New YorRK AGRICULTURAL EXPERIMENT 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, appearing in 
May and disappearing in October; 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 
which might be confused with the one under discussion is a pink 
discoloratig¢n 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 confined 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 
