220 BACTERIA 



has been to divide a certain quantity of cream into two 

 parts, one part inoculated with the culture and the other 

 part left uninoculated. Both have then been ripened under 

 similar conditions, and churned in the same way ; the differ- 

 ences have then been noted. It is interesting to know that, 

 as a result of the year's experience, creameries have been 

 able to command a price varying from half a cent to two 

 cents a pound more for the " culture " butters than for the 

 uninoculated butters. The method advised in using this 

 pure culture is to pasteurise (by heating at 155 F.) six 

 quarts of cream, and after cooling to dissolve in this cream 

 the pellet containing bacillus No. 41. The cream is then 

 set in a warm place (70 F.), and the bacillus is allowed to 

 grow for two days, and is then inoculated into twenty-five 

 gallons of ordinary cream. This is allowed to ripen as 

 usual, and is then used as an infecting culture, or " starter," 

 in the large cream vats in the proportion of one gallon of 

 infecting culture to twenty-five gallons of cream, and the 

 whole is ripened at a temperature of about 68 F. for one 

 day. The cream ripened by this organism needs to be 

 churned at a little lower temperature (say 52-54 F.) but to 

 be ripened at a little higher temperature than ordinary cream 

 to produce the best results. Cream ripened with No. 41 

 has its keeping power much increased, and the body or 

 grain of the butter is not affected. More than two hundred 

 creameries in America used this culture during 1895, and 

 Professor Conn reports that this has proved that its use for 

 the production of flavour in butter is feasible in ordinary 

 creameries and in the hands of ordinary butter-makers pro- 

 vided they will use proper methods and proper discretion. 



Bacteria in Cheese -making. The cases where it has been 

 possible to trace bacterial disease to the consumption of 

 butter and cheese have been rare. Notwithstanding this 

 fact, it must not be supposed that therefore cheese contains 

 few or no bacteria. On the contrary, for the making of 



