192 LABORATORY GUIDE IN BACTERIOLOGY 



salt-rising bread dough, and carbon jiioxid is liberated, 

 which causes the bread to rise. 



SECTION 6 

 A STUDY OF TORULAE 



Experiment i — 



1. Transfer from laboratory cultures to wort agar. 



2. Make stains, and transfer to all the other media. 



3. Make descriptions of these organisms, and note 

 the differences from yeasts. 



Experiment 2 — 



1. Prepare three plates of wort agar. 



2. Expose these to the air in different places. 



3. Incubate at 25° C. 



4. After 48 hours fish for torula colonies, transfer 

 these to all the media, prepare stains, and describe the 

 cultures. Inoculate fermentation tubes with carbo- 

 hydrates, and inoculate gypsum blocks. Some torulae 

 produce gas froin lactose; the true yeasts do not. 

 Torulae do not form spores. 



SECTION 7 



A STUDY OF ACETIC-ACID BACTERIA 

 EXERCISE 1 



1. Secure some old vinegar with a film on top. 



2. Prepare a suspension of the film in sterile water. 



3. Plate out in wort agar, and incubate at 25° C. 



4. Transfer the colonies to slant agar. 



5. Inoculate flasks containing about 50 c.c. wort and 

 I per cent alcohol with the cultures. 



