Hyg. und Infek., 1896, Bd. xxi. S. 25. 



