1. The proximate analysis of a number of widely differing soil profiles has been carried out, employing a slight modification of the scheme used by Waksman and Shewan. This included a nitrogen fractionation with water and acid, similar to that of Waksman and of Shewan. It was supplemented by ammonia and nitrate estimations. The data are expressed on the basis of total organic matter.

2. The soils ranged in quality from peat and forest soils to grassland profiles. This gradation of quality was brought out by many of the figures of the proximate analysis. The better quality soils are associated with:

(a) a lower average content of fats and waxes, hemicelluloses and cellulose;

(b) a rapid decrease in cellulose with increasing depth;

(c) higher total nitrogen and various fractions, including higher ammonia and nitrate and a higher ratio of nitrate to ammonia;

1. An experimental study has been made of the effects of heat, light, air, enzymes and bacteria on carotene destruction, when green fodder is dried and stored as hay.

2. Carotene in green fodders can be destroyed by autoclaving or other forms of heating in the presence of air. The extent of destruction depends upon the period of heating.

3. Carotene is not destroyed if green plants are dried in a vacuum.

4. Atmospheric oxygen plays the predominant part in the destruction of carotene; and heat, light and moisture are merely accelerating agents. The destruction of carotene during storage is due mainly to a slow spontaneous oxidation of the pigment in plant material.

5. The utility in India of grass drying or hay making with the specific object of providing vitamin A supplements is questionable, because of the carotene destruction during storage under prevailing temperature and climatic conditions.

A water-culture technique has been described which makes it possible to determine with precision the effects on plant growth resulting from the absence of traces of the various heavy metals.

The essential nature of copper for plant growth has been confirmed, and the quantitative data presented show that the addition of traces of copper to a nutrient solution leads to increases of growth of the order of 200–1200%.

The characteristic symptoms produced by growing oats, peas, wheat, Wimmera rye-grass, Phalaris, flax, tomato, subterranean clover, and lucerne in nutrient solutions devoid of copper are described. Copper becomes necessary for normal healthy growth at an early seedling stage and is required so long as active growth is proceeding. Optimum growth of oats was obtained throughout a wide range of copper concentration in the nutrient solution.

Oats grown in a copper-free nutrient solution until the development of acute deficiency symptoms recovered and completed their normal life cycle on the addition of sufficient copper to the solution.

The copper content of oats at various stages of growth has been determined. The proportion of copper in the dry matter of the plant was greatest in the young stages and rapidly decreased as growth proceeded.

The copper content of mature oat plants showing symptoms of copper deficiency was less than 1·0 mg. per kg. whether grown in nutrient solution or obtained from copper-deficient soils. Oats which ceased growth from copper deficiency at an earlier stage of development contained a relatively greater amount of copper in their dry matter.

1. Increasing the ballast on pneumatic tyres, up to a certain weight, improves the tractor performance as judged by its speed, fuel consumption and wheel slip. Further increases beyond this point continued to decrease the wheel slip without having any marked effect on its speed or fuel consumption. No certain evidence was obtained that too heavy a ballast decreased the tractor's efficiency.

2. The tyre load affects the maximum pull the tractor can exert while working reasonably efficiently, but this pull does not depend markedly on the speed of work. Wheel weights of about 12–13 cwt. seem to be the minimum required for optimum performance of the 36 or 28 in. tyres at pulls of 1800 lb. under fairly good ground conditions, and possibly a greater weight may be required by the 24 in. tyre.

3. If the tractor is ploughing it is usually running tilted, and this tilt transfers sufficient weight on to the furrow wheel for it to work efficiently under most conditions. Additional ballast is, however, often necessary for the lighter land-side wheel.

4. Tyre performance is much less dependent on inflation pressure than on ballast. Pressures below 10 lb./sq. in. were only of use in wet conditions when small amounts of additional ballast were not available. Pressures above 12 lb./sq. in. may allow excessive slip to take place and probably only need be used on the furrow wheel of a well-loaded tractor ploughing.

1. The decomposition of the organic matter of four medium to large-scale composts has been studied by analysis of samples taken at intervals.

2. The bulk materials of the composts were grass-cuttings, oat-straw, Sphagnum peat and an Eriophorum and Sphagnum peat. All were made up to the same nutrient-content and relative water content.

3. The analytical method used was a modification of the scheme of proximate analysis used by Waksman and by Shewan. It was supplemented by ammonia and nitrate determinations, using Olsen's method.

4. Observations.

A. All composts.

(i) An increase in ammonia, water-soluble nitrogen and water-soluble organic matter took place during the first month.

(ii) Only low nitrate concentrations were developed.

(iii) Very closely parallel changes in H2SO4-soluble nitrogen and residual nitrogen were recorded.

(iv) Other nitrogen changes can be described as slight and on the whole as mutually compensating fluctuations.

1. A series of balance experiments to compare calcium carbonate, calcium sulphate and calcium gluconate as sources of calcium for laying hens is described.

2. Not one of the three supplements showed all-round superiority, but calcium sulphate was the worst.

3. The main results indicate that:

(a) Calcium sulphate and gluconate cause scouring but carbonate does not.

(b) The best retention of calcium occurs with gluconate and the worst with sulphate.

(c) Calcium carbonate gives the best shells and calcium sulphate the worst.

4. The experiments also throw fresh light on some more general aspects of calcium and phosphorus metabolism.

5. On the basis of these general results and a review of the literature of blood calcium and phosphorus in laying hens a theory dealing with certain aspects of egg-shell formation is presented.

The results of carotene metabolism experiments with four cows and four bullocks have been discussed. It has been shown that under ordinary farm diet, cows may secrete milk with a fair amount of carotene and vitamin A potency and still themselves remain on negative carotene balance, so far as the current intake and outgo are concerned. Increased intakes of carotene are, however, followed by the increased carotene and vitamin A potency of milk. Experiments with bullocks on a carotene-low diet consisting of dry rations have shown that the faecal carotene elimination attains a constant value and the animals show a consistently negative carotene balance. When, however, two doses of berseem are superimposed on this basal ration, positive retentions of carotene are obtained, followed by a rise in the blood-carotene level. The experimental evidence points to the possibility of a part of the faecal excretion being the result of a withdrawal of carotene from the body reserves.

1. A method of assessing the biological values of proteins by the slaughter method, using day-old chicks as experimental material, is outlined.

2. Whale-meat meal, when added to a cereal basal ration, is shown to possess a high biological value for chicks.

3. The method of preparation of animal proteins is shown to affect their nutritive value, whale meat dried at a low temperature giving better results than that dried at a high temperature.

4. The nature and amount of a protein added to a cereal ration materially affects the efficiency of utilization of the gross energy of the ration. Arising therefrom, support is given to the system of expressing the nutritive value of feeding stuffs, and the nutritive requirements of animals, in terms of digestible protein and digestible nutrients or metabolizable energy.

5. Outbreaks of feather picking in the whale-meat meal groups occurred, whereas none occurred in the basal group. A possible explanation for these outbreaks is given in the text.

6. The presence of gizzard erosion was noted in all individuals in the whale-meat meal groups, whereas none occurred in the basal group.

There are many areas throughout Britain where soil parent materials cannot be differentiated on the basis of solid geology alone, and difficulties are frequently experienced in classifying and mapping the soils. The object of this investigation was to study the parent materials and soils in a complex area of this kind.

The area selected is in north-east Scotland, and about half of it is covered by acid igneous and metamorphic rocks and the rest by sedimentary rocks of Old Red Sandstone age. The geology is complicated by three glaciations giving rise to diverse soil parent materials.

Five main groups of parent materials have been recognized, based on origin, texture and mineralogical composition. The first group consists of drift derived from acid igneous rocks and schists; the second of boulder clay from similar material plus an admixture of sedimentary rocks; the third of fluvioglacial deposits of varied textures; the fourth of conglomerate or thin drift from Old Red Sandstone rocks; and the fifth of boulder clay derived from Old Red Sandstone rocks where the influence of marls and shales in the drift is strong. Groups 1 and 5 are of major importance in this region and also elsewhere because of their widespread distribution. The others are more local.

The relative unreliability of Bouyoucos's suction method for moisture equivalent determinations is a consequence: (1) of the variation of the suction force maintained with the nature of the soil, (2) of bad reproducibility of the results.

Constant and equal suction for all soils is secured by Schofield's silt-suction method, which may also be made to give fairly well reproducible results. The moisture content at pF 2·9 determined by this method should give a fairly close measure of the moisture equivalent.

While investigating this possibility it was found that the pF curves of stored soil samples may shift considerably with time. In the samples studied the pF at the moisture equivalent has dropped from 2·9 to about 2·4 in 7 years. In view of this shifting the reliability of the silt-suction method for moisture-equivalent determinations has not been definitely ascertained by the experiments reported.

A modified method of estimating the carotene content of plant material has been described in detail. The modifications include a combined aqueous and alcoholic potash hydrolysis of the original material before extraction is carried out.

A statistical analysis and a recovery test have shown this method to be relatively more efficient than methods similar to those described by other workers.

1. The question of the maintenance requirement of calcium for poultry is discussed.

2. On the basis of curves relating intake of calcium to calcium in the droppings, a maintenance value for laying and non-laying birds is estimated.

3. It is suggested that in the case of both laying and non-laying birds the maintenance requirement of calcium is about 0·10 g. and that the endogenous calcium value is about 0·05 g.

In April 1938 I published a method for the determination of carbon in soils (Alper, 1938). This method consists of digesting the soil with a mixture of sulphuric acid and potassium bichromate, passing the products of combustion through a heated combustion tube and absorbing the carbon dioxide produced in barium hydroxide. Digestion and absorption take place in a closed system which allows neither the escape nor entrance of carbon dioxide. The absorption flask is evacuated and separated from the digestion flask by a glass tap. During the process of digestion, as the pressure in the system increases, this tap is manipulated, allowing the escape of gas into the absorption flask. A pressure gauge in the system indicates when the tap should be opened.

The sensitivity of this mercury pressure gauge causes some difficulty in technique. It is necessary to watch the experiment throughout the digestion and to manipulate the tap constantly. In order to obviate this difficulty an improvement in the apparatus has been effected. The pressure gauge has been replaced by an elastic bladder (a child's balloon serves the purpose admirably) which is connected to the system by means of a glass ┬-piece. At the commencement of the experiment the pressure within the system is slightly less than atmospheric owing to the suction of CO2-free air through the apparatus. This causes the complete deflation of the balloon. As digestion continues the balloon becomes distended. The distension of the balloon must not be allowed to go too far as too great a pressure in the system will result in losses through leakage.

1. Under artificial conditions of plant growth, the relative development of carotene is very poor. The absence of sunlight appears to be the main cause.

2. Under field conditions, the maturity of a plant plays an active part in determining the carotene content, which gradually decreases with age. This phenomenon is less discernible among the legumes. The nitrogen content generally runs parallel to the carotene.

3. The species of the plant seems to be a determining factor in the capacity of the plant for carotene formation.

4. A study of the distribution of the carotene in different parts of the same plant shows that the leaves of grasses contain 3·1–11·0 times more carotene than the stems. The earheads and stems have almost equal amounts. With the growth of berseem and lucerne, the ratio of carotene in leaf to carotene in stem shows a tendency to increase, suggesting that the deterioration in the stem is comparatively more rapid than in the leaves when the plant becomes older.

1. An individual feeding experiment using forty-eight pigs and a group feeding experiment using twenty-nine pigs have been carried out with the object of testing the so-called Lehmann system of pig feeding, where the amount of meal allowed for the fattening pig is restricted to a basal ration of 2½ lb. each and farm bulky foods or food wastes fed ad lib. used as supplementary foods.

2. Using a mixture of 6 parts mangold and 1 part biscuit waste as a supplementary food, live-weight gains only slightly less than with all-meal feeding have been obtained and a great saving in meal consumption effected. Under more favourable conditions as much as 1¾ lb. of meal has been saved for each 1 lb. live-weight gain.

1. The mean pH of 221 ejaculates of clinically normal bulls was 6·73 ± 0·020. Significant differences were noted between different bulls.

2. There were highly significant negative correlations between the pH. of the ejaculates and the concentration of spermatozoa, the volume of ejaculate and the motility of the spermatozoa.

3. The more acid the semen was on collection, the better was the motility retained on storage. Semen which retained its motility well became increasingly acid during storage. A change in the pH in the alkaline direction during storage had an adverse effect on motility. The more acid the pH on collection the less likely was a decrease in acidity during storage.

1. Results obtained from two seasons' population studies of selected spring oat varieties in Scotland indicated that extent of tillering had little or no effect on yield. These results are in sharp contrast with those obtained by workers with wheat.

2. The yield of individual plants under the conditions of the experiments became adjusted to differences in population density primarily by variation in number of grains per panicle. Spikelet weight tended to be negatively correlated both with population density (external competition) and with number of grains per panicle (intrapanicle competition). These factors tended to neutralize each other.

3. The decrease in size of additional grains in spikelets with more than one grain was balanced by increased weight of the basal grains as compared with the weight of a single grained spikelet. Average grain weight per spikelet therefore tends to remain constant.

Rotation of crops is based in most countries upon the accumulated experience of past years; experiments testing the relative merits of various rotations are rarely resorted to unless some serious disturbance arises, such as the inclusion of a new crop. But in the Sudan Gezira (lat. 14–15° N., long. 33–34° E.) the need for rotation experiments was urgent, since growing cotton by artificial irrigation was a recent introduction, and, moreover, the soil was known to be intractable. Any improvement in rotation which would allay seasonal fluctuation in yield and raise the general level would greatly add t o the prosperity of the area.

Thus when the Gezira Research Farm was inaugurated in 1918 some unreplicated plots of various two-course rotations, and of continuous cotton, were laid down. These were supplemented in 1925–6 by a replicated trial comparing various three-course rotations, designed by E. M. Crowther of Rothamsted. Later, in 1931–2, a new ‘Combined Rotation’ experiment, designed by M. A. Bailey and E. M. Crowther, was added, and this comprised comparisons of one-, two-, three- and four-course rotations. These last

An account has been given of recent work on the chemical nature of war-time swill and on the best methods of using this product so as to ensure the maximum replacement of concentrates, consistent with economical live-weight gains, in the rations of bacon pigs.

Three different types of swill have been submitted to investigation: (1) a meat-rich military camp swill, characteristic of the material available during the first 18 months of the war; (2) processed urban swill, commonly known as concentrated swill; and (3) dried, balanced swill. In addition, the results of an investigation into the variation in composition of household and restaurant swill are also given.

The different types of swill have been examined from the standpoints of (1) main ingredients, (2) chemical composition, both organic and mineral, (3) digestibility, when fed to bacon pigs, and (4) nutritive value in comparison with mixtures of common pig foods. The keeping qualities of processed urban swill and dried, balanced swill have also been investigated, and attention has been devoted to the problem of the seasonal variations of urban swill in respect of main ingredients, chemical composition and feeding value.

1. Gonadotrophic extracts of horse-pituitary gland, of pregnant mare serum and of urine of pregnant women, as well as oestrogenic substances, will induce ovulation in anoestrous sheep. The number of ova shed is apparently independent of the dosage given and lies within the normal range.

2. The oestrogens probably act by evoking ovulation-producing activity on the part of the animal's own pituitary gland, and it is likely that the gonadotrophins also initiate the same chain of events by causing oestrogen secretion by the ovary.

3. Oestrogens induce heat in the anoestrous sheep, but horse-pituitary extract and P.M.S. evoked sexual receptivity only in animals having a regressing corpus luteum. In the absence of a corpus luteum, ovulation occurs without heat, while the presence of an active corpus luteum usually suppresses both ovulation and heat.

4. Administration of horse pituitary a few days before the corpus luteum is due to regress results in superovulation at the succeeding heat, as many as twelve simultaneous ovulations having been obtained under these conditions.