50 A MANUAL OF BACTEHIOLOGY 



Exercise 68. Study of Micrococcus candicans 



Make cultures on agar and gelatin. Study the microscopic 

 and cultural features. 



Exercise 69. Study of Sarcina lutea 



Make cultures on gelatin, agar, and potato. Study the micro- 

 scopic characters and compare with M. candicans. 



Exercise 70. Study of Bacillus fluorescens liquefaciens 



This organism is common in air and in water. It is one of 

 those commonly present in decaying albuminous compounds. 



Under the microscope note the small rods. In liquids the rods 

 are actively motile. Make cultures on gelatin, agar, and potato. 

 Note the fluorescence developed. Is it imparted to the agar or 

 is it confined to the colony of bacteria ? 



Exercise 71. Study of Bacillus prodigiosus 



This bacillus was formerly classed as a micrococcus. It is 

 quite common and was one of the first to be noticed, because of 

 the conspicuous red pigment it produces on starchy media. 



Under the microscope' note the small rods. Make cultures on 

 gelatin, agar, and potato. 



Exercise 72. Study of Bacillus subtilis (Hay Bacillus) 



This is one of the most wi(Jely distributed of bacteria. It not 

 only occurs in air but also in water, soil, and all sorts of putre- 

 fying liquids if oxygen be present. It is abundant in hay in- 

 fusions. It grows rapidly and forms spores abundantly. Under 

 the microscope study the individual rods and the chains. Make 

 special spore stain, using bacteria from an old culture. One way 

 of obtaining cultures of this organism is to cover finely cut hay 

 with distilled water and boil for a quarter of an hour. Set 

 aside with a loose cover for forty-eight hours. A thick scum 

 will show itself on the surface, composed of B. subtilis whose 

 spores have survived the heat. Make cultures on gelatin, agar, 

 and potato tubes ; also gelatin and agar plates. 



