902 



Rural School Leaflet. 



parts with which the hands will come in contact while milking. Now 

 rinse your own hands in the clean water, and dry them on the towel. 

 Now milk the cow in the clean milk pail, and take a sample into the 

 other bottle, as before. Cover these bottles by tying a piece of clean 



Fig. 37. — Figure on the left: Petri plate exposed two minutes out of doors, contains 

 six colonies. Aliddle figure: Petri plate exposed two minutes in barn, contains 

 III colonies. Figure on the right: Petri plate exposed two minutes iinder cow 

 being milked, contains i ,800 colonies. These show the relatively large numbers 

 of organisms found on the body of the cow. If these fall into the milk they 

 grow and cause it to spoil rapidly. 



paper over them, and set them away together. Watch the two samples 

 carefully, and determine which one curdles first, and how much differ- 

 ence there is in the time of curdling. Repeat this exercise several times 

 until you find which sample normally curdles first. 



Write your results to this department, and ask for an explanation 

 of your results if they are not perfectly clear to you. 



POINTS TO BE SPECIALLY NOTED IN MAKING THE BABCOCK 



TEST 



H. E. Ross 



1. Be sure to mix the sample of milk thoroughly before drawing 

 it out with the pipette. 



2. When measuring a sample of milk with the pipette keep the 

 index finger dny\ 



3. When measuring a sample of milk keep the mark on the pipette 

 on a level with the eye. The same precaution should be observed 

 when reading the per cent of fat after the test is completed. 



4. Do not try to measure a sample of milk by tr\'ing to draw the 

 milk just to the mark on the pipette. Draw the milk above the mark, 

 as directed. 



