1. A small-scale plot experiment which had been carried out from 1947 to 1949 (Holmes, 1951) to study the effect of massive dressings of nitrogen, with and without phosphate and potash, on the yield of a ryegrass dominant sward was continued in 1950–2. A 4 × 4 Graeco-Latin square was used.

The nitrogen treatments applied each year were:

(1) no nitrogenous fertilizer, (2) 260 lb., (3) 520 lb. and (4) 416 lb. (312 lb. in 1951) nitrogen per acre per annum applied in four or five equal dressings, one for each cut. Treatments 1, 2 and 3 were cut each time they reached the long leafy stage (8–11 in. in height), treatment 4 was cut when 13–16 in. in height.

The mineral treatments were (A) no mineral fertilizer, (B) 336–538 lb. K2O per acre per annum depending on nitrogen treatment, (C) 120–180 lb. P2O5 per acre per annum, (D) treatments B and C combined. Mineral applications were applied in four or five dressings each year, one for each cut.

2. Applications of phosphate did not affect the yield or protein content of the herbage, but yields were severely restricted in the absence of potash. Where potash was applied the yields under each nitrogen treatment were maintained or increased over the 6-year period. Average yields of dry matter for the 6-year period when potash was present were 4760, 8050, 9620 and 9320 lb. per acre per annum for treatments 1, 2, 3 and 4. Without potash the corresponding average yields were 3980, 5610, 5190 and 5100 lb. Average crude protein yields with potash were 710, 1410, 1990 and 1640 lb. per acre per annum and without potash 550, 1090, 1190 and 1020 lb.

3. The presence of potash resulted in earlier growth in each season through the maintenance of the earlier vigorous grasses in the sward. Although the growth curve was variable with treatment 1, treatments 2, 3 and 4 gave nearly uniform distribution of herbage production over the season.

4. The weighted mean contents of crude protein for each year ranged from 13·9% for treatment 1 to 20·6% for treatment 3 when potash was given and from 12·9% for treatment 1 to 23·6% for treatment 3 when potash was absent. There was a gradual increase in protein content at the later cuts in each season, but the range was less where nitrogen was applied.

5. The efficiency of utilization of fertilizer nitrogen was calculated. When the yield was compared with that of a no-clover sward the average response was 15·6, 10·8 and 11·8 lb. dry matter per lb. of nitrogen applied for treatments 2, 3 and 4 respectively. In terms of crude protein the percentage recovery was 53, 44 and 42 respectively. When the yields were compared with those of the clovery swards the nitrogen recovery figures were reduced by about one-third.

6. The botanical composition of the plots was determined by the nitrogen and potash treatments. Where both were adequate a vigorous sward of ryegrass and timothy was maintained. Where nitrogen was absent but potash present a clovery sward developed. In the absence of potash with or without nitrogen the better grasses declined and were replaced by poor grasses.

7. Provided potash was applied there were no marked changes in the soil analysis.

8. The results are discussed with particular reference to the maintenance of high grass yields and the relative roles of clover and fertilizer nitrogen.

Milk records and records of farm and herd management collected over a 2-year period have been used to study the effects of seasonal changes in climate, feeding and management in each of four Dairy Shorthorn herds.

Differences in climatic conditions and management between the four farms appeared to be reflected in mean lactation yields, herd D having a slightly higher, and herd C a considerably lower average than the other two herds.

In each herd, mean yields in each week were corrected for the effects of potential productivity and mean stage of lactation of the cows to give a weekly value designated the yield index. Variations in this quantity were used as a measure of the effects of seasonal changes in climate, feeding and management upon milk yields.

It is known that acidic red lateritic soils are usually deficient in available phosphorus, and whenever any soluble phosphates are added to such soils they become fixed and non-available to plants. It is believed that added phosphates make insoluble compounds of ferric phosphates with iron salts in the ferric state. Since ferrous salts are more soluble than the ferric salts, it suggests itself that if in the soil we can keep the iron in the ferrous state or can effect the conversion of ferric salts into ferrous salts it may be possible to reduce the formation of insoluble iron salts with phosphorus and thus increase the amount of available phosphorus by reducing phosphate fixation. With this object in view red latoritic soils from Dacca Farm area were kept under water-logged condition and the effect upon the conversion of Fe3+ into Fe2+ state and the change of readily soluble phosphorus were studied from time to time.

Data collected during 336 hr. of observation with ten Zebu cattle were examined to assess the extent of variation between these animals and the extent to which these animals conform to the general herd behaviour. A further use was made of the data to discuss the effects of individual animal behaviour on the numbers of animals it is necessary to observe.

Records of plant development in some twenty-five multifactorial experiments were collected with the object of analysing the effects of nutrient level, density, spatial arrangement and variety on seed production in linseed. By sampling techniques estimates were made of plant density, the extent of basal branching, the number of capsules per stem, the number of seeds per capsule and the seed weight. The expected plot yields, calculated from these data, were in good agreement with the harvested yields.

In factorial trials, involving additions of nitrogen, phosphorus and potassium, only a change in the nitrogen level increased the yield of seed, and this gain was largely determined by an increase in the production of capsules and not by any alteration in either the number of seeds per capsule or the seed weight.

Over a range of density of thirty to eighty plants per square foot the number of capsules produced per plant was inversely correlated with density. When the distance between drills was maintained at 6–7 in. and the density varied by changing the seed rate then—on an area basis—both capsule production and seed yield were rarely affected since the product of plant number and capsules per plant remained relatively constant. On the other hand, if the rate of seed delivery in the drill was kept the same and the distance between the drills was the variable for density then with a narrow width of drill (4 in.) the increase in plant density more than offset the fall in capsules per plant.

Further experiments comparing drilling and crossdrilling did not wholly confirm the importance of spatial arrangement. There was, however, evidence that at densities over eighty plants per square foot, besides a further reduction in capsules per plant, the number of seeds per capsule was depressed. Varieties were characterized by differences in seed size, the number of seeds per capsule, capsules per plant and the ability to produce more capsules at high levels of nitrogen. The superiority of the yielding capacity of Royal could be ascribed to the high rate of capsule production. Such varietal differences in capsule production have not been reported previously, and since the number of capsules per plant is greatly influenced by varying density, the common practice of basing selection on spaced plants, may not give a true assessment of capsule formation at densities optimal for seed production.

1. A pilot survey was designed to provide information on the mechanical conditions and fuel consumptions of vaporizing oil tractors, on their operation in the field and on the technique required to obtain such data.

2. Two areas were chosen offering a contrast in soil and farming types. A sampling frame was prepared for each area in which the farms were grouped according to the number of tractors.

1. Using the method given in the first paper in this series, estimates of p and a have been obtained for farm crops of winter beans grown in 1950 and 1951, p being the frequency of a dominant allele, in this case for black hilum, (1 — α) the proportion of successful fertilizations in which the pollen comes from the same plant as the ovule and α the proportion in which the source of pollen may be any plant in the crop. In the 1950 crop the estimates were in the 1951 crop they were The difference in the estimates of p is not surprising in view of the fact that the two crops were grown from different stocks of beans. The difference in the estimates of α is possibly due to the 1951 crop being much the denser.

2. In both crops, as in the case previously reported, selection of high-yielding parents produced a frequency distribution of genotypes showing no influence of inbreeding. The data from the 1951 crop failed to give a satisfactory fit with expectation. Both these facts are unexplained by the simple model of a Mendelian population varying at only one locus and with all genotypes of equal fitness. They can both be explained by amending the model so that the population is considered to vary at several loci and that heterozygotes have a slight advantage.

3. Theoretically, a bulk made up of the produce of parent plants selected for high yield should contain substantially more heterozygotes than a bulk of produce of unselected parents. This was confirmed by hilum colour counts. Estimates of yield show that the greater heterozygosity is not reflected in any increase in yield. A possible explanation is offered in terms of information theory.

A comparison of methods of measuring the structural condition of cultivated surface soil was made for two important East African soil types.

The soil samples were drawn from two field experiments: (i) a tillage trial in coffee on a porous red lateritic clay soil of recent volcanic origin; (ii) a rotation trial for cotton, on a red sandy lateritic loam of granitic origin.

Of the measurements on soil cores, total porespace and field capacity (⅓ atmosphere) showed little change, while percolation rates, free-draining pore-space and a new rainfall acceptance test all reflected the observed field behaviour of the soils, and showed fairly close and highly significant correlation. Field sieving of dry clods gave highly significant differences in the lateritic clay, the stronger clods indicating the poorer soil condition. Drysieving for ½ mm. crumb was ineffective, as was wet-sieving after wetting under vacuum. Wetting by immersion gave some differences between treatments, but higher variability and no significant correlation with free-draining pore-space. Wetting by rainfall impact on dry crumbs gave the best wet-sieving tests on the clay soil. Different sieving techniques gave inconsistent results on the sandy soil. Crumb structure measurements are not efficient indications of structural conditions on these soil types, which are of wide occurrence in tropical countries.

The effect of different amounts of irrigation water on the salts in Gezira soil has been studied by comparison of different rotations in two long-term experiments at the Gezira Research Farm. The conclusion is drawn that none of the rotations studied shows any evidence of salts rising or accumulating in the profile. There is some evidence of a removal of salts from a 6 ft. profile.

The petroleum-ether extractable oil content of native oats (dry-weight basis) ranges 3·0–8·5%, and is chiefly dependent upon variety and kernel content (which is itself a varietal characteristic). That of the kernel, which comprises 64–81% of the grain by weight, is 4–11% with a spread of about 2·5% within the variety. The kernel contains in addition about 2·5% of more complex insoluble fatty material which is released on acid hydrolysis. The husk, on the other hand, contains only a few tenths of one per cent of petroleum-ether soluble oil together with about 1% of more complex material that can be released by acid hydrolysis.

Certain environments favour higher levels of oil content within all varieties whereas others favour lower levels; Scottish samples tend to be slightly higher in oil content than English samples of the same variety.

The free fatty acid content of the oil in the kernel ranges 3–10% for sound, viable grain; the value for any sample is more dependent on environment during cultivation, harvest and storage than on the variety. After the grain is milled or pulverized the free fatty acid content rises to much higher levels within a few days.

Eighty-nine Fayomi pullets were classified into three major classes High, Medium and Low according to the intensity of egg laying. Six birds in each class were slaughtered. The major body organs were dissected and weighed. The number and diameter of the visible oocytes were recorded. The dressing out percentage was obtained. The results were as follows:

1. During the first year of laying, the averagenumber of eggs laid per day was 0·50, 0·42 and 0·24 eggs for the High, Medium and Low classes respectively.

2. There were significant differences in the ovarian weight, length and weight of oviduct, these being highest in the High class.

3. The number of visible oocytes was some 200 in all classes. There were, however, differences between classes in the maturation rate of the oocytes as measured by the differences in the diameter of successive ones.

4. The weight of blood, feathers, head, wings and legs were higher in the Low than in the High; these are all early maturing organs.

5. The weights of the full alimentary canal and the empty gizzard were higher in the High than in the Low, this might be accounted for by a greater appetite and to intake of feed induced by the higher egg production.

6. There were no significant differences in the weight of the circulatory, excretory and respiratory organs which are needed for the physiological welfare of the birds.

7. The dressing out percentage was higher in the Low and Medium than in the High. This may be due to the greater drainage of nutrients required for high egg production.

1. Details are given of the construction of one open-circuit and two closed-circuit respiration chambers suitable for the determination of the 24 hr. exchange of energy of calves or of other animals weighing up to 75 kg.

2. Gas analysis apparatus and the general technique employed in experiments with the closedcircuit apparatus are described.

3. From experience gained with both types of apparatus the closed-circuit apparatus is preferred for its simplicity and ease of working.

The nitrogen content of oats depends chiefly on the nitrogen content (1·4–3·9%) of the kernel and the kernel content (64–81%) of the oats, the husk containing only 3–10% of the total nitrogen in the grain.

Varietal differences are significant but small in comparison with the overall variability: they reach 0·3% nitrogen in a few cases. Variation between random samples is largely due to soil differences, with region and harvest year responsible for smaller effects. The predominant factor governing nitrogen level in oats of all varieties probably is, as for wheat, the level of available nitrogen in the soil in late spring and early summer, just prior to heading and during development of the grain.

Within the variety there is a pronounced inverse correlation between nitrogen and oil content which is independent of grain size: the variability of the oil content within the variety is, however, smaller than the corresponding variability of the nitrogen content. At some localities environmental factors of soil and season, particularly the former, inhibit the filling out of the grains which then ripen prematurely to give small oats with lean kernels of high nitrogen content, and favour within the variety a negative correlation between grain size and nitrogen which otherwise might not be apparent.

1. A survey and. statistical analysis of the records of litters born in the N.I.R.D. herd of Large White pigs over a period of 16 years are presented.

2. The mean length of gestation was 114 days for both gilts and sows.

3. The mean numbers of pigs born alive and born dead per litter from gilts, 10·0 and 0·2 respectively, were both significantly smaller than the corresponding figures for sows, 11·8 and O·8. No seasonal differences were found.

4. The mean total losses of pigs from birth to weaning at 8 weeks were 29·5% of pigs born alive. The losses in litters from gilts, 23·0%, were significantly smaller than in litters from sows, 31·0%. The losses during the winter months both for gilts, 32·5%, and for sows, 35·9%, were significantly higher than during the summer months, 19·4% and 26·7% for gilts and sows respectively.

5. Over 50% of the total losses were due to crushing by the dam, 74·1% of the losses from this cause occurring during the first 48 hr. after birth.

6. The mean number of pigs weaned per litter was 8·0. The difference between the number weaned per litter from gilts, 7·7, and per litter from number of pigs was weaned per litter from sows during the summer months, 8·7, than during the winter months, 7·4.

7. There was no significant difference between the number of male and of female pigs weaned.

8. The mean weight at weaning was 29·9 lb., male pigs, 30·3 lb., being significantly heavier than females, 29·51b. Pigs in litters from gilts, 27·81b., were significantly lighter at weaning than those from sows, 30·0 lb., and for both gilts and sows, pigs reared during the summer months, 29·7 and 31·8 lb. respectively, were significantly heavier than those reared during the winter months, 25·9 and 28·2 lb. respectively.

An experiment has been performed on the effect of sulphanilamide on the calcium and phosphorus metabolism of laying hens.

The results showed a decrease in calcium retention and thinner shelled eggs, when sulphanilamide was fed.

When the drug was withdrawn the birds took some time to reach normal balance values again, but they immediately produced normally shelled eggs.

The results of this experiment, along with a previous experiment, have been considered from other points of view in an attempt to find an explanation of some slightly divergent results. Relationships between calcium retained and calcium in shell and between calcium balance and phosphorus balance have been found and the values for changes in calcium bound to phosphorus and residual calcium in bone have been calculated. These considerations have helped to clear up the discrepancies, and it would appear that sulphanilamide effects may be influenced by season, and by calcium and phosphorus intake.

The investigation shows that when ammonium sulphate or oil cake was applied to cropped rice soils 4 weeks after transplantation, a considerable amount of the added nitrogen was lost as gas. This loss, however, was less than the loss that took place when the crop was absent. Placement of ammonium sulphate 3 in. below the soil surface reduced the loss of nitrogen, but did not significantly increase the crop yield. Gases evolved from cropped rice soils, whether unmanured or treated with ammonium sulphate, were free from hydrogen and contained practically no methane, while those formed in the uncropped soil under similar treatments contained large volumes of these two gases.

1. Two 4-month-old Ayrshire calves were subjected in a climatic room for periods of 2½–4½ hr. to an atmosphere having a temperature of 35° C. and an absolute humidity of 34 mg./l.

2. This treatment resulted in an increase in respiration rate, a decrease in carbon dioxide tension and carbon dioxide combining capacity of the venous plasma, an increase in the lactic acid concentration of the venous blood and an increase in the pH of the urine. The pH of the venous plasma showed only a slight tendency to increase.

3. It is concluded that thermal panting under the conditions described caused a carbon dioxide deficit which was just compensated for by the excretion of alkali by the kidneys, and that this compensation was not substantially influenced by the production of lactic acid resulting from an increased activity of the respiratory muscles.

1. Egg-shells from six inbred lines of Brown Leghorn fowls were examined for porosity and thickness in March and in July.

2. For both characters studied the variation between-line means was found to be significant.

3. The line means for thickness were with a single exception lower in July.

4. Porosity coefficients increased from March to July.

5. No significant relationship between shell thickness and porosity was found in either season. Line differences in porosity values are therefore attributable to variations in other properties of the shell.

1. During the course of investigations on the influence of High- and Low-nutritional planes on the growth, reproduction and production of heifers, sexual activity was studied by recording oestrus data. A total of 239 observations were recorded for fourteen maiden heifers for each nutritional plane; 161 for the High-plane individuals and 78 for those on the Low plane. The investigation included four breeds, viz. Beef Shorthorn, Afrikaner, Friesian and Jersey.

2. The average length of the dioestrous cycle was 20·16 days for the High-plane animals, and 20·83 days for their Low-plane counterparts, the difference of 0·67 days not being statistically significant. Breed differences were not very marked, but a tendency was revealed for the Friesians of both planes to have slightly longer cycles on an average than any other breed studied.

3. The modal length of the cycle for both groups was found to be 19 days, with 95·6% of the cycles falling within the normal range of 17 to 23 days. Cycles exceeding 33 days in length were, however, excluded from these calculations.

4. A tendency was revealed for the initial postpubertal cycles to be longer on an average than what is usually considered the normal length. Although the High-plane heifers settled down to a regular rhythm sooner, observations showed that differences existing between individual animals is probably of greater significance in this regard than any other factor.

5. Whereas the majority of the High-plane heifers reached puberty during winter, 85·7% of the Lowplane heifers came on heat for the first time in summer. It is suggested that with the approach of favourable nutritional conditions, animals in a low condition first restore depleted body tissues before the sexual cycle returns to normal activity.

6. A slight tendency was noticed for cycle length to vary with the season in the case of the High-plane animals, longer cycles being recorded in summer than in winter. On the Low plane, however, the heifers concerned invariably experienced an anoestrous condition during winter, lasting anything up to 218 days. Only after they regained the losses in live weight, was sexual activity restored as previously pointed out.

7. Sexual activity was shown to be greatest in late summer with little variation over the remainder of the year under normal conditions of nutrition and management, while in the Low-plane individuals it fluctuated from complete inactivity in midwinter to a peak in summer.

8. Post-partum oestrus was considerably delayed by lactation in the beef animals. The High plane heifers came on heat only after weaning their calves while the Low-plane individuals required nearly a year in addition to regain depleted body reserves before sexual activity was restored. The Low-plane dairy heifers showed a longer post-partum anoestrous period also, the difference between the two groups being 20·77 days.

9. The results for the number of services required per conception demonstrated that the Low-nutritional plane caused no detrimental influence on this factor. In fact, the difference existing between the two groups studied was in favour of the Low plane animals. This is in agreement with Asdell's (1952) findings. It was shown that season had no effect on the results obtained.

Semen samples were collected from twelve fattailed rams of two breeds (nine Ossimi and three Rahmani), by the use of an artificial vagina. They were kept under natural conditions at Cairo, Egypt (30° N.). Three collections were made each month throughout one year (1951–2).