96 BACTERIOLOGY. 



labelled, and, if necessary, placed in the incubator, 

 and the results watched from time to time. Instead 

 of bouillon liquid blood serum may also be em- 

 ployed in this form of cultivation. If it be required 

 to preserve the drop cultivation as a microscopic 

 preparation, the cover-glass is gently lifted off and 

 allowed to dry. Any vaseline adhering to the 

 cover-glass should be wiped off, and the cover-glass 

 can then be passed through the flame and stained 

 in the usual manner. 



Moist - Chambers. Unless drop-cultures are 

 very carefully prepared, they are liable to dry up, 

 if kept for examination for several days. Many 

 therefore prefer employing a moist-chamber. There 

 are several different forms in use. 



The drop-culture slide may be converted into a 

 moist-chamber by having a deep groove cut round 

 the circumference of the concavity. This groove is 

 filled with sterilised water by means of a pipette. 

 A ring of vaseline is painted with the camel's-hair 

 brush outside the groove, and the cover-glass with 

 the drop-cultivation is inverted and placed over the 

 concavity. This form is very useful, as the slide 

 can be easily cleansed and effectually sterilised by 

 holding it in the flame of the Bunsen burner. 



A very simple form of moist-chamber which may 

 be used in some cases, but possesses the disadvan- 

 tage of not admitting of sterilisation by heat, may 

 be constructed as follows* : 



* Schafer's Course of Practical Histology. 1877. 



