1. An experiment was performed to obtain information on the fluctuations in excretion of calcium, carbonate, phosphorus and chloride within the day.

2. It was found that there was a lower excretion of calcium and carbonate in the 12 midnight–8 a.m. subperiod than in the 8 a.m.–4 p.m. and 4 p.m.–12 midnight subperiods. Phosphorus showed a much smaller variation, whilst chloride gave inconsistent results.

3. When eggs were laid there was a distinct increase in phosphorus and chloride excretion and a fall in calcium and carbonate excretion. These changes, although related in time to each other, were not clearly related to the time of oviposition. Thin-shelled eggs did not give the same results, much smaller changes being observed.

4. When changes were made in the amount of calcium carbonate added to the basal ration the effect on the composition of the excreta was noted within 4 hr., the full effect showing itself within 16 hr.

5. The significance of these results in relation to egg-shell formation is discussed.

The dry-matter content of about 260 samples of potatoes was determined. The samples were collected over three seasons and from many types of soil.

The average dry-matter content of a variety varied from season to season, but it always bore an approximately constant relationship to the average value of other varieties.

Wet seasons led to potatoes low in dry matter.

The variation in the content of dry matter of potatoes in different seasons and from different soil types is not a direct effect of the water balance of the tubers.

The average content of dry matter of potatoes depends on the soil in which they were grown; fen and blackland gave potatoes with the lowest dry matter, followed by skirt, silt and warp, then loam and medium loam, then clay, and the highest dry matter occurred in stocks grown in sands, gravels or light loams.

The difference between the soils is discussed, and it is tentatively concluded that the factor responsible for the variation in content of dry matter of the potatoes is the available water content of the soils.

1. The influence of different levels of dietary calcium upon egg-shell thickness and uniformity of egg-shell thickness is discussed.

2. The low calcium diet caused a gradual thinning of the shell, but no soft-shelled eggs were laid.

Two large-scale feeding trials have been carried out with the object of testing the validity of findings from pig digestion trials in respect of the nutritive value of horse-chestnut residue (a by-product of the manufacture of saponin and glucose from horse-chestnuts); and of alcohol-extracted and water-extracted horse-chestnut meals.

Trial I. The horse-chestnut residue was fed in two separate periods, the first from 50 to 100 lb. live weight, when the residue constituted 20 % of the total ration, and the second from 190 lb. to slaughter weight, when the allowance was increased to 30%. In both periods the residue replaced an equal percentage of ground oats in the control ration.

Samples of potatoes were collected in three successive seasons from a wide range of soil types and their liability to stem-end blackening determined.

Variety and season of growth affected the amount of stem-end blackening which developed.

All soil types gave samples with a wide range of stem-end blackening, but the average amounts of blackening in samples from different soil types were shown to differ significantly. Samples from fen, blackland, sand, gravel, limestone and chalk blackened more than those from skirt, silt, warp, clay and boulder clay.

The pH of the expressed sap of tubers was independent of the type of soil in which they were grown, but dependent on variety and locality of growth. No evidence that the pH of the tubers influenced the amount of stem-end blackening pigment was obtained.

The yellowness of the flesh of tubers showed an approximately normal distribution. Slight evidence for an effect of soil type on the amount of yellow pigment was obtained.

The work described above was carried out as part of the programme of the Food Investigation Board of the Department of Scientific and Industrial Research.

1. A field experiment in which ninety-seven farms co-operated has been carried out to find whether giving cows a daily dose of 20 g. of iodinated casein, incorporated with an additional allowance of concentrated food, could be used to increase milk yields for short periods on commercial farms. The results have been analysed statistically, and the causes of variation in the response to iodinated casein have been investigated. The farms supplied 1164 cows, and 1008 cows were finally included in the analysis. Not all of the seventy-eight pairs which were deleted were discarded, and some could legitimately be used in certain parts of the analysis.

2. 4% of the cows refused the iodinated casein cube. The refusal rate was higher in the Channel Island cattle which are known to be fastidious feeders

1. One laying and one non-laying bird were fed a normal calcium ration, and one laying and one non-laying bird were fed a low calcium ration. Four hours after feeding the birds were killed, and the contents of the various portions of the alimentary tract were analysed and compared with the composition of the original food.

2. The pH of the crop contents is influenced by the pH of the food. The lowest pH value is given by the gizzard contents, but after that there is a gradual rise, until, by the time the 4th segment of the small intestine is reached, the pH. is almost constant at about 6·8 for all birds.

A convenient method of introducing into a field experiment additional factors which can be applied to smaller areas than that of the whole plots is to use split plots: each whole plot is split into sections, and the different combinations of the additional factors are randomized over each set of sub-plots. An extension of this idea is the device of split-plot confounding, by which not all the combinations of the additional factors are used in every whole plot; instead, the possible combinations are subdivided into two or more sets which are then assigned to blocks and whole-plot treatments in a balanced manner, in such a way as to confound certain interactions of the additional factors between whole plots and certain higher order interactions between blocks.

1. The daily retention of calcium, carbonate, phosphorus and chloride was studied using four birds and changing the calcium carbonate content of the ration every 5 days for 15 days.

2. It was shown that high calcium diets result in a much lower retention of calcium and thin-shelled eggs are produced.

3. Retention of calcium was higher in the laying than in the non-laying bird when calcium carbonate was fed.

4. High calcium diets depressed the retention of phosphorus, and in one case the retention was negative, even when no eggs were laid. Laying birds gave negative values for retention because of the heavy phosphorus excretion associated with egg laying.

5. High calcium diets also depressed the retention of chloride, and on occasion led to negative retention values.

The device of split-plot confounding for introducing additional factors into a field experiment can only give a balanced design when the number of whole plots per block and the number of replications of each whole-plot treatment are multiples of the number of sub-sets into which the combinations of the additional factors are divided. When this condition is not satisfied it may still be possible to arrange that the design shall be partially or nearly balanced in such a way as to be useful in practice and to require a reasonably simple statistical analysis. Nevertheless, the experimenter should always bear in mind the desirability of balance, and should have recourse to unbalanced designs only when the exigencies of space or material, or an unforeseen necessity of introducing extra factors during the course of an experiment, leave him with no alternative. No attempt has been made to give a comprehensive account of designs of this kind, but the numerical analysis of the yields from a typical experiment has been discussed in detail. Though the lack of balance leads to some non-orthogonality of treatment contrasts, the more important comparisons can usually be satisfactorily estimated. The details of this estimation vary from one experiment to another, but the example given should make the principles clear to those who are familiar with the analysis of variance. I am indebted to Dr E. M. Crowther and to the Agricultural Research Council for permission to use the numerical results discussed in this paper

The general characteristics of a group of thirtynine herds of dairy cows in the Eastern Counties of England, and the method of obtaining information about their diet during the winters 1938–9 to 1942–3 inclusive, are briefly described.

The first three winters of the war show a continuous decline in starch equivalent and protein equivalent per cow, followed by a recovery during winter 1942–3.

Comparing winter 1942–3 with winter 1938–9: Consumption per cow of concentrates declined by one-third, reductions in proprietary compounds and mixtures and in maize and wheat products being outstanding.

The more important increases were in oats, straw and succulent foods, notably mangolds, sugar-beet tops and kale.

Hay retained its important place with little overall change; a modest increase in silage was restricted to a few herds.

The crude weight of the average daily ration increased from 44 to 61 lb., but its dry matter only from 21·0 to 22·6 lb.

The residue: total dry matter less digestible organic matter—increased from 7·2 to 8·4 lb. per cow daily. Reference is made to changes in palatability.

Studies on the feeding of cyclized vitamin A, vitamin-A alcohol, and vitamin-A ester (as cod-liver oil) to chicks receiving a diet of c. 13% protein content, show that chicks do not assimilate cyclized vitamin A and only begin to assimilate vitamin-A alcohol and vitamin-A ester between the 35th and 42nd day, when the results of analytical methods employed to evaluate carcass and liver stores of these substances are used as criteria, or when growth is used as criterion.

Studies on the feeding of green food and yellow maize, as sources of provitamin A, and vitamin-A alcohol, to chicks receiving a diet of c. 17% protein content, show that chicks do not utilize these substances until between the 35th and 42nd day, when the results of analytical methods are employed as criteria of assessment of vitamin A storage in carcass and liver, or when growth is used as criterion.

1. The changes which have occurred in the nutrition of young dairy stock are discussed. It is emphasized that any food shortage of a farm affects young cattle before the rations of the cows are reduced.

2. An estimate of minimum protein level is developed using Mitchell's (1926) method.

3. An experiment designed to show the optimal level of protein in the ration for growing stock showed a difference between this minimum estimate and the optimal. Some considerable economy in protein can, however, be effected in Wood & Woodman's (1936) standard is the one normally used to calculate rations.

4. The growth of young cattle on protein supplemented wartime dietaries of straw is shown to be below that of heifers fed the rations more normal in peace time.

5. Stunted cattle undergrown by 7–8 months when 18 months to 2 years old have been found. This has been attributed to the effects of wartime rations.