TESTING THE SANITARY CONDITIONS OF MILK 157 



tainted. If it is spongy and full of holes, it con- 

 tains those undesirable organisms that produce gases 

 in the curd and injure it for cheese-making, showing 

 in the form of "floating curds" and "huffy" cheese. 

 The holes are usually small, their common name be- 

 ing "pin-holes." (2) The curd is examined with ref- 

 erence to any marked disagreeable odors that may 

 be present. Some undesirable organisms reveal their 

 presence by smell without making spongy curd. This 

 may, perhaps, be best perceived by smelling of a 

 freshly cut surface of the curd. Offensive odors are, 

 of course, an undesirable indication. Special appara- 

 tus for performing the test is furnished by dairy-sup- 

 ply houses, but pint fruit- jars and other home-made 

 appliances will answer satisfactorily. 



By this method one can learn what particular lot 

 of milk among several is responsible for undesirable 

 fermentations. Moreover, having traced the source of 

 contamination to a single herd of cows, it is easily 

 possible, applying the test to single cows, to ascer- 

 tain which individual or individuals may be the source 

 of trouble. 



Precautions. Two points must be carefully ob- 

 served in carrying out this test : ( i ) The temperature 

 must be kept as near 98 F. as possible, in order that 

 the bacteria may develop as desired. This can be 

 done by keeping the temperature of the water sur- 

 rounding the jars at 100 to 102 F. The tempera- 

 ture must be watched. (2) The thermometer and the 

 knife used should be made not only clean but sterile 

 each time after using in one sample before placing 

 them in another. 



