242 



udder is diseased, as in tuberculosis, infectious mastitis, etc., 

 the milk as it comes from the udder may contain tubercle 

 bacilli or the other infectious germs. 



Milk being a good food for bacteria, a great majority begin 

 to grow and multiply as soon as they get into the milk. This 

 is especially the case if the temperature of the milk is not 

 reduced below 45 degrees F. in a short time after the milk is 

 drawn from the udder. Very few germs can grow at such a 

 low temperature, and^ those that can grow under such a con- 

 dition will do so very slowly ; many times the milk may be 

 used before these low temperature germs can seriously 



injure it. 



Determining the number of bacteria in a cubic centimeter 

 of milk is called a quantitative bacteriological analysis. 



Determining the different kinds of bacteria and their peculiar 

 characteristics is called a qualitative bacteriological analy- 

 sis. Many times these analyses are very difficult, tedious, 

 and expensive. The most important conclusion to be drawn 

 from the number of bacteria in a given quantity of milk is 

 that, as a rule, the greater the number of bacteria the greater 

 the filth in the milk and in the handling of the milk. Gro- 

 tenfelt found that samples of milk drawn "in a pasture on a 

 fresh, somewhat damp summer morning showed the following 

 average results as regards their bacterial content:" 



Immediately after drawing from the udder, 10 bacteria per 

 c.c. of milk; one half hour after milking, 88 bacteria per c.c; 

 two hours after milking, 1,530 bacteria per c.c. These num- 

 bers are very small, and show that the milk was as nearly 

 free of bacteria as it is practicable to obtain it. The milkirg 

 was done in a clean, dewy pasture, surrounded by woods, 

 where the air was still. These were clean conditions. Gro- 

 tenfelt further says that a sample of milk drawn in a filthy 

 and dark cow stable showed, in three fourths of an hour after 

 milking, "not less than 670,000 bacteria per c.c." "The bac- 

 terial content of three samples of milk taken on thiee consec- 

 utive days from this stable did not vary much— the analyses 

 showing the following average figures per c.c : '5 30,000 ; 560,- 

 000, and 780,000." 



