268 GENERAL MICROBIOLOGY 



methods have been employed as a rapid means of setting 

 bacteriological milk standards? 



Of what value are bacteriological milk standards and 

 analyses? 



15. Give your results in detail and point out any prac- 

 tical applications. 



REFERENCES 



BREW, JAMES D.: A Comparison of the Microscopical Method and 



Plate Method of Counting Bacteria in Milk.' Bui. 373, N. Y. 



Agr. Expt. Sta., Geneva, Feb., 1914. 

 MARSHALL: Microbiology, pp. 293-296, 331-333. 

 LOHNIS: Laboratory Methods in Agricultural Bacteriology, pp. 



62-65. 

 SAVAGE: The Bacteriological Examination of Food and Water (1914), 



p. 85-89, 92, 95-99. 



WARD: Pure Milk and the Public Health (1909), pp. 126-128. 

 ERNST: Milk Hygiene; translated by Mohler and Eichhorn (1914), 



pp. 24-31. 

 FROST, W. D.: A Microscopic Test for Pasteurized Milk. Jour. Am. 



Med. Assn. Vol. LXIV, No. 10, p. 821 (1915). 



EXERCISE 2. THE DETERMINATION OF THE BACTE- 

 RIAL CONTENT OF MILK IN THE UDDER 



Apparatus. Several large sterile test tubes; four 

 sterile Petri dishes; 99 c.c. dilution flasks; sterile 1 c.c. 

 pipettes; tubes of sterile litmus milk; four tubes litmus 

 lactose agar. 



Method. 1. Wash off the end of the teat very care- 

 fully with a solution of mercuric chloride, 1 : 1000; allow 

 it to dry till the surplus solution has disappeared and 

 only sufficient moisture remains to make the cells and any 

 dirt adherent. 



2. Secure a sterile cotton-plugged test tube, remove 

 the cotton pliig with the little finger and, while holding the 

 mouth of the tube as near the end of the sterilized teat as 

 possible and inclining the tube toward the horizontal posi- 

 tion as far as feasible, milk the tube half-full. 



