CHAPTER XIII. 



BACTERIOLOGICAL TECHNIQUE Continued. 



THE CULTIVATION OF BACTERIA. 



IN order to determine the number of living bacteria 

 in any substance and their nature we have to cultivate 

 and isolate them. 



The Most Common of the Nutrient Media Used for the 

 Growth of Bacteria. 



All of these must have, as noted earlier, food con- 

 taining the necessary carbon, nitrogen, and mineral 

 substances in a form easily assimilated and in the 

 proper concentration. The pathogenic bacteria nearly 

 all require for good growth peptone, albumins, and 

 sugar. For each kind the proper food must be found 

 through experimentation, as slight alterations may 

 make a great difference. 



Physicians will find it, as a rule, convenient to 

 purchase their media already prepared from some of 

 the reliable firms that deal in bacteriological products. 

 Special media, such as those employed for isolation and 

 identification of the typhoid bacillus and gonococcus, 

 will be found described along with those bacteria. For 

 those who may wish to make their own, we will de- 

 scribe here those in common use: 



Nutrient Bouillon or Broth. One part of finely chopped 

 fresh, lean meat is macerated in two parts of water and 



