1. Observations on five animals indicate that the teats of immature castrated male goats grow isometrically. Less extensive data on three animals allow of the tentative conclusion that the same is true of immature normal males. In the male goat therefore teat growth appears to be uninfluenced by the testes.

2. Administration of diethylstilboestrol or its dipropionate to normal or castrated immature male goats causes the teats to grow allometrically for a time.

3. No externally visible udder growth occurred even when oestrogen treatment was prolonged for periods of over a year and was supplemented by progesterone or ethinyltestosterone. Whole mounts of glands from treated animals indicated that some mammary growth had occurred. In two cases microscopic examination showed the presence of alveoli. No explanation can be offered of the failure to develop the udder in the male goat experimentally.

4. Endocrine activity of the ovary as evidenced by a change from isometric to allometric teat growth often manifests itself in the young female goat at an early age. In one case allometric teat growth was in progress at 41 days of age. During the allometric phase the data agree with the simple allometric law.

5. During the rutting season following its birth, teat growth ceases completely in the female goat; allometric growth is resumed when the rutting season ends. It therefore appears that the corpus luteum inhibits teat growth.

6. Administration of diethylstilboestrol or its dipropionate (by inunction of the udder region) causes, in the virgin female, an increase in the rate of teat growth accompanied by udder growth.

1. Defining sensitivity as the power of discriminating significantly between milks of different bacterial constitution the plate count is slightly less sensitive than the methylene-blue test observed every 5 min. and slightly more sensitive than the latter observed every half-hour.

2. The logarithm of the plate count is, in our opinion, the correct measure to use. Its coefficient of variation is slightly less than that of the methylene-blue test observed every 5 min.

3. The plate count as formerly used and the methylene-blue test as now used agree in grading in over 80% of cases.

4. Two samples whose reduction times differ by 30 min. are not significantly different. Such a difference is only significant if the result is based on the mean of duplicate tests with 5 min. observations or of triplicate tests with half-hourly observations.

5. Provided transit hazards are eliminated and standard technique is very carefully observed, there is no significant difference in results from different laboratories by either test.

6. Neither test necessarily reflects minor changes or faults in production routine. Under the conditions of our experiment the methylene-blue test was not, in cold weather, a satisfactory indicator of the numbers of organisms as distinct from ‘activity’.

The results of regular determinations of the freezing-point and solids-not-fat content of the milk of three Shorthorn cows over a period of more than six months are reported.

The known constancy of the freezing-point depression was confirmed, the Δ values deviating generally by less than 2% and, in the most extreme case, by no more than 3·5% from the mean of 0·546 ± 0·002° C. No evidence was found of any influence of the state of lactation on the freezing-point depression, but a slight but definite decrease persisting for some weeks occurred at the time of year at which ample supplies of spring pasture became available to the animals.

Scott Blair & Coppen(I) have described a test for the consistency of firm cheese curd during the process of scalding and at the pitching point. This test gives the cheese maker an objective physical measure of a property which he is used to assessing subjectively by handling the curd, and should ensure a more constant condition in the curd from vat to vat and from day to day.

Trials with the Scott Blair apparatus for measuring hardness of butter by compression of a cylindrical sample showed a lack of reproducibility due to splitting or crumbling of the sample. Investigation of alternative methods led to the development of an apparatus in which the resistance of butter to cutting by a wire is measured. The method gives results which are in general agreement with those obtained with the Scott Blair apparatus, but are much more reproducible. The effect of wire diameter and thickness of block of butter have been determined, and conditions for temperature control of the sample before and during the determination have been investigated.

It has been shown that the rate of shear of butter when cut by a wire increases as a power of the load applied to the wire. The values of this power are high (index n = 8 to 15, average 11 at 12.5° C.) and show a high structural viscosity in the butter. There is no indication that butter exhibits a true yield value, but the (rate of shear)/(load) curve is such that a practical yield value is found. The practical yield value (denned as the minimum load required to produce a measurable rate of flow) provides a convenient measure of the hardness of butter. The viscosity of butter decreases rapidly as rate of shear is increased, but the rate of decrease varies from one sample to another. Measurements of spreading capacity should be made at rates of shear comparable with those which occur when butter is spread with a knife.

The effect of temperature over the range 6–18° C. on the hardness and structural viscosity of a number of butter samples has been investigated. The effect of reworking has also been studied.

An investigation of the effect of type of pasteurizer, rate of cooling after pasteurization, temperature during holding and during churning, temperature of wash water and amount of working showed that of these factors the only one which had any marked and consistent effect on the hardness of the butter was the rate of cooling of cream after pasteurization, rapidly cooled cream yielding harder butter. The use of low temperature wash water tended to reduce the hardness of the butter but the effect was small. The other factors had no consistent effect on the hardness of the butter.