1. A method of perfusing the skin of the flanks and the backs of Ayrshire calves and embryos with indian ink is described.

2. The distribution of blood vessels in the perfused skins has been studied.

3. Three plexuses of blood vessels have been observed in the skins. The first lies below the corium; the second is at a level between that of the ‘sweat glands’ and the sebaceous glands; and the third extends from beneath the epidermis to above the second plexus and is a deep network of many fine blood vessels.

4. The presence of venae comites in the skin is discussed.

5. The ‘sweat glands’ appear to have a very poor blood supply, while the hair follicles and papillae are richly supplied.

6. Both the ‘sweat glands’ and the hair follicles are supplied with blood from the second plexus.

7. The vessels of the third plexus appear to enmesh the individual hair follicles at different levels.

8. Blood vessels supplying the skin in the back and flanks of the animals originate from the intercostal arteries and so pass through the heat generating intercostal muscles.

1. During the period May 1948 to May 1952, a study was made of the influence of seasonal fluctuations in the nutritive value of the natural pastures in the Bankenveld region of the Transvaal, on the growth, reproduction and production of cattle. The paired method of investigation was adopted, each heifer maintained on grazing alone having a related counterpart of the same age which received supplementary feeding during the winter months. The former treatment was termed ‘Low plane’, and the latter referred to as the ‘High plane’. Four breeds were included in the investigation, viz. Friesians and Jerseys, and Shorthorns and Afrikaners, thus representative of both dairy and beef types. The latter breed also represented the stock indigenous to South Africa. Initially five pairs per breed were studied, but deaths and other causes depleted the numbers to twenty-eight head after 4 years of investigation.

2. Since the investigation formed part of a series of studies which have been in progress at the University of Pretoria and Agricultural Research Institute during the past two decades, the results of which hitherto remained unpublished, a review is provided in the early chapters. To furnish some indication of the natural conditions ruling in the Bankenveld region, the agro-ecological background is discussed, particular attention being paid to physical and nutritional factors. It is shown that for at least 6 months of the year the climate tends to be subtropical, whilst the results of digestion trials on pasture samples, indicated serious nutritional depressions in the natural grazing during winter.

1. Two sample cockerels from each plane of nutrition treatment were killed and dissected at 0, 4, 10, 15 and 24 weeks of age. Details of the dissection technique are given.

2. All organs and tissues were weighed both wet and oven-dried. The total dry-matter content of the birds increased from 21% at hatching to 32% at 24 weeks.

3. The chief age changes in the proportions of the major joints of the bird consist of a marked increase in relative mass of wing, and a lesser increase in the leg joints. The early maturing head and neck joints decrease in relative mass by approximately onehalf. There are no treatment differences in the gross proportions of the birds calculated on the basis of weights of the major joints.

4. The advantages and disadvantages of the various methods of presenting quantitative growth analysis data are discussed. Reasons are given for employing several different methods in this work.

5. The amount of fat in the carcasses analysed varies considerably between individual birds. There are no consistent age or treatment effects on the fat contents of the cockerels. The interpretation of McMeekan's dissection analysis data is discussed, and reasons are advanced for conducting future experiments of similar nature on the basis of a fatfree carcass. It is argued that adipose deposits should not be considered in the same category as body organs and tissues.

Observations were made on four Suffolk lambs from birth to 14 months of age, wool and skin samples being taken periodically. The lambs were on a high nutritional plane and grew well throughout the experiment.

1. There is good agreement between estimates of growth based on body weight, calculated surface area, and expansion of tattooed squares.

2. Fibre Type Arrays were Valley or Plain.

3. Benzene tests showed considerable medullation in the fleeces of all the lambs, mainly in the posterior parts. There were practically none on the shoulder.

4. The weight of keratin produced daily per unit area of skin reached or exceeded the figure given as maximal by Galpin (1948) in only six samples, of which four were grown prior to 1 month old.

5. The follicle population completes its development early, only a few secondary follicles being added after birth. The definitive S/P ratio is 5/, which is similar to the Leicester, and lower than in the Romney breed. The follicle density, although high at birth, is lower than in the Romney or Leicester, after 9 months old. Both S/P ratio and follicle density are higher than in the Blackface breed.

6. The transitory black colour of the birth-coat of Suffolk lambs is due to pigmentation of the tips of many fibres; this may affect any type of fibre from haloes and sickles to histerotrichs. With very few exceptions all follicles cease to produce pigmented fibre at or shortly after birth of the lamb. Large amoebic melanoblasts are present in the skin.

Investigations have been carried out in this department in recent years with the object of establishing the minimum protein requirements of the bacon pig. The results were recently summarized in this Journal (Woodman & Evans, 1948). The minimum protein standards recorded in that communication are consistent with the attainment of the maximum rate of growth compatible with the net energy content of the diet. The basal foods employed consisted throughout of 2 parts of barley meal and 1 part of middlings (fine bran), together with a little lucerne meal and minerals. Briefly, it was found that such a diet, when supplemented with 7% of white-fish meal, supplied the minimum amount of digestible protein required for the quickest possible rate of growth between weaning and 90 lb. live weight, when the level of feeding was such as is shown in the feeding chart (see Table 7). It was also found unnecessary to include any protein concentrate in the diet beyond 90 lb. live weight to ensure the maximum rate of growth over this later period. The requirements were based on the results of statistically designed growth trials, and were confirmed by nitrogen-balance determinations carried out in metabolism crates. It was found that nitrogen retention was just as favourable on the basal diet supplemented with 7% of white-fish meal as when the protein level was increased by feeding higher amounts offish meal.

1. Ten local Zebu cows representative of Africanowned cattle in Central Tanganyika, maintained under good African husbandry conditions, were temperatured twice daily over a period of 134 days from 23 July to 3 December, whilst the general meteorological environment was recorded.

2. The period of observations was divided into four parts, during two of which differential planes of nutrition were maintained between two groups of animals, the first and last parts being control periods when the plane of nutrition was common to all animals.

3. The diurnal variation in rectal temperature wasapproximately 99·0–102·5° F., arange of 3·5° F., whilst the atmospheric shade temperature varied about 12° F., from 64 to 76° F. at commencement of observations, and from 71 to 83° F. at the warmest period of the observations.

4. The variation within morning rectal temperatures was greater than that within afternoon rectal temperatures.

5. The low rectal temperatures in the mornings reflected inadequate nutritional level to maintain body temperature, as they were significantly increased by a moderate supplementary ration.

6. Supplementary feeding did not affect the afternoon temperatures.

7. Daily mean rectal temperature of the cows in the morning was verysignificantly negatively correlated with atmospheric temperature.

8. Rectal temperatures of ten cows' temperatures at 2 hr. intervals from 07.00 to 21.00 hr., over a period of 7 days, was positively correlated with direct sun temperatures taken 4 hr. before rectal temperatures.

9. Rectal temperatures were positively correlated with the dew-point in the morning, but were unrelated with the lower dew-point in the afternoon.

10. It is suggested that afternoon temperaturing of experimental animals of local Zebu type under African husbandry conditions might be more informative for clinical purposes than the customary morning temperaturing, owing to the lower variation.

11. It is tentatively suggested that the thermoregulatory system of local Zebu cattle may be regarded as operating a micro-adjustment mechanism to compensate for immediate variations in micro-climate, superimposed on a macroadjustment mechanism to extend the limits of operation of the micro-adjustment in accordance with seasonal trends of the macro-climate.

12. Further data are being collected to clarify these tentative conclusions.