30 APPLIED BACTERIOLOGY FOR NURSES 



The freshly planted culture is now placed in the 

 incubator. This is a kind of oven whose walls are filled 



Fig. 12. Streptococcus pyogenes, culture on agar. Slightly en- 

 larged (Williams). 



with water, and whose interior is kept at a uniform tem- 

 perature by means of a lamp or gas flame controlled by 



