1. The importance of a rapid and simple test for the diagnosis of mastitis in cows is a question which has attracted considerable attention on the part of many workers. One such test based on the determination of chlorine in milk by a rapid method has been advocated recently by Rosell.

2. The authors of this paper have made a careful examination of this method and compared the results obtained on samples of milk with those given by other methods known to yield reliable and reasonably accurate results.

3. The direct titration of chlorine in milk with silver nitrate solution, without the removal of proteins, invariably gives high results, and, moreover, a satisfactory end-point is difficult to obtain.

Several defects in canned cream after some months' storage have been classified: (1) “purpling” of the can, due to a film of tin sulphide, (2) pitting of the can, associated with (3) formation of black patches and of black specks in the body of the cream, consisting of ferrous sulphide, stannous oxide or both.

“Purpling” is produced by excessive time and temperature of sterilization, owing to the liberation of active sulphur compounds which attack the tin. Addition of sodium bicarbonate up to 5 g. per gallon has, if anything, a slightly beneficial effect.

The occurrence and isolation of bacteriophages from cultures of lactic streptococci (“starter cultures”) is described. Aeration of the milk in which the phage-infected cultures are grown is shown to have a stimulating action on the development of the phage. The characteristics of phages for lactic streptococci are described.

A survey has been made of the flora of foremilk and rennet extract with special reference to acid-proteolytic types. In both instances, acid-proteolytic cocci were isolated of the type Staphylococcus sp., Micrococcus caseolyticus, M. freudenreichii, Streptococcus liquefadens. Older rennet samples were found to be more productive of proteolytic cocci than either the fresh rennet or the foremilk. Many of the isolated cultures from rennet and from the foremilk failed to show any obvious peptonisation in milk, but yet were capable of liquefying gelatin. These strains may aid in the final breakdown of splitprotein products in a medium such as ripening cheese. The isolated acidproteolytic types were capable of considerable casein degradation in milk. In conclusion, it appears that the foremilk and rennet extract contribute a number of acid-proteolytic organisms to cheese, and that these types may aid in the ripening process.