BACTERIOLOGICAL TECHNIC 53 



be obtained successfully by electric devices. For class use large 

 incubators are constructed on similar principles, with a number 

 of separate compartments for the accommodation of large num- 

 bers of students. 



SECTION 9 

 METHOD OF DESCRIBING CULTURES 



The following method of describing cultures should 

 be carefully studied, and each suggestion should be 

 considered in the description. It is of prime impor- 

 tance that cultures should be closely observed, in all 

 media, and accurately described and sketched, as this 

 is the only method which furnishes the proper means 

 of studying and determining the different species of 

 bacteria. By keeping this scheme in sight while mak- 

 ing a description, it will be possible after some practice 

 to make perfect descriptions without its aid. After 

 growth has taken place the culture should be compared 

 with a sterile tube of the same batch of culture medium. 



I. Morphological characters of bacterium. 

 Size. 



Facility and mode of staining. 

 Gram stain. 



Special staining qualities. 

 Motility. 



Present or absent. 



Sluggish or active movement. 

 Flagella present or absent. 

 Capsules present or absent. 

 Spores present or absent. 

 Involution forms. 



