32 



the tubes remain perfectly white, whereas cylinders made 

 direct from the raw potato will frequently become discol- 

 ored by the subsequent heating. 



The inoculation of the sterilized potato tubes is easily 

 done. If it is desired to obtain dilution cultures, that is, 

 colonies, this can best be accomplished by making several 

 parallel streaks on the surface of the potato with the end 

 of the platinum wire, if necessary repeating the inocula- 

 tion in two or three tubes, using the same wire. 



When transplanting a pure culture, as a portion of a 

 colony, a single streak should be made along the middle 

 of the inclined potato. 



LABORATORY WORK. Make^streak cultures from the 

 colonies of the bacteria which have been studiedthus far. 



