New York Agricultural Experimext Station. 45 



examination shows that a majority of these colored points are 

 located on the walls of the small openings left by the incomplete 

 union of the particles of cut curd or by the later formation of 

 gas bubbles. 



These points rarely become visible in cheese under eight days 

 old, and gradually increase in size during the first two or three 

 months. During the latter portion of this time the extension of 

 these spots is probably not due to real growth, but rather to a 

 mechanical spreading of the coloring matter along the surface 

 upon which it has been produced. 



This trouble is most common in spring and fall, appeai'ing in 

 May and disappearing in Octo'ber; while in the case of a badly 

 infected factory it may continue through the summer season. 



The coloring matter does not seem to be in any way harmful 

 to the consumer, and if a trade could be built up in variegated 

 cheese, this might command an increase in price on account of 

 its color. However, the present attitude of the market is quite 

 the reverse, and the presence of these spots means a cut in the 

 price and corresponding loss to the producer. 



The only other trouble in hard cheese coming to our notice 

 \vhich might be confused with the one under discussion is a pink 

 dificolorati'jn of the rind occurring either in isolated spots or in 

 confluent patches. This latter is attributed to mold, and cer- 

 tainly has nothing in common with the genuine " rusty spot," 

 which is confintd to the interior and scattered throughout the 

 mass of the cheese. A peculiarity which will illustrate the dif- 

 ference lies in the fact that when the rusty spots in cheese are 

 brought to the air and light they fade from red through yellow, 

 growing fainter until they finally disappear, while these pink 

 discolorations are formed and continue on the exterior of the 

 cheese, in direct contact with the air and light. 



THE TROUBLE IS CAUSED BY A BACTERIUM. 



From the fact that the spots cannot be seen in the young 

 cheese, but appear later and continue to grow more evident for 



