THE CORNELL READING-COURSES 



square inches; a pail with 1 2-inch top has an opening of 113.04 sqi 

 inches; one with lo-inch top has an opening of 79.79 square inches; a 



with an opening of 6 inc 

 in diameter has an exj 

 of 28.26 square inches. 



" Milkers should get 

 the habit of using the 

 top pail, as it is one 



FIG. 29 Diagram showing size of openings in easiest of all ways for 

 various kinds of milk pails. The large circle 



at the left represents the common milk pail. m g the number OI bad 

 The others show the perpendicular exposure in that fall into milk. 

 the new kinds of pails 



6. Contamination by flie. 



A fly or a bit of hay or straw or a piece of sawdust or a small hair, 

 carry enormous numbers of bacteria into milk as is shown by the fc 

 ing experiments : 



"A living fly was introduced into 500 cubic centimeters of sterile 

 The milk was shaken one minute and then it contained 42 bacteria 

 cubic centimeter. After 24 hours at room temperature, it contai 

 765,000 bacteria per cubic centimeter, and after 26 hours 5,675,000. 



7. " Dirt in the milk. A piece of hay about two inches long was pla| 

 in 500 cubic centimeters of sterile milk. The milk was shaken one mi 

 and it then contained 3,025 bacteria per cubic centimeter. After 24 h 

 at room temperature it contained 3,412,500 bacteria per cubic centime 



" One piece of sawdust from the stable floor was put into 500 

 centimeters of sterile milk. The milk was shaken one minute and 

 bacterial content was then found to be 4,080 per cubic centimeter. 

 24 hours at room temperature it was 7,000,000 per cubic centimeter. 



"A hair from a cow's flank was put into 500 cubic centimeters of s 

 milk. After shaking the milk for one minute it contained 52 bacteria 

 cubic centimeter. After 24 hours at room temperature it contained 55, 

 per cubic centimeter, and after 36 hours over 5,000,000 bacteria per 

 centimeter." 



REFERENCES FOR FURTHER STUDY 



Belcher, S. D. Clean milk. Hardy Publishing Company, New Yor 



Conn, H. W. Agricultural bacteriology. P. Blakiston's Son & Co. 

 The story of germ life. D. Appleton & Co., New Y 

 Bacteria, yeasts, and molds in the home. Ginn & 

 Practical dairy bacteriology. Orange Judd Com 

 New York 



Elliott. Household bacteriology. American School of Home Econ< 

 Chicago 



Lipman. Bacteria in relation to country life. The Macmillan Compa] 



Marshall. Microbiology. P. Blakiston's Son & Co. 



