Six Romney Marsh ewes exposed daily in a hot-room to temperatures averaging 105° F. dry bulb and 87° F. wet bulb for 2 months prior to the start of the breeding season all experienced oestrus and, as a group, at the same time of year as non-heated controls.

However, when maintained under daily hot-room treatment throughout the pregnancy period only one ewe lambed, suggesting an adverse effect of high temperature on gestation.

In a further experiment to confirm this, eight control ewes all lambed, average birth weight of lambs being 9 lb. 5 oz. Of six experimental ewes exposed to temperatures of 107° F. (dry bulb) and 92° F. (wet bulb) for 7 hr. daily during the last third of pregnancy, one failed to lamb and the lambs averaged 7 lb. 15 oz. A further six experimental ewes exposed to similar room conditions for the last two-thirds of pregnancy produced still smaller lambs, averaging 6 lb. 11 oz. at birth, and three ewes failed to lamb.

The yield of lamb per ewe was 9 lb. 5 oz. for controls, 7 lb. 13 oz. and 4 lb. 1 oz. for ewes exposed to heat during the final third and two-thirds of pregnancy respectively and, in the previous year's experiment, 1 lb. 2 oz. for those exposed throughout the pre-mating, mating and post-mating period.

It is concluded that although high temperature is apparently without effect on the incidence of oestrus in sheep, it is inimical to satisfactory gestation.

1. The availability of the calcium in three common herbs, viz. narrow-leaved plantain, chicory and burnet, has been investigated using the rat as the experimental animal.

2. Parallel methods used for the determination of calcium balance involved (a) the analysis of feed, faeces and urine, and (b) carcass analysis.

3. The availability of the calcium, while high in all three species, was in the order plantain, chicory and burnet. All differences between means were significant at P = 0·05.

4. There was shown to be some evidence of inverse relationships between fibre content and calcium availability, and between oxalic acid content and calcium availability.

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.

1. A study was made of the effect of underfeeding on the genital functions in the bull. Regular weekly collections of semen were made during (1) a 5-week pre-experimental period of normal feeding, (2) a 23-week experimental period of under-feeding, and (3) a 25-week post-experimental period of recovery.

2. Although the food intake was reduced to such an extent that the bull began to lose weight at a rate of 6·5 kg. (1 stone) per week, the volume and density of semen and the motility and morphology of the spermatozoa were not significantly changed.

3. In contrast to the testes, the secretory function of the male accessory glands was markedly affected by under-feeding. The concentration of fructose and citric acid in semen decreased to about 30 and 60% respectively of the original levels. During the recovery period the values for fructose and citric acid gradually returned to normal.

1. A semi-lethal gene combination has been found in hexaploid species hybrids involving some strains of Triticum macha, but not in comparable hybrids involving other strains of T. macha. The production of these semi-lethal hybrids can be explained by the interaction of two genes designated as ma and mb.

2. The gene ma is carried in some strains of T. macha. The gene mb is carried in the third chromosome set of all other hexaploid species of Triticum, in Aegilops squarrosa and in Aeg. cylindrica.

3. The semi-lethal gene combination has been found between species which would otherwise produce fertile hybrids and between species which would otherwise produce sterile hybrids. The semilethal gene combination occurs between species which do not overlap geographically.

4. The distribution of the genes ma and mb shows that the gene ma originated in T. macha and that the gene mb originated in Aeg. squarrosa and was introduced from there, during the course of evolution, into the hexaploid species of Triticum (probably excluding T. macha) and into Aeg. cylindrica.

5. Meiosis in semi-lethal plants was comparable to meiosis in normal plants. But the semi-lethal plants showed a reduction in fertility, probably as a result of their poor vegetative growth.

6. The chromosomes of T. macha and T. vavilovi have been no more structurally differentiated than the chromosomes of the other hexaploid species of Triticum.

7. The present study has confirmed that the third chromosome set of the genus Triticum has been phylogenetically derived from Aeg. squarrosa.

1. Pregnancy and lactation had no effect on the digestibility of the dry matter and nitrogen-containing constituents of the ration of Cheviot ewes fed at a constant level.

2. The water consumption of the pregnant ewe was almost doubled during gestation.

3. The digestibility coefficients of dry matter and nitrogen in both pregnant and barren ewes fell considerably from November until the beginning of the following April.

4. The average nitrogen content of a normal fullterm Cheviot foetus was approximately 99 g.

In experiments on peas, beans, carrots, kale, beetroot and spinach appropriate dressings of fertilizers placed in one band 3 in. below the soil surface and 2 in. to the side of the seed did not damage germination. Peas and beans are likely to be injured when even small dressings of soluble fertilizers are drilled in contact with or below the seed.

In sixteen experiments on peas and nineteen experiments on beans in 1949–51 broadcast fertilizer gave small increases in yield of beans and peas in dry years and larger increases in wet years. In about one-quarter of all the experiments fertilizer broadcast early and either ploughed or cultivated deeply into the soils gave significantly higher yields than late dressings worked into the seed-beds. In roughly one-third of all the experiments on each crop there were significant increases in yield from placing as compared with broadcasting fertilizer. The average extra yields produced by placing fertilizer were 1·8 cwt. per acre of threshed peas, 9·3 cwt. per acre of green peas, 1·0 cwt. per acre of winter beans and 1·3 cwt. per acre of spring beans. For spring-sown crops extra yields from placement were greater than the increases from broadcasting fertilizer. There was little advantage from splitting the fertilizer dressing, broadcasting half and placing the remainder beside the seed.

In most experiments on peas and beans, yields given by a single dressing of placed fertilizer were equal to, or greater than, the yields given by double dressings of broadcast fertilizer. When placed in the correct position quite small quantities of fertilizer are sufficient for maximum yields of such crops. The use of suitable drills should be profitable to farmers growing appreciable acreages of peas, beans and rapidly maturing horticultural crops. Where special placement drills are not available, fertilizers for peas and beans should be broadcast before cultivating to prepare the seed-bed and, when possible, the dressings should be ploughed-in. There was no advantage from placing fertilizer at the side of the seed for carrots, kale or beet. Placed fertilizer gave a higher yield of spinach than broadcast fertilizer.

Placing fertilizer at the side and below the level of the seed is likely to give better yields than broadcast fertilizer for crops having short growing seasons or poorly developed roots and when broadcast nutrients are immobilized in the surface soil by drought.

Phosphate-potash fertilizer was drilled in bands 20 in. apart and 3 in. below the soil surface and compared with similar dressings broadcast on the surface for established crops of sainfoin. On unmanured plots yields were not reduced by cutting grooves for the fertilizer bands. Broadcasting fertilizer on the surface produced consistently more sainfoin hay than dressings placed in bands. In similar experiments on permanent grass broadcast fertilizer also gave consistently more hay than bands of fertilizer placed 10 in.apart. Intheabsence of fertilizer small decreases in yields of grass were caused by cutting grooves. The advantages of an equal supply of nutrients to all the plants in an established sward, obtained by broadcasting fertilizers, outweighs any disadvantage from confining the application to the soil surface.

Two experiments on lucerne in 1950–51 compared broadcast dressings of phosphate-potash fertilizer harrowed into the seed-bed with the same quantities of fertilizer placed in one band 2 in. to the side of the seed. Side-band placement did not give better early growth than broadcasting. Broadcast fertilizer gave higher yields of hay than placed fertilizer at one centre in the first year. There were no significant differences at either centre between yields of hay given by broadcast and placed fertilizer in the second year. When the dressings were divided, half being applied at sowing-time and the remainder in the spring of the following year, slightly lower yields were obtained than from dressings applied wholly at sowing.

A further experiment on lucerne was laid down in spring 1952. Superphosphate, muriate of potash and a mixture of the two fertilizers were compared both when broadcast and ploughed in and when broadcast on the seed-bed. All the dressings of broadcast fertilizer were tested in the presence and absence of a ‘starter-dose’ of superphosphate drilled directly beneath the seed. The ‘starter-dose’ gave much better early growth and higher yields of lucerne than any of the dressings of broadcast phosphate and potash. Broadcast fertilizer ploughed in tended to give higher yields at the first cutting than seedbed dressings. At the second cutting there was little difference between yields given by ploughed-in dressings and dressings broadcast on the seed-bed.

There is no case for introducing special equipment to place fertilizer in bands below the surface of established swards. For establishing lucerne and other ley crops, where fertilizers may be applied at or before sowing, there are no advantages from using special drills to place the full dressing of fertilizer at a safe distance to the side of the seed. Where combine-drills are used for sowing herbage crops they should be modified to place a small quantity of superphosphate directly beneath the seed and the remainder of the fertilizer should be broadcast before sowing.

1. A report is given of an experiment to investigate the extent of genotype-environment interaction in the growth rate and reproductive phenomena of certain strains of mice when kept in two food and two temperature environments. Evidence of interaction was found in both characters.

2. The results are considered to be of sufficient interest to justify further work along these lines.

This might either take the form of extensive studies involving many strains and environments chosen more or less at random, or in more limited investigations where the genotypes and environments are especially chosen because of marked differences.

1. Earlier work on the digestibility of Calluna vulgaris has been briefly reviewed.

2. Determination of the digestibility of heather has been made by two methods, viz. (a) the conventional procedure involving the use of metabolism crates and (b) the lignin-ratio technique applied to tethered sheep.

3. A diet consisting of heather alone, and fed in metabolism crates, proved unsatisfactory as a result of low feed intake. Agreement between duplicate sheep in respect of digestive capacity was also poor.

4. Satisfactory feed intakes were attained when heather was admixed at levels of 40 and 70% with hay. At both levels the digestibility of the organic matter was approximately the same, and agreement between sheep was good except for crude protein.

5. The lignin-ratio technique applied to tethered sheep gave digestibility coefficients for organic matter which were consistent with those obtained by the conventional method; the values for crude protein were somewhat higher. While the organic matter of 10-year-old heather was digested to about the same extent as that of 4-year-old heather, its crude protein digestibility was rather less.

6. The advantages and disadvantages of both methods have been discussed; it has been concluded that the lignin-ratio technique is likely to play a useful part in future work of this kind.

7. These preliminary results suggest that heather has a higher nutritive value than earlier work would indicate, and that even the winter foliage may compare favourably with hay of moderate to poor quality.

Soil was maintained in a moist condition with as complete aeration as possible, for periods up to 89 weeks, either alone or after the addition of straw, ground-up mustard plants, ground-up tare plants, or ammonium sulphate. The nitrogen which existed as nitrate, ammonia, or other materials soluble in cold water, as compounds only soluble in hot water, or as substances only soluble in dilute HCl, was determined at intervals during this period. In general, little change took place after 11 weeks apart from a very slow and very slight increase in the nitrate produced, except after the addition of straw. Ammonia was reduced to a trace in all cases. The whole of the nitrogen soluble in cold water became converted into nitrate or ammonia in less than 11 weeks, except in the case of the admixture with straw. With straw there was far less accumulation of nitrate than when no addition was made, and this prevention of the formation of nitrate continued to the end of the experiment (89 weeks). The less soluble nitrogenous material (i.e. that only soluble in hot water or in HCl) was hardly affected by the long incubation.

The added nitrogen was entirely recovered after the end of the experiment, except where ammonium sulphate was used. In this case there was an apparent disappearance of 30% of the added nitrogen.

The inverse relationship described in an earlier publication between phosphate response and the degree of base saturation has been confirmed with three further groups of field experiments. As an alternative to the degree of base saturation soil pH may be employed.

The discrepancies sometimes found with the more acid base-unsaturated soils, between actual phosphate responses and those expected from the degree of base saturation were found to be related to the control yields. In general, the higher the control yield on a distinctly acid soil the more the percentage response to phosphate fell short of that expected, and vice versa. By forming multiple regressions of percentage phosphate response on both control yield and the percentage saturation of the B.E.C. a more accurate assessment of phosphate response is possible than by using the simple regression of response on the percentage saturation of the B.E.C. A measurable soil characteristic that could be used in the multiple regressions instead of the control yield was not found.

Very significant and inverse relationships were established between percentage phosphate response and the amount of water-soluble or citric acidsoluble silica. These silica contents were also found to be significantly and directly related to the percentage saturation of the B.E.C. It appears that measurements of pH, silica and base saturation function similarly in classifying the soils, distinguishing between the almost neutral soils retaining phosphate in an available form associated with exchangeable bases, acid soils with relatively unavailable phosphate associated with iron and aluminium compounds, and soils intermediate between these.

1. It is possible for a breed of cattle to persist and to expand slowly, despite the existence of a genetic defect which prevents 50% of the calves born being used for breeding. Moreover, it is possible to exert a certain amount of selection in such a breed. The Dexter breed provides an example.

2. Before 1924, about 64% of entrants to the breed were from inspected animals. Between 1924 and 1939 the breed contracted. From 1940 to 1947 the breed expanded.

3. During the period of decline almost every Dexter-type female born was registered and raised. The wastage rate and age distribution of the cows are similar in Dexters to those of other breeds. There would appear to have been comparatively little breeding from Kerry types. The average registered reproductive rate of Dexter-type females was about 0·8.

4. While it was not possible to examine the breed structure in the period of expansion, this was probably accomplished by lengthening the average productive life of the female, and possibly also by breeding from Kerry types.

5. The possibility of exercising selection in Dexters is shown to exist. Only about 13% of the females registered are used for producing registered bulls. Of the total bull crop, only about 7% are used to produce registered females, but the bulls selected have different numbers of offspring. The use of bulls selected after progeny testing is hardly feasible in Dexters. The increased numbers of females necessary in order to produce an adequate number of heifers, renders this technique almost impossible.

6. There has been little inbreeding in Dexters. This is possibly due to deliberate policy, as some of the breeders associate inbreeding with the production of monstrous calves.

7. It would, therefore, appear that the damaging effect of a lethal in a breed could be overemphasized.

1. An EEL mains-operated colorimeter has been calibrated to obtain rapid estimates of the concentration of spermatozoa in bull semen.

2. A general linear calibration relationship has been calculated giving h, the estimated concentration of spermatozoa per ml. of the original semen, as

where d is the dilution factor and Pd is the absorptiometer reading.

3. Under the circumstances of the experiments described, the accuracy of estimates from the above relation was about 1%, and it is considered that the instrument may be effectively used in semen determinations for artificial insemination and in most cases where a rapid determination is required.

4. Attention is drawn to the desirability of using standards and occasional check calibrations, and to the possibility that in routine use results may be slightly less accurate than those given above, which were obtained with laboratory determinations.

1. The effect on cow health of galactopoietic stimulation with thyroactive materials was determined from a statistical study of the results of a large field experiment involving 2000 cows over a 3-year period.

2. The same experimental procedure was followed on thirty-seven farms scattered over England, Scotland and Wales. This procedure was planned to ensure that half the cows in each herd would receive a course of treatment with iodinated casein or thyroxine, and that the other half would constitute a suitable set of controls. Cows that remained in the herds received second and third treatments in successive lactations.

3. The galactopoietic stimulation was started at a fixed interval after calving, irrespective of the season of the year.

4. The use of the thyroactive materials in successive lactations did not have any serious adverse effects on the health of cows. The effect on productivity was less than had been expected, since the increase in milk yield resulting during the period of hormonal treatment was often largely or completely negatived by a shortening of the lactation period.

5. The incidence of disease was somewhat greater in the treated than the control group, the principal contribution to this difference being from the diseases described as digestive disorders. There were some other differences of lesser significance.

6. The rate of disposal of treated and control groups was almost identical.

7. There were no adverse effects on the reproductive life of treated cows; factors studied were the efficiency of coitus, interval between parturitions, length of gestation and incidence of abnormalities at parturition.