CHAPTER IV 



PREPARATION OF CULTURE-MEDIA FOR INOCULATION 



We have on a former page described the methods to obtain 

 sterile stock of nourishing media suitable for artificial cul- 

 tivations. Those media which are to be used in a solid 

 state must, before solidification, be contained in test-tubes 

 and small flasks, sterilised and solidified in the manner 

 above described, so as to be ready for establishing cultures — • 

 i.e. for inoculation. The Agar-Agar mixture however can, 

 hke broth, peptone mixture, beef extract solution, and 

 gelatine mixtures, be kept as stock in large flasks. When 

 thus sterile these latter can be decanted when required into 

 a number of test-tubes or small flasks, in which the cultiva- 

 tion is to be carried out. Gelatine mixtures (gelatine and 

 broth, gelatine and peptone, gelatine and beef extract) and 

 the Agar-Agar mixtures, must of course be liquefied over a 

 flame before being ready for decanting. The test-tubes 

 most suitable are about six inches long, and should not be 

 less than about § to f inch broad ; the flasks are of the 

 capacity of one, two or more ounces, and ought to have a 

 neck of compararively good width. The test-tubes receive 

 the fluids for about one and a half to two and a half inches 

 in depth — more (up to four inches) for anaerobic cultures—' 



