50 REPORT OF THE BACTERIOLOGIST OF THE 
Taking the results on different days, as shown in the above 
table, it will be seen that the positive results were most marked 
on August 5 and 6 and August 23. It so happened that there 
was a sharp outbreak in the factory cheese of August 5 and 6, and 
the samples of those days marked -++- + -++ were completely filled 
with closely-set red points, indicating that these dairies had fur- 
nished, on these days, a heavy starter of Bacillus rudensis. 
Much less discoloration developed in the factory cheese of 
August 21 to 28, and while there was a moderate number of red 
points present in the samples from a considerable number of 
patrons on. these days, the contamination in individual cases did 
not appear to be as heavy as on August 5 and 6. 
The factory cheese of September 4 and 5 was almost entirely 
free from red points, and it will be observed that these were also 
lacking in the test cheeses of these dates. 
The difference in the results 6f August 21 and 23 can be partly 
accounted for on the basis of difference of manufacture. While 
there were good individual cheeses on each day, the formation of 
acid in the cheese of August 21, taken as a whole, was too great. 
The cheeses of August 22 averaged much better in this respect, 
and those of August 23 were, everything considered, the best 
which we have succeeded in making. 
It will be further observed that in no case did any one patron 
respond positively to four or more consecutive tests. This failure 
to respond in some cases may be ascribed to lack of success in 
preparing the small cheese, but these results accord well with 
our observations in the factory, to the effect that the introduc- 
tion of Bacillus rudensis, at least in appreciable quantities, 
occurs only spasmodically. <A failure to respond in three or 
more consecutive tests is shown in a number of instances. 
WHAT IS THE SOURCE OF THE CONTAMINATION? 
The presence of rusty spots in the cheese points to the factory 
as the source of supply of Bacillus rudensis. 
The curd mill is a utensil peculiarly difficult to clean in the 
ordinary way, and our experience at Factory Number One indi- 
