Four cows, all giving milk low in solids-not-fat, were used for the experiment:

1. The change from winter rations to pasture produced a decided increase in the solids-not-fat percentage and milk yield.

2. Well-balanced rations fed to the cows during two lactations showed a small rise in the milk yield and solids-not-fat during the second lactation, but did not increase the solids-not-fat to above the 8·50 per cent, limit.

3. Feeding a high protein ration of albuminoid ratio 1:2·76 produced no change in milk yield or casein, decreased the solids-not-fat and lactose, and increased the total milk nitrogen and albumin and globulin nitrogen.

4. Feeding a high carbohydrate ration of albuminoid ratio 1:9·90 did not affect milk yield, fat or ash, but decreased slightly the solids-not-fat.

In the ruminant, the main tertiary nitrogenous metabolite of all the tertiary nitrogenous bases examined is trimethylamine oxide. Small traces of trimethylamine and insignificant traces of mono- and dimethylamine also occur in cow's urine. The nitrogen of simple bases (trimethylamine and trimethylamine oxide) is almost quantitatively and rapidly excreted as trimethylamine oxide. With betaine, choline and the methyl ester of dimethylaminoacetic acid, only from 14 to 43 per cent, of the nitrogen is excreted as trimethylamine oxide, the amount so excreted depending on the level of nitrogen intake, the nature of the base fed and the degree of accommodation of the animal to the base fed.

The rates of excretion of the tertiary metabolite show well-defined peaks depending on the nature and amount of the base fed. The feeding of 100 g. of betaine would show a peak of excretion at about 4½ hours after feeding. The importance of the time interval between feeding and milking is discussed from this aspect. No unchanged betaine was be detected in the urine.

1. A method has been described for obtaining milk anaerobically from the udder.

2. A technique for transferring anaerobically drawn milk to an electrode vessel for the determination of oxidation-reduction potentials under anaerobic conditions has been described.

3. A technique for transferring anaerobically drawn milk to a van Slyke apparatus for gas analysis has been described.

4. The total CO2 of cows’ milk is about half that of their blood plasma.

No sulphydryl compound in free solution could be found in cow's milk. It is suggested that the positive nitroprusside test obtained in milk treated with sodium cyanide is traceable to the cystine in the protein complex.

1. Bacteria may play but an insignificant part in the reduction of methylene blue in milk, though their de-oxygenating effect may be of influence in the commercial application of the test.

2. Milk as it exists in the udder, or milk drawn anaerobically, reducesmethylene blue almost instantaneously, whereas the same milk exposed to oxygen will usually take more than 10 hours to reduce.

3. The oxidation-reduction potential of anaerobically drawn milk is much lower than the same milk exposed to oxygen, and in accordance with its behaviour toward methylene blue.

4. Evidence is given for the presence of a redox system, present in low concentration, as responsible for the reduction of methylene blue.

5. Although the addition of small amounts of cysteine or glutathione to milk leads to the reduction of methylene blue, their absence from milk excludes them as possible factors in the normal reduction.

6. The possibility that lactoflavin may furnish the redox system is suggested.

7. The reduction of methylene blue in milk is catalysed by light in the visible spectrum.

1. The application of the method of Somogyi to the determination of the reducing sugar in milk, with a precision of ± 0·36 per cent., is described.

2. Washed yeast does not ferment lactose and does not add reducing material to tungstic acid nitrates.

3. The reducing substance in milk removable by yeast can be determined with an accuracy of ± 3 per cent.

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.

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.