84 



BACTERIOLOGY FOR NURSES 



cow's udder and flanks will mean a considerably lower bacterial 

 count. Milk obtained by the cleanest methods may contain 

 only a few hundred bacteria per c.c. when drawn ; collected with 

 less care it may contain several thousand, and, unless promptly 

 cooled, the number soon mounts to millions. An excessive number 

 of bacteria, therefore, is an indication that milk is dirty or old or 

 that care has not been taken to keep it cool. The following table 

 illustrates these points well. 



TABLE I 1 



Milk collected under the best conditions possible. Bacterial 

 content at commencement of test 3000 per c.c. 



TABLE II 



Milk collected under ordinary conditions. Bacterial content 

 at commencement of test 30,000 per c.c. 



Germicidal Property. Freshly drawn milk appears to have a 

 slight germicidal action. If samples are examined every hour 

 the colonies at first decrease in number. Soon, however, this 

 property disappears and there follows a continuous and sometimes 

 rapid increase. At temperatures under 10 C. the effect may be 



1 Adapted from Park and Williams, "Pathogenic Microorganisms," 1917, 

 p. 634. 



