and Laboratory Methods. '2485 



staining of tubercle bacilli by the Ziel-Neilsen method and that sputum after dis- 

 infection may be thus microscopically tested. H. w. c. 



Rosenau. An investigation of a Pathogenic The use of of a pathogenic bacterium, 

 Microbe applied to the destruction of Rats. ^ Typhi murium, for the destruction 

 Bui. V. U. b. Marine Hospital Service, 1901. ^^ 



of rats was advanced by Loeffler some 

 years ago and has been used with more or less success. Rosenau has experi- 

 mented as to methods of culture and use and has determined the interesting 

 point that if this bacterium is cultivated in contact with air it gradually loses 

 its pathogenic properties. If, after such cultivation, it is distributed so that rats 

 feed upon it, the rats are not injured by it but are actually rendered immune, 

 thus becoming protected from subsequent virulent cultures. Rosenau insists, 

 therefore, that the cultures used must be of the highest virulence or their distri- 

 bution will not only be useless but will actually render the animals more resist- 

 ent against any further attempts at their destruction. He regards the use of the 

 bacillus as preferable to the use of poisons for destroying rats inasmuch as this 

 organism is harmless to man. h. w. c. 



Lehmana. Beobachtungen liber die Eigenbe- No efforts have hitherto been made to 

 wegung der Bakterien. Arch. f. Hyg xlvi, determine the actual rapidity with 

 p. 311, 1903. ^ •' 



which motile bacteria can move, 



although the difference in velocity of different species is a matter of common 

 observation. Lehmann measures the velocity of movement by the simple means 

 of direct observation. The vigorous culture of the organism is placed in a 

 hanging drop and brought under the microscope. In the eyepiece is placed a 

 micrometer eyepiece, so adjusted that each division of the scale corresponds to 

 a known distance upon the slide. He then selects single bacteria which is in 

 rapid motion and determines the number of seconds required for it to pass the 

 distance from one division in the micrometer to the next. A large number of 

 such observations were made upon different individuals of the same culture and 

 then an average of the whole taken as the mean rapidity of motion. He found 

 that the cholera bacillus moves most rapidly of the species studied, moving at 

 the average rate of about one mm. in 34 ;f/^ seconds. B. megatherium moved the 

 slowest, moving about one mm. in 2 minutes and 11 seconds. h. \v. c. 



, . _, T^ ^ , . , , . ,, Lindner believes that the use of a 



Lindner. Der Tuschpinsel und seine Verwen- 



dung bei Aniage von platten kulturen, brush is a great convenience in study- 

 zur, " Pinselstrichkultur." Woch. f. Brau- ■ ^^^ relative number of bacteria in 

 erei, xx, p. 57 • 



contaminated water and similar fluids 



and especially in determining whether they are increasing or decreasing. He 

 sterilizes the brush, either in heat or by soaking in 94 per cent, alcohol, and dips 

 it in the liquid to be tested. Then he brings it into a tube of sterile water and, 

 after thorough washing and agitation, he draws the brush, taken from the diluted 

 mixture, over the surface of the Petri dish containing hardened culture medium. 

 The brush is then brought into a second tube of sterilized water and the bac- 

 teria remaining on the brush thus diluted a second time in water. In the same 

 way a second streak of inoculation is made, and a third dilution in the same 



