1. Agglutinating type sera were prepared in rabbits for fourteen representative strains in a collection of sixty-eight group N (‘lactic’) streptococci.

2. Common type antigens, distinct for each named species, were found in strains of Str. lactis (inhibitory varieties), Str. diacetilactis and Str. cremoris.

3. Certain individuals in each of the named ‘groups’ contained additional heterologous antigens, some of which were identical to heterologous (but not the common) antigens in strains of other groups.

4. Quantitative differences in the representation of common antigens were also found.

5. Str. lactis OJ and Str. cremoris HP were shown to be mirror images of each other so far as their type antigens are concerned, containing two common type antigens in inverse proportions of 4:1 respectively. Str. lactis OJ possesses the ‘cremoris group’ type antigen, and the implications of this observation are discussed.

In the determination of aldehyde values of slightly oxidized butterfat samples by Schibsted's method, the colour of the butterfat prevents accurate matching with the colour standard. Interference by butterfat colour is eliminated, and more accurate results are obtained if the colour is measured in a photoelectric colorimeter at a wavelength of 510 mµ. A small constant correction for the absorption by butterfat at this wave-length may be made.

During the course of some earlier work (not yet published) on the physical properties and the quality of butter, the writer noticed that occasionally a sample was encountered which appeared to be very slightly rancid after only 3 weeks' storage in a cold store. These samples were observed to have a low electrical resistance, and to be of inferior texture, usually exhibiting some free moisture droplets when freshly cut. It appeared likely that there might be some definite relation between the resistance, the texture, and the keeping quality of butter. At the time of these experiments, however, the phenomenon only occurred with a few samples of one type of blended butter. The present note describes an experiment designed to explore the possibility that the relationship might be more general, and apply to other types of butter.

The apparent lytic effect of a newly formed (‘nascent’) streptococcal bacteriophage on streptococcal strains not normally lysed by the phage was shown to be actually an inhibitory action produced by high concentrations of the phage. The inhibitory effect was exhibited by stock preparations of the phage, used in sufficient concentration, and there was no need to postulate a special potency for the phage in its ‘nascent’ form. The inhibitory effect of phages on heterologous organisms was found to be a widespread phenomenon among strains of Streptococcus cremoris and Str. lactis. It became apparent only when larger proportions of phage than the traces normally used for lytic tests were employed.

Supplementation of a typical Danish winter ration with 2 g. of DL-α-tocopherol acetate per cow per day did not result in an increased yield of milk or milk-fat. The keeping quality of the butter was practically uninfluenced or possibly slightly reduced by the supplementation. The supplementation caused a rise in the tocopherol content of the butter from 10 to 12µg./g. in the unsupplemented group to 23–26/µg./g. in the supplemented group. After the experimental period the amount of total tocopherol in the butter decreased rapidly. It increased again when the cows went to pasture.

Butter-fat obtained from the unsupplemented group with 9·6–13·2µg. tocopherol/g. and from the supplemented group with 27·3–31·2µg. tocopherol/g. did not produce encephalomalacia in chicks when incorporated at a level of 30% instead of lard in a suitable test diet, but the amount of tocopherol present, especially in the butter-fat from the unsupplemented group, was not sufficient to prevent white striation of breast muscles in chicks under the same conditions.

1. Two spray-dried milks, one separated and one whole milk, have been stored at 25°C. for 48 and 103 weeks respectively at relative humidities ranging from 0 to 100%. At high humidities (80–100% r.h.) a rapid fall in the numbers of bacteria was followed by rapid growth of bacteria and by overgrowth by moulds. At relative humidities below 80% the number of surviving bacteria increased with decreasing humidity to maximum survival at about 10% r.h. and then tended to fall again towards 0% r.h.

2. The changes in the distribution of the different types of bacteria in the dried milks at different relative-humidities are discussed.

3. Maximum survival at 5–15% r.h. has been confirmed with pure cultures (dried in milk) of a Streptococcus and a Micrococcus originally isolated from dried milks.

4. The marked loss of viability of bacterial spores noted in dried milks stored over P2O5 or concentrated H2SO4 has been confirmed for a dried suspension of the spores of a typical strain of Bacillus subtilis.

A method for determining the size distribution of fat globules in cream has been described. A thin film (20 μ) of the diluted cream on a microscope slide is preferred to a deeper preparation (0·1 mm.) in a counting chamber in which rise of fat globules to the upper surface is necessary for easy observation. The latter method is less convenient and can give too low an estimate of the proportion of the smallest globules (1 μ and under).

Cream should be diluted 1 in 50 and the concentration of gelatin in the dilution should be sufficient (4–6%) to give a rapid gel formation. The mixture should be cooled till the gelatin thickens before being transferred to the slide if it is to give the most uniform distribution of globules.

It is shown that Vacreator-treatment of cream causes a considerable increase in the proportion of fat present as globules less than 2 μ and a small increase in the proportion present as globules over 10 μ in diameter. Flash-pasteurization, on the other hand, causes a slight decrease in the proportion of fat present as small globules and a considerable increase in that present as large globules.

Butter from flash-pasteurized cream contains numerous large fat globules and fat aggregates, while butter from Vacreator-treated cream contains few large globules. It is suggested that the more uniform subdivision of fat in butter from Vacreator-treated cream explains why butter from Vacreator-treated cream is superior in texture to butter from flash-pasteurized cream.

1. Eighty-three experimental washed curd cheese were made to investigate the effects of variations in the washing and scalding processes upon the qualities of texture and eyehole formation.

2. Texture was influenced markedly by the amount of washing received by the curd, and a ‘half-wash’ procedure which gave the most satisfactory results is described. Good texture was also favoured by low scalding temperatures (98–107° F.) and short scalding times (8–20 min.).

3. Eyehole formation was affected by scalding time (particularly exceeding 30 min.) rather than temperature.

4. The best combination of conditions appeared to be a ‘half wash’ with scalding at 103° F. for a period not exceeding 25 min.

5. Large cheese moulds (30 lb.) failed to yield a satisfactory product and their use is not recommended.

The accumulation of fat in a rubber liner occurs mainly in two regions, the mouthpiece and the portion of the barrel in contact with the teat. It is suggested that the mouthpiece is attacked by body fats and udder salves mainly, whereas the barrel absorbs milkfats from milk trapped between the rubber and teat. The accumulation of fat increases linearly with the number of milkings performed.

The loss of milking efficiency is connected with the stiffness of the rubber compound, and this latter property decreases linearly with the number of milkings. The length of service of a liner on the farm is shown to be largely dependent on the individual farmer and his standards of efficiency and cleanliness.

The presence of fat in rubber leads to an enhanced rate of oxidation and consequent loss of physical properties. This has been confirmed in practice. An increase in the tension of a liner increases the rate of swelling and the souring of milk on rubber gives a similar result. The use of detergents has no direct deleterious effect on the physical properties of rubber. They are not effective in removing fat from below the surface layers. The occurrence of ozone-cracking of parts of milk liners or tubing, which are under tension, is discussed and the use of waxes in the compound as a remedy is described.

Results of a survey of the carotene and vitamin A contents, and of the vitamin A potency, of New Zealand butterfat and butter, are presented. The butter samples were drawn from twenty representative commercial factories at fortnightly intervals over three successive years (1946–8). The survey covers the analysis of 1517 samples of fresh butter and 670 samples of stored butter.

There were uniform and regularly recurring seasonal variations in both carotene and vitamin A contents of butterfats from all North Island districts. Maximum values were found in the late-autumn/winter/early-spring, and minimum values in the late-summer/early-autumn butterfats. The seasonal trends were thus distinctly different from those which have been reported for northern hemisphere butterfats, for which the maximum values are commonly found during the summer grazing period.

The seasonal variations in carotene and vitamin A contents of South Island butterfat were less marked and less consistent than those in the corresponding values for North Island butterfat.

1. Cultures of Str. faecalis, L. plantarum and a strain of Leuconostoc, when added to cheese milk, all brought about an increase in Cheddar flavour intensity in the resultant cheese.

2. Examination of the cheeses for tyramine content showed that the formation of the amine bore no relationship to the increases in flavour intensity. The production of tyramine appeared to be merely incidental in the cheese-ripening process.

3. A survey among the lactic acid bacteria disclosed only one species containing a significant amount of the L( – )-tyrosine decarboxylase enzyme—L. brevis. This species added to cheese milk causes an objectionable ‘yeasty’ flavour in the final cheese.

A general preliminary description is given of a uniformity trial with twin cattle, the object of which was to study sources of variation within pairs by comparing one-egg and two-egg twins with pairs of contemporary half-sibs. Problems relating to equality of treatment and accuracy of diagnosis are discussed.

Variations in the unsaturated acid constituents of butterfat samples from the Manawatu district of the North Island of New Zealand over the months October to April were studied by the spectrophotometric technique, applied both before and after alkali isomerization of the fat.

The seasonal variations in the iodine values of the butterfats were found to be closely related to the changes in oleic acid content. Conjugated dienoic acids, though present in relatively small amounts, showed a somewhat similar seasonal trend in values to oleic acid. The results for percentage content of non-conjugated dienoic acids were low, and they fluctuated considerably from month to month. Conjugated trienoic and tetraenoic acids were absent or present only in traces. Small but fairly consistent quantities of nonconjugated trienoic and tetraenoic acids were found in all samples.

Large-scale manufacture of washed curd cheese has not yet been attempted in Britain. There seems to be no obvious obstacle, and the production of a good washed curd cheese would satisfy several present-day requirements. It is popular with consumers and would be an alternative to the usual standard varieties; it has certain economic advantages in manufacture and excellent properties for retail sale. In addition, low acid whey is in considerable demand as an important ingredient of certain proprietary brands of infant foods; such whey is not readily obtainable by normal cheese-making, but is produced during the manufacture of this cheese.

1. Results from a uniformity trial with fifteen pairs each of one-egg and two-egg twins and pairs of half-sibs are described.

2. Intra-pair variance in age at the first observed heat was less for the one-egg than for the other pairs but not significantly so. The slowest growing pairs showed delay in onset of heat.

3. 71·8% of the intervals between heats shown by unserved heifers were 17–27 days in length. No genetic variation and no individuality could be detected in either this character or the number of services per conception.

4. The variance in the gestation period was less within the one-egg than within the other pairs but not significantly so.

The two substances previously assumed to be necessary for the bacteriostatic action of raw milk have been concentrated and separated from one another. Electrophoretic experiments have shown that the preparations, though highly active, are still far from pure and that it should be possible to obtain material of much greater potency.

The pulsator mechanism of the double-action milking machine causes the rhythmical expansion and collapse of the rubber teat-cup liner during milking by alternately applying a partial vacuum (usually 13–15 in. Hg) and admitting atmospheric air to the space between the rubber liner and the teat-cup shell. The inside of the liner is subjected to continuous partial vacuum.