54 METHODS OF CULTIVATION OF BACTERIA 



gelatin is also " sloped "), and this is ike position in which blood 

 serum is inspissated. Tubes, especially those of the less commonly 

 used media, should be placed in large jars provided with stoppers, 

 otherwise the contents are apt to evaporate". A tube of medium 

 which has been inoculated with a bacterium, and on which 

 growth-has taken place, is called a " culture." A " pure culture " 

 is one in which only one species Js present. The->methods of 



FIG. 12. Tubes of media. 

 a. Ordinary upright tube. 

 FIG. 11. Apparatus which may *- sl(J P ed tube, 



be used for filling tubes. The c - " Dee P " * ube f or cultures of 



apparatus explains itself. The 

 indiarubber stopper with its 

 tubes ought to be sterilised 

 before use. 



obtaining pure cultures will presently be described. When a 

 fresh tube of medium is inoculated from an already existing 

 culture, the resulting growth is said to be a " sub-culture " of 

 the first. Manipulations involving the transference of small 

 portions of growth either from one medium to another, as in the 

 inoculation of tubes, or, as will be seen later, to cover-glasses for 

 microscopic examination, are effected by pieces of platinum wire 

 (Nos, 24 or 27 Birmingham wire gauge the former being the 



