Study of the nutritional requirements of sugar cane on a Jamaican estate necessitated simultaneous experimentation with five manurial factors: sulphate of ammonia, superphosphate, muriate of potash, bagasse, and filter press mud. By adopting a one-third replication of a 35 factorial scheme, each factor could be tested at single and double levels for comparison with the absence of the factor.

The structure and confounding system of the design adopted have been described and the method of computing the analysis of variance has been explained. Fractional replication introduces special problems of interpretation, and this experiment illustrates how they may be resolved. Each fertilizer clearly benefited the crop, and several interactions appeared; some ambiguity of meaning is an inevitable concomitant of fractional replication, so that care was needed in order to assign effects to the right causes. The most clearly marked effects were:

(i) Without phosphate, nitrogen failed to produce any response; where phosphatic manuring was adequate the crop responded well to nitrogen.

(ii) Superphosphate and filter press mud were practically interchangeable as sources of phosphate.

(iii) Bagasse appears to act as a source of potash; the interaction of responses is not very clearly established, but little extra response to artificial potash occurred when bagasse was given.

(iv) No evidence was obtained that the double level of any fertilizer was superior to the single.

There was also a suggestion of a reduced superphosphate response in the presence of bagasse.

If a recommendation on manuring were to be based on this experiment, it would be that a maximum of 3 cwt. sulphate of ammonia per acre be used with either 4 cwt. 18% superphosphate and 1 cwt. muriate of potash per acre or 10 tons filter press mud and 20 tons bagasse per acre. In reality, of course, no attempt ought to be made to determine a general manurial policy from results of a single year of experimentation on plant cane at one place.

The experiment should be regarded rather as typical of what can be done than as a complete investigation of manurial needs.

The extent to which early environment affects wool production of Romney sheep was studied by means of measurement of skin growth, and of fibre numbers and dimensions, of lambs reared to 52 weeks on contrasting planes of nutrition.

Measurement of skin growth revealed a series of gradients which generally conformed with growth and development principles. A great degree of individuality among animals in skin growth on various regions was expressed, and it was not possible to prove that plane of nutrition caused differential skin growth among regions.

An initial low plane of nutrition had a retarding effect on fleece development and fibre growth, but it could not be decided whether there was a permanent effect on fibre numbers. It seems that this is of little practical importance, since a low plane of nutrition during the major part of the follicle development phase does not appear to impair subsequent unit area production, providing immediate nutrition is good.

Examination of fibre attributes, and quantitative fibre growth characteristics on various regions of the body, showed a series of orderly gradients. Large differences existed between the body regions for quantitative production per unit area and this suggests a widely differing nutrient supply of various skin regions.

The importance of immediate nutrition is emphasized. It appears that permanent effects of early environment on future productivity take the form of a lesser area on which wool is produced. The efficiency of the processes, apparently, is not affected.

The partition of carotenoids and vitamin A in the colostrum of nine cows and six goats and in the milk of three cows and two goats was determined using chromatographic and spectrophotometric methods. The following were the main results:

1. The content of β-carotene and vitamin A in the colostrum decreased rapidly during the first nine milkings in both the cow and the goat. The rates of decline were logarithmic. Logarithmic regressions also showed that the decreases in β-carotene were more rapid than those of vitamin A.

2. The heifers secreted more vitamin A in their colostral fat than did cows on the same ration. The vitamin A content of the colostral fat of goats was greater during the first lactation than in later lactations. There was no difference in the rates of decrease of the vitamin A content of heifer and cow colostrum, but the difference between the rates of decreases of colostral vitamin A of first and later lactation goats was significant.

3. The colostral fat of cows at pasture contained more vitamin A than that of cows on winter rations. There was no difference between the logarithmic rates of decrease in the two groups during the first nine milkings. The colostral fat of four goats receiving winter rations was richer in vitamin A than that of three cows treated similarly, and this superiority of the goat over the cow persisted throughout lactation.

4. There was no difference between the carotene content of the colostral fat of the first and later lactation cows. The yield of fat and β-carotene of the heifers was smaller than that of the cows. Cows at pasture secreted more β-carotene in their colostrum than the cows on winter rations. The presence of β-carotene was demonstrated in goat colostrum, although mature goat milk was free from any measurable quantity of carotenoids.

1. The data from a survey of beef production in West Wales has been subjected to analysis by the various regression equations deduced by Callow. The calculations have elucidated the quantitative proportions of fatty tissue, muscular tissue and bone tissue as well as the calorific values of the beef carcasses derived from animals of the various grades.

2. It is suggested that the method can be used as a basis to determine the controlled prices of fat cattle. The scale of prices thus obtained might encourage a better finish of the cattle and would tend to modify the seasonality of deliveries.

3. The process of fattening cattle alters the proportions of fatty, muscular and bone tissues in the carcass meat, but the increase in the quantity of muscular tissue is always greater than that of the fatty tissue. At all grades, the quantity of muscular tissue in the carcass is always greater than of fatty tissue.

An experiment, designed to test different ways of using straw with fertilizers, and involving a three course rotation of crops, was carried out at Rothamsted between 1933 and 1951. The methods of analysis developed for this experiment are described in the present paper and demonstrated using yields of potatoes.

Treatment effects of interest are given by the mean yields over all years and the linear regressions of yield on time. These estimates are straightforward but the evaluation of their errors is complicated by the existence of correlations due to the recurrence of treatments on the same plots. Further complications are introduced when, as frequently happens in long-term experiments, treatment effects show real variation from year to year. A method is given for estimating standard errors which include a contribution from this variation.

The various relationships between yields and the uncontrolled seasonal factors can also be examined; in the present experiment there is some indication that the effects of treatments on yields of potatoes are influenced by the dates of planting.

In other circumstances the analysis requires modifications, some of which are briefly considered.

The composition and weight of young cotton leaves at a fixed age are given for 3 years which had different rainfall before the sowing of the cotton, and for which the final yields of the cotton are also known. These yields are inversely related to the early growth and percentage composition of the crop. It is not possible to explain this, but the differences in early growth and nutrient absorption are in accord with expectation. In a year of heavy rainfall before sowing, surface soil nitrates are low, which accords with the smaller amounts of nitrogen taken up by the plants. Furthermore, there is evidence to suggest that in such a year the physical condition of the soil would be poor, which is consistent with poor growth and the low uptake of nutrients other than nitrogen.

In the Sudan Gezira the yields of irrigated cotton are positively correlated with the amount of rainfall in the 6 weeks before sowing. This is not due to increased nitrate in the top foot of soil nor is it due to increased efficiency of absorption of nutrients in years of high rainfall.

After it had become evident that vitamin B12 can be considered as a part of the so-called ‘Animal Protein Factor’, several experiments with young fattening pigs have been carried out in the Netherlands. The purpose of these experiments was to gain experience as to the value of products rich in vitamin B12 for pig feeding. In these trials 312 animals were used.

The results can be summarized as follows:

1. Substitution to a large extent of animal protein by vegetable protein in rations containing tho same total percentage of protein resulted in a retardation of growth.

2. Addition of vitamin B12 supplements to feed mixtures low in animal protein in this series of experiments generally gave better results than could be obtained without this addition. In the majority of cases, however, the results did not equal those of the groups which received rations containing the usual amount of animal protein.

3. Vitamin B12 can be considered as a component of the animal protein factor, but besides this there probably exist other factors which contribute to the special value of animal protein for young pigs.

4. In circumstances such as prevail in the Netherlands, little benefit can be derived for pig fattening from the use of products rich in vitamin B12.

1. Observations made on growing a series of crops in rotation over a range of static ground water-levels in a Fen peat soil are recorded.

2. The crops used show differences in their reaction to ground water conditions, and the seasonal incidence of rain has an overriding influence on their performance.

3. The effects of ground water-level may operate directly on the growth and development of a crop or may influence it indirectly through factors such as weed infestation, difficulties of cultivation, or the incidence of disease.

1. Chromosome pairing has been studied in twenty-two different sterile F1 hybrids involving the genera Aegilops, Agropyron and Triticum, together with their colchicine derived amphidiploids having chromosome numbers of 2n = 42, 56 and 70. Cytological evidence has been correlated with male and female fertility, while chromosome pairing in the parents has been studied in relation to their amphidiploids.

2. Some of the sterile F1 hybrids showed little or no pairing, while in others the pairing was appreciable. There was an association of the amount of pairing with the parental combinations used in the production of the hybrids in that the interspecific hybrids were characterized by a relatively high degree of pairing, particularly those with 28 chromosomes, while the intergeneric hybrids either lacked pairing or showed a low incidence.

3. In the A1 amphidiploid generation, chromosome pairing was in all cases high, and in some cases almost complete. In all cases multivalent formation in the amphidiploid was lower than bivalent formation in its undoubted F1 hybrid. Different amphidiploids showed various degrees of differential affinity. Univalent formation occurred in some amphidiploids, while bivalent formation in some was increased by a loss of chromosomes.

4. In all cases there was a reduction in chiasmata per nucleus and chiasmata per bivalent in the amphidiploid compared with its parent species. Reduction values were not directly associated with any increase in chromosome number of the amphidiploid, nor with the presence of multivalents.

5. No confirmation could be obtained of the view that multivalent formation in amphidiploids is a more generally sensitive index of chromosome homology than bivalent formation in the undoubted F1 hybrid. The absence of multivalents in an amphidiploid does not disprove the existence of structural chromosome homologies between the two parents.

1. The effects of injections of oestradiol dipropionate, testosterone propionate and progesterone in immature pullets have been studied.

2. Oestradiol dipropionate evokes hypertrophy of the oviduct, and increases in serum calcium and serum riboflavin.

3. Testosterone propionate evokes hypertrophy and reddening of the comb and wattles, it acts synergistically with oestradiol dipropionate in evoking hypertrophy of the oviduct.

4. Progesterone antagonizes the effects of oestradiol dipropionate and testosterone propionate on the growth of the oviduct.

5. Progesterone and/or testosterone propionate increase the percentage of free riboflavin in the hypertrophied magnum from 18% of the total vitamin present to 35%.

1. The partition of riboflavin into free vitamin, flavinmononucleotide and flavin-adenine-dinucleotide in the livers and magnums of laying hens fed a diet rich in riboflavin has been determined.

2. Free riboflavin in the liver amounted to 4·3% of the total vitamin, and it is concluded that this tissue does not play any part in the day-to-day metabolism of riboflavin secretion in the albumen.

3. The average amount of free riboflavin in the magnum is 45% of the total vitamin. As an egg passes through the organ, the amount decreases; this decrease is equal to the amount secreted in the albumen of the egg.

4. It is suggested that riboflavin accumulates in the blood while an egg is in the magnum, and in the magnum in the intervals between the passage of eggs, and that the riboflavin in the albumen is secreted at the same time as the albumen.

Ayrshire Cattle Herd Books for the years 1927, 1946 and 1947 were examined to study the breed structure. Extended pedigrees of a sample of registered females showed that more than half their genes had come from eight herds. Most of the genetic contribution of these herds comes through the bulls they breed.

Herds were divided into: breeders' herds (a), breeders' herds (b), multipliers' herds (i), multipliers' herds (ii), and herds registering males only. The function and numerical importance of each group is shown. The position of any one herd in the breed hierarchy is unstable. Changes in the extent of specialization of herd function between 1927 and 1946 are described.

The Ayrshire breed structure is discussed in the light of its implications on the effective size (N) of the population and on the selection of bulls for breeding.