Bacterial counts on kettle contents during manufacture showed that, of the starter bacteria, only Streptococcus thermophilus increased in numbers, while Lactobacillus casei or L. bulgaricus and Propioni-bacterium shermanii did not increase and sometimes decreased. Gas-forming bacteria of the colon-aerogenes group showed little or no increase when there were comparatively few in the original kettle milk; but when they were in large numbers they showed a marked increase during the processes in the kettle. Strep. lactis usually increased in the first part of the kettle process, but was stopped by cooking temp. Under normal conditions there was a small decrease in pH of kettle contents, due chiefly to physico-chemical causes.