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.

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.

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.

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.

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.

The histochemical localization of acid and alkaline glycerophosphatase (phosphomonoesterase) has been determined throughout the reproductive tract in the bull. Sections were incubated in a buffer substrate containing sodium β-glycerophosphate at pH 4·5 and pH 9·4. Duplicate sections were incubated for progressive lengths of time ranging from ½ hr. (alkaline phosphatase) to a maximum of 48 hr. (acid phosphatase).

Evidence of the presence of both enzymes has been obtained in the tissues which compose the reproductive tract. In the case of acid phosphatase the reaction was predominant in the nuclei of the lining epithelial cells. In addition, a positive cellular reaction was found in the distal portions of the epithelium lining the epididymis, the ampulla of the vas deferens and the seminal vesicles. The reaction obtained in the testis appeared to vary with the stage of activity of the tubule.

In the case of alkaline phosphatase the reaction was predominantly shown by the basement membrane and the capillaries throughout the tissues with a cellular reaction in the distal portions of the cells lining the epididymis, the ampulla of the vas deferens and the seminal vesicles. In the seminal vesicles the type ‘A’ cells reacted strongly while the periphery of the osmic staining vacuoles of the type ‘B’ cells also gave a positive reaction. The only activity present in the prostate was in the capillary endothelium. The spermatogenic epithelium showed a positive reaction, but no reaction was given by the interstitial cells.

The investigations that have been in progress at the Grassland Research Station, Stratford-on-Avon, on the management of grassland for the production of winter pasturage are discussed as four experiments, E 62, E117, E 86 and E158.

Exp. E 62 was concerned solely with herbage production, while the remaining three have taken into account the performance of the beef animal under such pasture treatment.

The maintenance of condition in the animal has proved possible over a number of winter seasons from 1948 to 1953, sufficiently so to warrant investigation of the means of providing as abundant pasturage as possible at this time of year from latesummer and autumn rested swards. The importance of integrating a system of winter utilization with summer production has become evident in the course of the work, and the necessity of upkeeping sward condition, more especially the grass-legume balance, has been realized. The use of alternate drills of grass and lucerne shows considerable promise in this respect. Intensive utilization and production has taken place from such seedings at all seasons without serious sward deterioration.

The development of a grazing system for outwintering cattle destined to be fattened on summer pastures would provide a means whereby such cattle would be fed with as little attention and labour demand as is consistent with good stock management. With the need for cheapening of costs in beef production methods in Britain attention might well be paid to the methods outlined in the light of the experimental data presented.

The ages of the Clun ewes considered in the survey were ranged from between 1 and 4 years in practicbreeding ally every case. They had thus not attained their maximum fertility which probably occurs at the age of from 4 to 6 years. A consideration of the fertility in the breeding flocks does not provide an estimate of the maximum for this breed, which can only be obtained from older draft ewes which are used in crossbreeding flocks with the object of fat lamb production.

Barrenness is relatively unimportant in ewes, but affects approximately one-third of all breeding ewe lambs each year. Abortion was insignificant amongst ewes but was more common amongst ewe lambs.

1. Trials over 2 years involving 120 Half bred ewes were conducted in outdoor paddocks with controlled feeding. A study was made of the effect of varying the level of feeding during pregnancy on production of ketonaemia and pregnancy toxaemia.

2. Blood ketone levels were low and pregnancy toxaemia absent in ewes gaining weight during the latter part of gestation, but ewes failing to gain weight over the same period were subject to ketonaemia and pregnancy toxaemia. A reduction in the ration of fat ewes for a 3-week period, imposed more than 5 weeks before lambing, had no detrimental effect.

3. A significant correlation was found between loss in weight and highest ketone figure in the highthroughout and the high-checked groups in 1952 and in the high-checked-high group in 1953.

4. High ketonaemia was not always indicative of pregnancy toxaemia, since of the twenty-nine ewes which had, on one or more occasions, over 20 mg. β-hydroxybutyric acid per 100 ml. blood, seven showed signs of pregnancy toxaemia and twentytwo did not.

5. In the cases reported, the time of appearance of the first symptoms of pregnancy toxaemia was around 14 days from the estimated lambing date, and affected ewes tended to lamb before term.

6. On a comparatively low level of nutrition, only one case of pregnancy toxaemia occurred, though some animals had marked ketosis. In well conditioned ewes reduced to a similar level during the critical period, there was a high incidence of pregnancy toxaemia, and in most of these cases a high degree of ketosis.

It is suggested that part of the increased permeability of soil recently ploughed out from grass could be due to water conduction through the severed roots. Microtome sectioning of a root of Lolium perenne showed a continuous metaxylem element of about 30μ diameter, with only minor restrictions, forming a natural capillary tube. Further, being at the centre of the stele, the metaxylem should persist for some time after the grass has been killed. Hydraulic diameters calculated from laboratory experiments on the rates of water conduction by severed L. perenne roots were in reasonable agreement with the diameter of the metaxylem measured by direct sectioning.

Similar experiments on Phleum pratense were more difficult to interpret due to the complexity of the metaxylem, the number of elements not being constant along the root. The rate of water conduction by roots of Dactylis glomeratus was found to be small compared with the other grasses, for although having the largest number of elements they are the smallest in size of any grass examined.

The permeability of a severed Lolium perenne root system, calculated on the basis of the surface density of roots found on 4-year-old plots, indicated that the root system should significantly increase the unsaturated permeability of soil at low suctions. To obtain maximum benefit the ‘capillary tubes’ should be severed immediately under the turf and not at ploughing depth. Accordingly, two plots were laid out on old grassland to compare normal autumn ploughing with shallow rototilling on the subsequent germination and growth of spring wheat. In spite of repeated rototilling, however, it proved impossible to kill the grass in the wet winter conditions and the wheat was smothered. A comparison of the suctions developed at 5 cm. in the two plots showed that the unsaturated permeability of the rototilled plot was higher.

Although the laboratory results are encouraging there is as yet no conclusive evidence that the natural water supply and drainage system formed by the severed roots is important under field conditions.

Fourteen pairs of monozygous twin cows of mixed ages were used to determine the effect of underfeeding from the 3rd to the 8th week inclusive after calving on milk and butterfat production and on the composition of the milk.

Those cows which were well fed over the 6-week period produced more milk and a larger weight of butterfat than their sisters which had been poorly fed. The milk from the well-fed cows had a lower percentage of butterfat, but higher percentages of solids-not-fat and total protein, than the milk from the poorly fed cows.

The complete lactation averages failed to show statistical significant differences in all characteristics except in the case of solids-not-fat percentage. The mean difference between the two groups for solidsnot-fat was found to be highly significant.

In general, the results support the conclusions of other workers, that underfeeding dairy cows may depress the solids-not-fat content of the milk.

It appeared that differences between the two groups in butterfat percentage over the 6-week experimental feeding period were strongly correlated with differences in weight changes and that the small amount of variance associated with milk yield differences was not significant.

In 1939, Pinous & Waddington reported tetraploid early cleavage stages of the rabbit after colchicine treatment of fertilized eggs in vitro. Chang (1944) inseminated rabbit does with sperm suspended in 1/1000 colchicine in 0·9% NaCl and noted a few abnormal young in the resulting litters. No chromosome counts were made, but Chang considered the possibility that colchicine had entered the egg and caused polyploidy. Using the same technique as Chang, Swedish workers have claimed the production of two adult triploid rabbits and one adult triploid pig (Häggqvist & Bane, 1950a, b, c, 1951; Melander, 1950, 1951). This Swedish work has been criticized (Beatty, 1951; Beatty & Fischberg, 1950; Becker, 1952–3; Hertwig, 1951; Nachtsheim, 1950; Rostand, 1951; Venge, 1953). Nevertheless, the technique is ingenious and the claim of great interest. The present note records preliminary attempts to extend the technique to cattle and to confirm the results in rabbits.