100 A MANUAL OF BACTERIOLOGY 



but a little practice is required to get it evenly distributed. 

 The colonies then develop in the film of gelatin, which is 

 quite analogous to a film in a Petri dish. 



Anaerobic plate cultivations are sometimes required. 

 Bulloch's apparatus (p. 89) may be used, or a wide- 

 mouthed glass jar large enough to hold three or four 

 Petri dishes. The jar should have ground edges so that 

 a lid may be fitted air-tight with grease. Some alkaline 

 pyrogallol is introduced into the jar, and the dishes should 

 be raised above it by standing on a glass capsule. 



The Mclntosh and Fildes' method (p. 89) may be used 

 with a jar of suitable size. 



The Esmarch roll cultures can be adapted for anaerobic 

 cultures. After preparation, the wool plug is replaced by 

 a rubber cork with two holes, through which inlet and 

 outlet glass tubes pass, as in Frankel's anaerobic tubes 

 (Fig. 16), hydrogen is passed through for a quarter of an 

 hour, and the tubes are sealed off. 



Golding's flask (p. 98) or a " plate " bottle (Fig. 19) 

 may be similarly used, or a Golding flask may be inverted 

 over a beaker of alkaline pyrogallol. 



Various devices may be employed for single dishes, 

 if jars are not available. The dish may be inverted and 

 alkaline pyrogallol placed in the lid ; this absorbs the 

 oxygen and at the same time seals the preparation. Or 

 a little solid pyrogallol may be placed in the lid and 

 moistened with alkali and the bottom may be luted down 

 over it with plasticine. 



Single-cell cultures. With large organisms, such as 

 yeasts, it is not difficult to obtain growths from single 

 cells by making miniature plate cultures on ruled cover- 

 glasses and ascertaining where single cells are located in the 

 film by examining the preparation with a J or J in. objec- 

 tive (see Chapter XVI). But with the minute bacteria 

 this method is inapplicable. Burri's Indian ink method 



