62 BACTERIOLOGY 



a Bunsen burner, and the gelatine rolled out by Esmarch's 

 method. 



In order to displace the air in a test-tube by means of 

 hydrogen, Fuchs recommends that the inoculated tube 

 should be inverted and hydrogen conducted into it from 

 below through a glass pipe, after which the test-tube is 

 closed with a rubber cork. 



For test-tube cultivation, however, Liborius' method of 

 preparing high cultures is specially adapted. A tube is filled 

 high up with gelatine or agar, which is then freed from air 

 and oxygen by thorough boiling and is cooled to 40 ; the 

 matter to be inoculated is distributed in it as evenly as pos- 

 sible with a platinum needle, and it is made to set rapidly in 

 iced water. By this means the deeper layers of the nutrient 

 mass are protected from the air by those higher up, while 

 the superficial ones are exposed to the action of oxygen. 

 When several varieties of bacteria develope, a means is 

 hereby afforded of distinguishing the aerobes which grow 

 on the surface, from the anaerobes growing in the deeper 

 parts. 



High cultures are also used for obtaining thrust culti- 

 vations (Stichculturen) of anaerobic micro-organisms, the 

 platinum needle charged with infecting matter being thrust 

 as deeply as possible into the stiff nutrient mass. Although 

 at first development only occurs in the deeper parts, the 

 growth gradually mounts upwards as the gaseous products 

 of its metabolism displace the air from the higher layers of 

 the medium. 



Nikiforoff cultivates the anaerobes in the ' hanging drop.' 

 A cover-glass is prepared with an inoculated drop of bouillon 

 and sealed to a hollowed slide with a layer of vaseline. 

 Between the edge of the cover-glass and that of the well in 

 the slide, the contents of a platinum loop of strong solu- 

 tion of pyrogallol are allowed to flow in on one side, and 



