i6o HOUSEHOLD BACTERIOLOGY 



MEETING IV 



(Study pages 49-62) 



Work of Bacteria 



Fermentation and putrefaction. 



References: The Story of Germ Life, by H. W. Conn. Chap- 

 ters II III, IV. (350., postage 6c.) 



Bacteria, Yeasts, and Molds, by H. W. Conn. 

 Chapters IX-XIII. ($1.00. postage IDC ) 



Our Secret Friends and Foes, by Percy F. Frank- 

 land. Chapters IV, V. ($1.25, postage i2c.) 



See also U. S. Government Bulletins. 



MEETING V 



(Study pages 63-96.) 



Harmful Dust Plants 



(a) Perform the experiments outlined on pages 64-66. 



(b) Boil a pint of milk 15 minutes. Pour into bottle 



which has been boiled in water the same time. Close 



with cork which has also been boiled. 



Pasteurize an equal portion (bottle and cork as above). 

 Keep this at about 155 F. for 15 minutes. Keep both 

 under same conditions. Test each day with blue litmus 

 paper. Note first trace of acid. Test by smell and 

 note first signs of coagulation. Compare results in time. 

 When opening, expose as little as possible to dust. Do 

 not lay cork down or touch lower part with fingers. If 

 cork is handled or exposed to more dust, boil again. 

 While cork is out, lay a clean wet cloth over mouth of 

 bottle. 



References: Dust and Its Dangers, by T. M. Prudden. 

 Chapters VI, VII, VIII. (750., postage 6c.) 

 The Story of Germ Life, by H. W. Conn. Chapters 

 V, VI. (35C., postage 6c.) 



