120 VACCINE AND SEKUM THERAPY 



has modified to a greater or less extent its biological 

 characters (resulting in the establishment of a number 

 of " strains" of that organism), the best results will 

 be obtained by utilising an autogenous rather than a 

 stock vaccine. 



In some cases the preparation of an autogenous 

 vaccine is a matter of great difficulty, if not of 

 impossibility, owing to the difficulty of isolating the 

 responsible organism ; but it should always be 

 attempted, although a stock vaccine may be utilised 

 during the interval. 



The organism must be as virulent as possible, and 

 to retain this character the subcultivations used in 

 the preparation of the vaccine must not be far re- 

 moved from the body of the patient. In other words, 

 the isolation of the bacterium from the morbid 

 material must be effected as rapidly as possible and 

 in as few generations as is consistent with obtaining it 

 in a state of purity. Next, the particular subcultiva- 

 tion intended for the production of the vaccine must 

 be cultivated under *' optimum " conditions. 



The actual process of preparing a vaccine is briefly 

 as follows : The organism responsible for some given 

 infection, having been isolated from the lesion exist- 

 ing in the patient and identified, is planted upon a 

 suitable medium, and is incubated under optimum 

 conditions for such period of time as experience shows 

 is calculated to yield the maximum number of living 

 vigorous bacteria. At the end of the cultivation 

 period the growth is examined visually to determine 



