Using data from a blank experiment with wheat it was found that the regression of the logarithms of the variances for plots of different areas on the logarithms of their areas was approximately linear. A graphical review of variances, etc., reported in the literature for thirty-nine other blank experiments indicates that the results of most such experiments conform to the same law.

It is shown that the above law can be generalized (so as to be applicable to any size of field) by applying a certain adjustment to the regression coefficient b', so as to give a modified coefficient b applicable to an “infinite” field.

From this generalized relationship there has been deduced an expression ((4), p. 16) to indicate average relative efficiencies to be expected for randomized block experiments with varying numbers of plots per block in a field for which the coefficient b is known.

A formulae (5), which may be used to estimate the most efficient size of plot for any given experiment, has also been deduced. The cost of using plots of other than the most efficient size is indicated graphically in Fig. 7.

1. An experiment on pullets combining daily calcium and phosphorus balance determinations with carcass analyses is described.

2. It is shown that fat content of pullets is affected by the calcium content of the ration. The fat content was higher on a low calcium ration than on a high calcium ration.

3. The CaO content of pullets was raised considerably by feeding a high calcium ration before laying. This CaO must have been stored in the bones, which contained between 97·2 and 98·7% of all the CaO in the body.

4. The experiment suggests that pullets may use up to about one-quarter of their body calcium at the outset of laying for purposes of shell formation.

5. The composition of the inorganic material of the skeleton of pullets may be modified by alterations in their mineral metabolism due to egg production on diets with and without a calcium carbonate supplement. The nature of these modifications and their relationship to calcium metabolism during laying is discussed.

1. From an examination of thirty-five soil samples collected in Furneaux & Glasscock's survey of pea soils of the Romney Marsh area of Kent it was shown that the Marsh Spot disease of peas is more closely related to soil reaction than to soil series or soil texture. The disease was not found on any acid soil but was present on most of the alkaline soils.

2. Most of the Romney Marsh soils contained appreciable amounts of free oxides of manganese and of salt-soluble manganese. The soils with Marsh Spot contained less salt-soluble manganese than those on which peas were free from the disease, but this relation depended essentially on the contrast between acid and alkaline soils. Within the alkaline group of Romney Marsh soils, however, analyses for salt-soluble manganese did not always distinguish between contrasted soils; three of the five alkaline soils on which peas were free from the defect were low in salt-soluble manganese.

3. A single extraction with normal calcium nitrate proved as effective as Steenbjerg's series of leachings with normal magnesium nitrate in characterizing the soils. Dilute acids dissolved more manganese than salt solutions. Citric acid gave higher results through reducing the oxides of manganese. The acid-soluble manganese was not related to the occurrence of Marsh Spot.

4. Soils on which oats suffered from Grey Speck disease and sugar beet from “Speckled Yellows” contained little or no salt-soluble manganese. Applications of manganese sulphate, which controlled the diseases in the field, appreciably increased the salt-soluble manganese in the soils.

5. Peas grown in pot cultures in manganese-deficient soils and in a sand-bentonite mixture developed Marsh Spot. Addition of manganese sulphate increased the manganese content of the seeds, especially in sand-bentonite, and controlled the disease.

1. From an analysis of the records from 702 cattle of predominating Jersey type tested for at least six consecutive years under normal and average herd conditions in New Zealand, the authors have attempted a detailed study of the nature of the increase in production according to age.

2. They are unable to find any evidence supporting the theory that increase in production for dairy cattle operates as a percentage addition from early age to maturity.

3. The evidence secured from an analysis of 702 Jersey records of six consecutive lactations commencing at 2 years of age, strongly suggests that the increase in production according to age can be summarized neither by a percentage addition nor a constant addition alone, but is best represented by a regression formula of the nature X = aY + b, where X equals the maturity production and Y the immature production.

4. The strict regression formula will probably change according to the interpretation of “maturity equivalent”, but in general its application should lose little of the simplicity of the ratio form of conversion.

1. The porosity of egg is measured by the usual practice of estimating the weight loss under standard conditions. The porosity coefficient is expressed as the loss in weight in mg. per sq. cm. of egg surface per 24 hr. at 37°C.

P coeff.=mg. cm.2 24 hr. 37°.

2. It is shown that eggs of even curvature approximate closely to the ideal mathematical form of two hemi-prolate spheroids, differing in their eccentricities and meeting in the plane of their common minor axes. On this assumption the divergence between the observed and calculated long perimeter is only +0·618 per cent (five eggs) and between the observed and calculated volumes+3·78 per cent (seventy eggs).

3. It is explained how, by taking the specific gravity of the egg to correct for departures from the theoretical form, it is possible to calculate the surface area with an error not exceeding 1 per cent.

1. The method described in an earlier paper for measuring the compressibility of soils in situ has been used to study the gradual consolidation of soil following digging with a fork, and a new method in which the rate of flow of water through rubber tubes buried in the soil gives a measure of compression, is described.

2. By means of this latter method some measure can be obtained of the changes that take place in the soil after it has been loaded and trampled.

3. The results of the experiments confirm and amplify the earlier conclusions. Without further data it is hard to distinguish quantitatively the effects of moisture and time, but it is of interest that whereas the compressibility of newly dug soils is hardly affected by differences in moisture for the range of stress used, that of soils which have rested for some time since cultivation is much increased by an increase in moisture content.

4. Experiments on a wider scale should be undertaken in order that a more complete analysis may be effected.

1. Inaccurate results previously obtained with wet-combustion methods for the determination of carbon in soils have probably been due to: (a) incomplete oxidation of carbon; (b) incomplete absorption of carbon dioxide. The method described herein ensures complete oxidation and complete absorption. The oxidizing agent employed consists of a mixture of sulphuric acid and potassium bichromate; the absorption takes place in a closed system.

2. When highly accurate results are required, a combustion tube is a necessary adjunct to the wet-combustion method, as appreciable amounts of carbon escape complete oxidation in reaction flask.

3. The soil should be moistened with water before adding the oxidizing mixture, to avoid the formation of complexes, which may protect part of the carbon from oxidation by the acid.

4. Within limits, the concentrations of sulphuric acid and potassium bichromate do not affect the results.

5. While it is necessary to use catalysts (selenium and potassium sulphate) for the complete oxidation of the resistant carbon of coal, catalysts were found to be unnecessary for the determination of carbon in soils.

6. For soils rich in chloride, it is necessary to absorb the chlorine evolved by means of sodium bisulphite solution.

1. A study has been made of the relative development of some regions in the fleece of twin lambs of a Suffolk ♂ × Suffolk (Border Leicester-Cheviot) ♀ cross during growth. The different regions develop in the following order: shoulder → leg → belly → tail. It is concluded that an improved animal is one in which the latest developing part of the fleece has the least possible number of undesirable fibres at the earliest possible age. The breeds of sheep begin their wool improvement by changes in the earliest developing regions (shoulder) and finish it in the latest (tail).

2. The properties of the fleece studied were the colour of the fibres, the medullated fibres, the fineness of the fibres, and uniformity of fibre size. In general a relationship is found between the stage and rapidity of development of the area, and the properties of the fibre. The intensity of the colour is stronger during the early active stages of development. There is a tendency to lose some kinds of coloured fibres, and to diminish the intensity of the colour in others as the development of each region in which the fibres grow proceeds.

The medullated fibres appeared in greatest quantities in the later developing regions, except the belly which presents few medullated fibres.

The staple is much finer at the first month of growth than in the later stages. Frequency curves of fibre size are of more value than average fibre size in estimating the value of the fleece.

3. It is suggested that the examination of the fleece of the lamb will give some idea of its genetic constitution and will reveal defects which would be concealed in the adult. Such a “phaeno-genetic” selection can be made best in a “late developing” area of the body such as the tail of the lamb at one month old.

1. A description is given of an adaptation of the Latin square lay-out to experiments with dairy cows. Experiments were conducted to test the effect of adding various fats and oils to the ration, and since effects were rapidly produced the Latin square technique proved very efficient, experimental errors being rather lower than those usually obtained in experiments with crops.

2. Seventeen separate experiments, including, in all, twenty-one different cows (many of whom were used more than once), were conducted; fourteen of these were short-term experiments with unit periods of 5 days, two were medium-term with unit periods of 10 days and one long-term with 20 days.

3. Palm oil, butter, lard and possibly cotton-seed oil were found to increase butterfat yield, chiefly by raising the butterfat percentage of the milk. Soya-bean, linseed and whale oils were without effect. Cod-liver oil definitely decreased butterfat percentage and butterfat yield.

4. It appears that the beneficial oils are those containing a large proportion of the saturated fatty acids.

5. Experiments with the same oil were not always consistent, and it appears that the effect may vary from cow to cow, and also with the same cow at different times.

Further studies of the behaviour of cellulose-splitting bacteria in artificial media have been made in an attempt to account for the manner in which cellulose is utilized for fat production in the ruminant. The behaviour of thermophilic bacteria, with an optimum temperature of fermentation in the neighbourhood of 65°C, has been compared with that of the micro-organisms capable of fermenting at 37°C. In both cases the cultures were obtained from the rumen contents of sheep.

By the addition of toluene at the “head” stage of fermentation, it was possible to demonstrate, both at 37 and 65°C., the production of small amounts of glucose during subsequent incubation. Glucose is clearly a primary breakdown product in the bacterial fermentation of cellulose.

An investigation has been made of the nature of the volatile fatty acids produced by bacterial decomposition of shredded filter paper. No consistent differences from this standpoint were noted between the reactions as carried out at 37 and 65°C., but the nature and proportions of the acids varied considerably from culture to culture. In some cases acetic acid was produced almost exclusively, whilst in others the fatty acids consisted of butyric and formic acids, with but traces of acetic acid. The findings in this regard apparently afford no clue to the manner in which cellulose is used for fat production, since propionic acid, the only recognized fat-former among the lower normal fatty acids, was not detected.

Individual analyses of forty Light Sussex cockerels of twenty-two weeks of age yielded the following results:

1. There is a highly negative correlation between the fat percentage of the carcass and the moisture percentage.

2. Owing to the large variability in the fat content of individuals, live-weight increases are unreliable as a measure of energy storage.

3. Comparison of the fat content of the bones with that of the flesh and offal leads to the conclusion that the bones as well as the flesh and offal play a significant role in the general fat metabolism of the body.

4. There exists a strongly positive correlation between the ash content of the bones and that of the flesh and offal.

5. The protein ash ratio of both the Light Sussex breed and the White Leghorn breed is practically constant for all individuals after the age of seven weeks, indicating that the growth of the skeletal and the muscular tissues are closely correlated and controlled by the same growth impulse.

6. The individual variation in energy content is shown to be ± 11.42% of the total energy content.

The results of an experiment, conducted over one cycle of a four-course rotation to study the effects of nine nitrogenous fertilizers on crops and soil, are described.

All the crops gave fairly good responses to nitrogen but in no case was there a significant difference between the effects of the various nitrogenous fertilizers. The “recovery” of added nitrogen was about 40–50 % with all the fertilizers.

Figures are given for the changes in exchangeable CaO content of the soil. The results confirm Crowther and Basu's deduction that “the loss of calcium exceeds that for equivalent nitrogen added as nitrate by an amount equivalent to the excess of anions over the cations in the added fertilizer, all added nitrogen being regarded as nitrate and all carbon and phosphates being ignored”.

The fact that phosphate should be ignored is shown by results for mono- and diammonium phosphates. Precipitation of phosphates in the soil almost certainly involves removal of calcium from the exchange complex but the calcium in such precipitated phosphates is exchangeable.

Since phosphate has no effect on calcium status, it is clear that fertilizers based on ammonium phosphates remove less calcium from the soil than do mixtures based on ammonium sulphate and superphosphate.

The low temperature ignition of soil organic matter has been investigated for temperatures ranging from 100 to 500° C.

Appreciable losses are found to occur below 100° C.; up to 200° C. heating results essentially in the distillation of volatile constituents, while between this temperature and 300° C. destructive distillation is the major reaction. These reactions are responsible for the removal of 85% of the soil organic matter.

By 300° C. the greater part of the residual organic matter consists of carbonaceous material, and the final reaction is simple ignition of this material.

Two hours’ heating of the soil at 450° C. or about half an hour at 500° C. are recommended for the removal of 99% of the soil organic matter.

When a set of experiments involving the same or similar treatments is carried out at a number of places, or in a number of years, the results usually require comprehensive examination and summary. In general, each set of results must be considered on its merits, and it is not possible to lay down rules of procedure that will be applicable in all cases, but there are certain preliminary steps in the analysis which can be dealt with in general terms. These are discussed in the present paper and illustrated by actual examples. It is pointed out that the ordinary analysis of variance procedure suitable for dealing with the results of a single experiment may require modification, owing to lack of equality in the errors of the different experiments, and owing to non-homogeneity of the components of the interaction of treatments with places and times.

The chemical composition of eight samples of fresh material and ninety-one samples of different kinds of silage has been determined. The crude protein varied from about 10 to 20 %. Judging by the appearance and edibility of the material, the silage samples made by the A.I.V. process were almost uniformly good. Their pH values were mainly between 3·5 and 3·8, and they contained less volatile acids and volatile bases than the other silages, and showed the highest proportions of lactic to acetic acid and amino-acids to volatile bases. The results as a whole show a fairly close agreement between pH., volatile acids and volatile bases, but attention is directed to the possibility of anomalous figures when, through secondary changes, the pH value has risen to about 6 or 7.

Thirty-one laporotomies, in addition to a number of confirmatory operations, were performed to determine the time of ovulation in the ewe. It was found that (1) ovulation did not occur during oestrus, (2) in ewes with oestrous periods lasting 30 hr. or more ovulation occurred a short time after the end of oestrus and that the time of its occurrence is related to the end and not to the beginning of oestrus, and (3) there is a minimum period of approximately 23–25 hr. before which ovulation does not occur, irrespective of the duration of oestrus.

When this investigation was begun in 1929, the conception of intensive grassland management, involving rotational grazing and the liberal use of manures, including artificial nitrogenous fertilizers, was just coming into prominence in this country. It had become necessary to secure information about the improvement of yield and composition of herbage that could be brought about by such a system of management, since somewhat extravagant claims were being made for the magnitude of the effect of sulphate of ammonia and other soluble nitrogenous manures on the yield and composition of pastures.

1. In two experiments on heavy land (one continued for four, and the other for three years) gyrotilling has been compared with normal cultivations, and no significant increase in yield has been obtained, although in five out of seven experimental crops the actual difference was very slightly in favour of gyrotilling.

2. In two experiments on light land (one continued for three, and one for two years) gyrotilling has been compared with normal cultivations (ploughing and subsoiling, and also, in one case, ploughing alone), and in all five experimental crops there was a slight depression in yield, which was only significant in one case, connected with gyrotilling.

1. In an examination of Park Grass soils extending over 3 years, and in shorter studies of other grassland soils, the fresh soil always contained more ammonia than nitrate nitrogen. The levels of both were low, and in spite of minor fluctuations were sufficiently constant to suggest the existence of equilibrium conditions in the nitrogen cycle. Climatic factors had no appreciable influence except on one very acid plot; here frost or drought, severe enough to kill the herbage, allowed ammonia to accumulate. Otherwise, treatment had little effect, but liming tended to give higher ammonia and lower nitrate levels. The equilibrium levels of both ammonia and nitrate were higher in old grassland soils than in land newly put down to grass.

2. “Mineralizable” nitrogen, produced by incubating the fresh soils under standard conditions, showed a seasonal rhythm the opposite of the annual temperature rhythm, tending to a maximum in winter and early spring and a minimum in summer and early autumn. This was related to the addition and decay of organic residues in the soil. An abnormally dry summer caused a temporary rise, especially on the more acid plots. An extremely acid plot, on which a mat accumulated in the field, produced as much mineralizable nitrogen on incubation as more normal soils.

3. Ammonia and nitrate production on incubation differed greatly with different treatments, apparently as a result of the influence of treatment on soil reaction. The more acid soils, with pH less than 6.0, produced chiefly ammonia, while the less acid soils produced chiefly nitrate. There was a significant correlation between reaction and percentage nitrification.

1. Wheat, barley or mangolds gave nearly the same yield if grown on seed beds prepared by ploughing and harrowing, by using the grubber or cultivator and harrowing and by using the Rototiller, provided that the cultivators were used for one year only. If used for several years in succession deterioration of yield sometimes sets in, possibly due to the increased weediness of the non-ploughed plots.

2. There was no advantage in ploughing deeper than 4 in. but it is advantageous to use the grubber of Rototiller deeper.

3. The effect of cross-ploughing, subsoiling or heavy rolling the seed bed for spring-sown crops was without effect on the yield.

4. Spring rolling and harrowing improved the yield of winter wheat but had little effect on the yield of straw. Rolling alone may have produced a slightly increased yield of grain but it improved the straw yield while harrowing depressed the straw yield.

5. There was strong evidence that intensive hoeing of sugar-beet or kale is detrimental. Two to three hoeings appear to be ample.