182 APPLIED BACTERIOLOGY 



many normal sera will act, even when diluted, if left an 

 indefinite time. 



Eisner's Method of Diagnosis. — Dr. Eisner, of Berlin, has 

 recently published* the results of an investigation made 

 to ascertain the possibility of the early recognition of 

 enteric fever by the bacteriological examination of the 

 stools. 



The author went over the existing methods for the 

 separation of B. coli and typhosus from other organisms 

 and from each other, with no better results than have been 

 previously obtained. In all cases but one he found that 

 either persistent organisms other than those sought to be 

 isolated would grow to an extent sufficient to spoil the 

 plate, or else the B. coli would develop to an extent capable 

 of preventing the recognition of the typhoid bacillus. The 

 exception was potato gelatine, slightly acid, and mixed with 

 1 per cent, of iodide of potassium. With this medium the 

 author examined all the waters he could obtain, and he 

 found that even the B. proteus and ramosus, which on 

 carbolised gelatine would always grow, either never 

 occurred on his medium or were rapidly overgrown by the 

 B. coli. The B. coli grew in twenty-four hours, presenting 

 the usual appearance of that organism on acid media ; the 

 B. typhosus was scarcely visible in twenty-four hours, but 

 in forty-eight hours appeared in small, shining, very finely- 

 granulated colonies, like little drops of water, which con- 

 trasted strongly with the larger, much more coarsely 

 granulated, and brownish colonies of B. coli. The B. coli 

 only acquired the appearance of the typhoid colonies when 

 a very large quantity was used in an inoculation, and many, 

 therefore, grew without finding room for their proper 

 development. In secondary plates, or in plates made with 

 weaker inoculation, it was almost impossible to mistake 

 * Zeitschr. f. Hyg., xxi., 1. 



