Cytological stvidies did not show any detectable structural changes which could be related to the spermhead deformity in a series of sterile bulls described by Hancock. The deformity according to Hancock consists of a deeply stained (in iron haematoxylin) area placed askew at the apex of the spermhead.

In spermateleosis it is connected with persistence of the shallow apical groove of the nuclear membrane observed only in earlier stages of development in normal cases. There is also a formation of vacuoles in the developing spermheads in the region of the apex and of the equatorial belt. The apex of the abnormal spermhead treated with Feulgen reagent appears to be cut off askew.

Formation of vacuoles in the developing spermheads may be related to some unknown changes in the nucleic acid metabolism of the spermhead. The absence of any chromosomal aberration, whether of quantitative or structural nature, may lead to the conclusion that the changes observed are due to a gene mutation.

1. The relationship of semen age to conception rate was studied at two artificial-insemination centres and a subcentre of one of these. Data relating to 50,213 first inseminations were included in the analysis.

2. It is shown that external conditions can affect the rate of decrease of conception rate with semen age.

3. Records giving c.r.'s for each day of semen age may reveal centre differences that cannot be detected in records giving mean c.r.'s only.

4. Information may be lost if data are grouped by months rather than recorded by collections.

5. The rate of decrease should not be used for comparing centres until the various factors affecting it (e.g. breed differences) are more fully understood. Further investigations should not be limited to one centre.

1. The use of the technique of gas-partition chromatography in the investigation of the formation of volatile acids in minced grass/water slurries is discussed.

2. Slurries kept anaerobically at 17, 37 and 62° for 13 weeks have been examined, and the amounts of the different volatile acids formed have been estimated. It has been noted that butyric acid forms most readily in the slurry at 37°, while in aerated slurries at 17°, the formation of volatile fatty acids is more speedy than under anaerobic conditions.

3. Only acetic, propionic and butyric acids have been noted so far, and the highest concentrations of the acids observed in any slurry were 5, 1·25 and 4% respectively.

1. Further studies were carried out during 1950 on the effects of different ground water-levels upon the productivity and composition of Italian ryegrass grown on a calcareous light peat soil. The season was an unusually wet one, in contrast with the dry season experienced in 1949.

2. Seven successive cuts were taken during the season from each of two crops of ryegrass, one following a crop of marrow-stem kale, and the other a crop of celery. Different amounts of a general compound fertilizer had been applied.

3. Generally, the findings confirmed those of the previous year's investigation. High ground waterlevel (approximately 18 in. below ground surface) had a deleterious effect upon the yield and quality of ryegrass as reflected by its protein content, compared with the medium and low water-levels (23 and 30 in. below ground surface, respectively).

4. The high water-level also had a depressing effect upon the percentage of potassium and magnesium in the grass, but had no consistent effect upon calcium and phosphorus. The silica content rose steadily in all cases as the season advanced, as occurred in the previous year.

5. Residual manuring effects were well marked in the crop following celery. The total yields of dry matter from the medium and low water-levels considerably exceeded those of similar plots following kale, and the protein contents were also appreciably higher. This demonstrates the advantages of a high soil nutrient status, under conditions of suitable water-levels, for a crop of fenland grass.

6. A high water-level inhibited growth and quality, irrespective of the nutrient status of the soil.

A simple method to determine the expectation of selected minimum rainfall has been developed on the assumption that monthly or seasonal rainfall is normally distributed over a period of years. Although it is realized that a perfectly normal distribution cannot be obtained, practical experience has shown that the assumption leads to no serious discrepancies and the advantage of simplicity is considerable. A detailed example of its use to forecast the agricultural potentialities of dry lands is given.

1. The effects of various starch and protein supplements on the digestibility of cellulose determined by the Norman-Jenkins technique and other constituents of the ration were studied in sheep.

2. The addition of small amounts of maize or potato starch or flaked maize to a ration of about 1 lb. of poor hay was associated with a depression in the digestibility of (Norman-Jenkins) cellulose.

3. When tested separately at varying levels, the addition of nearly pure maize protein, casein, white fishmeal, decorticated groundnut cake meal, urea or urea + DL-methionine, had no effect on the digestibility of cellulose, at any particular level of starch equivalent.

4. The digestibility of nitrogenous nutrients was depressed by the addition of maize starch or flaked maize to the ration except when urea was the nitrogen supplement. The depression was even greater when potato starch was added to the ration instead of maize starch.

5. The retention of nitrogen was not decreased by the addition of starch to the ration, although the digestibility of nitrogen-containing material was depressed. The retention was increased when starch was added to a ration containing casein.

6. The retention of nitrogen was poor from rations containing urea and starch, but it was slightly improved by the supplementation with 1 g. DL-methionine per day.

7. The addition of the various supplements had no marked effect on the digestibility of the dry matter or ‘other nutrients’ of the ration.

8. It is suggested that the growth of the microorganisms digesting cellulose in the rumen is not dependent on the supplementary feed nitrogen when the substrate they are digesting contains a reasonable amount of nitrogen. This amount appears to be about 1%.

9. The addition of vitamins of the B-complex to a daily ration of 1100 g. of hay did not affect the digestibility of the dry matter or nitrogencontaining substances or the retention of nitrogen by sheep.

1. The resting heart rate of cocks and hens was measured in varying degrees of heat stress, and during acclimatization to heat.

2. When the rectal temperature was below 110°F. (43·3° C), the heart rate varied inversely with the severity of the climate up to an air temperature around 99° F. (37·2° C).

3. At air temperatures of 99° F. (37·2° C.) and above the heart rate was nearly constant over a wide range of rectal temperatures below 110° F. (43·3° C). It averaged about 50 beats/min. less than in an equable climate.

4. Above 110° F. (43·3° C.) there was an increase of about 30 beats/min./° F. (17 beats/min./° C.) rise in rectal temperature. The rate equalled that found in an equable climate, when the rectal temperature reached 111–112° F. (43·9–44·4° C). Over this zone of body temperature the fowls were often agitated.

5. In severe heat stress there was a slight fall in the heart rate on acclimatization, but this was small compared with the effect of climate.

6. In severe heat stress the heart rate during the day was slightly higher than that at night.

7. The relation of these findings to the mechanism of temperature regulation is discussed.

A uniformity trial on groundnuts has been analysed and the results discussed. Plant number is less variable than yield and less sensitive to shape of plot and of block. For yield, long narrow plots are more efficient than shorter and wider plots, in all shapes and sizes of blocks and in Latin squares. The plots should not be arranged end to end along the contours, but side by side, either singly or in pairs, forming compact blocks.

The regression of the plot variance of the mean yield per unit area on size of plot approximately follows a linear logarithmic relationship. A similar relationship holds for plant number. The value of the regression coefficient b′ is low and it has been shown that, as expected, there is considerable gain from the use of small blocks. The efficiencies of various confounded and incomplete block designs relative to designs in larger blocks have been determined for some particular layouts, and values for other layouts, ignoring shape of plots and of blocks, have been obtained by interpolation.

The field used for this uniformity trial appears equally variable in all directions.

Analyses of grass samples from seventeen fertilizer trials on acid soil showed that both the percentage phosphate in the grass and the amount of phosphate removed by the crop were significantly and directly related to the percentage saturation of the b.e.c. of the soil. The amount of acid-soluble phosphate by difference (Table 1, A — B) was also significantly and directly related to the percentage phosphate in the grass but not to the amount taken up by the crop. The amounts of exchangeable bases, exchangeable calcium and acid-soluble, adsorbed and watersoluble forms of phosphate showed no significant relationships with phosphate uptake and percentage phosphate in the grass.

The percentage saturation of the b.e.c. was found to be, on the average, about five times as effective a contributory factor to the percentage phosphate in the grass as the amount of acid-soluble phosphate by difference. The results confirm previous work, which indicated that in acid soils the main form of available phosphate is that associated with the exchangeable bases the effective presence of which is governed by the percentage saturation of the b.e.c. It is considered that phosphate availability and response in acid soils are best assessed by considering the percentage saturation of the b.e.c. rather than the amounts of some form or forms of phosphate in the soil.

The grass analyses also showed that when the amount of phosphorus (P) hi the dry grass exceeds 0·33% no response to phosphate is to be expected. When the percentage in the grass is less than 0·23% responses of 10% or more are likely.

A method is suggested for the quantitative description of the genetic structure of pedigree breeds of animals. Results are given for eight breeds, showing that the number of herds controlling effective breeding policy is in all cases small.

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. 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.

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.

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.

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.