Continuous records of the temperature of potatoes stored in clamps were made in 1942–3 (one clamp) and in 1943–4 (three clamps). In the first year, the temperatures at various positions in the clamp coverings were also recorded.

The temperature at the middle of the potato heap showed a drift with time similar to that of mean air temperature. Deviations of mean air temperature from smooth trend, lasting for about a week, had no effect on the temperature of the potatoes; longerperiod deviations were reflected in the temperature of the potatoes after a lag of about a week. The difference in weekly mean temperature between potatoes and external air averaged about 1–5° C. in 1943–4. In 1942–3 it was greater, increasing to over 20° C. in April, because bacterial rotting of the potatoes following blight infection increased the rate of heat production and caused the clamp to collapse at the end of April.

Seven different experiments over 3 years and involving a total of 1750 ewes have been designed to study the effects of high and low levels of nutrition during pregnancy and during lactation on grazing sheep. The trials were run as nearly as possible under typical fat-lamb producing conditions. Commencing with breeding ewes in average store condition before tupping, a live-weight gain of 25–40 lb. from tupping to lambing was adopted as a standard of a high level of feeding and a gain of ± 5 lb. was considered to be a low level of feeding. Differential feeding was obtained by keeping the ewes on high-quality pasture as a high level of nutrition, and by stocking heavily on poor pasture as a low level. Under these conditions the following results were obtained:

(1) Level of nutrition during pregnancy. The high level of nutrition during pregnancy increased birth weight by about 0.5 lb., but had little if any influence on the rate of growth and the weaning weight of the lambs, irrespective of the subsequent level of nutrition. The high level did not reduce ewe and lamb mortality and there was some evidence to the contrary when the high plane was applied early, leading to large live-weight gain.

1. In the previous paper of this series (Callow, 1949) a special method of graphical analysis was developed in order to calculate the effect of different rates of fattening on the percentages of fatty tissue, muscular tissue and bone, etc., in a carcass. This method has been used in the present paper to calculate the effect of different rates of fattening on the deposition of chemical fat and protein in the fatty and muscular tissues of a carcass during fattening.

2. The method of analysis depends (a) on the choice of an arch-type carcass on mathematical and biological grounds, and (b) the use of partition percentages for defining the proportions of fat, protein and water laid down in the fatty and muscular tissues during an increase in carcass weight due to fattening.

The CO2 concentration in the atmosphere of a potato clamp varied between 0·06 and 0·86%. The sum of CO2 and oxygen concentrations remained approximately constant at 21%. The CO2 concentration increased with time from December to April. This was attributed to increase in the rate of respiration of the potatoes caused by rise of temperature. Wind blowing in the direction normal to the face of the clamp reduced the COa concentration, presumably by causing external air to flow through the clamp coverings. A multiple regression of CO2 concentration on temperature of the potatoes at the time of sampling, and on the mean component of wind velocity normal to the clamp face estimated over a period of 3 hr. before the time of sampling, accounted for 64% of the variance between sampling occasions.

Unsaturated compounds were detected in the clamp atmosphere by absorption in bromine; the concentration of these, expressed as ethylene, varied between 0·004 and 0·025%.

The magnitude of CO2 accumulation and oxygen depletion in the clamp atmosphere was too small to produce effects of practical importance on the storage behaviour of the potatoes. If the unsaturated compounds were ethylene, the concentration present was sufficient to cause appreciable retardation of sprouting.

In Appendix I, Part II, of this series (Callow, 1948) some of the sheep dissected by Dr Wallace were referred to as Suffolk x Border Cheviot Crosses. This should have been Suffolk × Border Leicester-Cheviot Crosses.

1. The changes in the sheep population and in the sales of fat sheep have been examined for the West Wales region for the period 1940–8. These changes consist of a gradual annual decline in sales, whilst the severity of the 1947 winter conditions brought about a rapid drop in both sales and population by nearly 33% from 1946 to 1947.

2. Analyses of sales of the four categories of fat sheep—rams, ewes, sheep and lambs—throughout the twenty-five collecting centres have been completed for the 4 years, 1943–6. These showed that lambs accounted for 85% of the fat sheep sales in this region.

3. It was found that the average estimated dressed carcass weight (e.d.w.) of the four categories of sheep (rams, ewes, sheep and lambs) declined gradually from the collecting centres of west Pembrokeshire to the inland centres on the eastern boundaries of the region. This cline is also found in the case of the summer suckling lamb, the autumn wether lamb and the winter-fed fat lamb.

Ghani's method for the partial fractionation of soil phosphorus has been simplified. From results obtained with soils and representative phosphatic minerals it has been shown that successive single extractions with 2·5% acetic acid-l% 8-hydroxyquinoline and 0·1 N-sodium hydroxide gives a good fractionation of the phosphate compounds present.

The relative effects of cupferron and 8-hydroxyquinoline as reagents for blocking the adsorption of phosphate were also investigated. Cupferron precipitated aluminium more completely than did 8-hydroxyquinoline at the pH used for the extraction. However, because of its instability and also because of indications that it may attack organic forms of phosphorus cupferron was considered to be of less value than 8-hydroxyquinoline in the fractionation of soil phosphorus.

The recovery of phosphate added to soil, the reaction of which had been varied by the use of sulphur or calcium carbonate, was almost complete at all reactions used (pH 4·5–8·2) for amounts of phosphate up to the equivalent of 500 parts of PO4 per million parts of soil. The distribution of this added phosphate between the acid and alkali soluble fraction showed that in acid soils the phosphate tended to be fixed mainly by adsorption or as a basic ferric and aluminium phosphates, while at an alkaline reaction most of the fixation was due to precipitation by calcium.

1. The myoglobin contents of selected muscles in horse, pig, domestic fowl and pigeon, and in the foetuses of horse, pig, sheep and cattle, have been determined.

2. The order of increasing concentration of myoglobin in the adult animal (4 years) is given by the series heart, longissimus dorsi, diaphragm and psoas, the figures for draught horse being, respectively, 0·325, 0·465, 0·610 and 0·705% and for pig, 0·203, 0·280, 0·350 and 0·435%, and the ratios of these concentrations being the same in each animal.

3. In both draught horse and pig, it is shown that the concentration of the pigment rises rapidly from birth, and that, after 2 years in the horse, and 1 year in the pig, it remains fairly constant, except in the case of horse psoas and diaphragm where there is a slow, but significant, rise throughout life.

4. This relationship of myoglobin with age has been shown to be significant at a probability level of 0·1%.

1. Sixteen colchicine treatments, involving five main methods of application and six concentrations, have been used on Triticum interspecific crosses, Triticum—Aegilops intergeneric crosses and Agropyron—Triticum intergeneric crosses.

2. The efficacy of the major treatments in terms of plant survival, plant fertility and ear fertility has been compared, and the most successful method of application has been found to be absorption through the cut leaves—i.e. capping cut-back tillers with a small glass phial containing colchicine.

3. Fertility induced by colchicine is not complete. In plants producing grain, every ear is not necessarily fertile, nor are all spikelets in fertile ears usually fertile.

4. Evidence has been obtained of differential cross response to colchicine action, and also of cross-group response to particular treatments.

1. Three experiments confirmed the view that losses, poor weight gains and low food consumption were always problems among pigs reared in an open pen in a large uninsulated building in comparison with the better results for pigs reared in wooden ark huts. Pigs in an ark hut with an outdoor run did better than those in one with an indoor run.

2. The effective temperature of the different types of housing was estimated. The differences found were not large but the environment which produced the best pigs had the highest effective temperature.

3. The provision of an insulated, dry floor to sleep on made it possible to rear good pigs in a pen where before they had failed. Woollen jackets did not provide sufficient insulation to affect the growth or health of pigs in a hut or pen.

Some aspects of intervarietal crossing in Lolium perenne have been studied.

Using a number of experimental designs with non-red plants as the tester variety, results have been obtained as to the effects of isolation distance on intervarietal crossing.

In all cases contamination decreases rapidly, at first with increasing distance, but there is a progressive reduction in the rate of decrease produced by repeated increases in isolation distance. The actual rate of decrease varies with the number and arrangement of plots.

The effect of intravarietal pollen in reducing intervarietal crossing appears similar to that of distance in its mode of action. Within short distances from the contaminant, additional rows of intervening plants are highly effective in reducing contamination. This suggests that pollination within a population of plants occurs chiefly between neighbouring plants.

The flowering periods of the different strains of Lolium perenne and L. italicum overlap to varying degrees. Several early strains flower at the same time, e.g. British commercial, New Zealand Certified Mother Seed and Station-bred S24 perennial rye-grass; others, such as Kentish indigenous perennial ryegrass and strains of L. italicum, which are intermediate in date of flowering, overlap with both the early- and late-flowering strains.

Intervarietal crossing is considerably reduced when varieties which differ widely in date- of flowering are grown in close proximity to one another, but even in the case of extreme early and late strains some spatial isolation, or discarding of border rows, is necessary for maintaining varietal purity.

In certain instances when seed crops of early-flowering strains are endangered by late-flowering plants growing in adjoining leys, satisfactory isolation may be achieved through cutting back the contaminant crop just before flowering. When seed crops of late-flowering strains are grown alongside leys containing early-contaminant varieties, cutting back should be delayed until a few days prior to commencement of flowering in the seed crop.

The practical application of the results to grass seed production has been discussed. Existent isolation requirements appear not too great for grass seed crops intended for further seed multiplication, but for commercial seed crops the spatial isolation distance generally recommended may be reduced to 100, or even 50 yd., in the case of large fields.

A study of residual phosphorus in soils resulting from the use of phosphate fertilizers has been made, using a simplification of Ghani's method for the fractionation of soil phosphorus.

In cultivated soils all the residual phosphorus was extractable by successive extractions with 2·5% acetic acid-1% 8-hydroxyquinoline and 0–1 N-sodium hydroxide, and practically all had remained in the inorganic form; very little, if any, change in organic phosphorus was recorded as a result of the application of superphosphate.

In pasture soils (uncultivated) the application of phosphatic fertilizers brought about an increase in both inorganic and organic phosphorus and, in addition, some of the applied phosphate may have entered a form not extractable by the two extractants. The increase in organic phosphorus was not directly proportional to the amount of phosphate applied, as were the increases in the extractable inorganic fractions. It tended to approach a constant value, irrespective of amount and nature of the phosphate applied.

A simplification of Ghani's method for the fractionation of soil phosphorus has been used to study relationships between soil and plant phosphorus in field and pot-culture experiments.

In pot-culture experiments with red-brown earth soils (pH 5·6–6·1) wheat derived approximately 60% of its phosphorus from the fraction of soil phosphorus soluble in 2·5% acetic acid-1% 8-hydroxyquinoline and 30% from the inorganic fraction soluble in 0·1 n-sodium hydroxide, even although the amount of acetic acid soluble phosphorus present in these soils was only about half that present as inorganic alkali soluble. Very little use was made of organic phosphorus.

In field experiments with similar soils there was a correlation between the percentage phosphorus in the plant material and the acetic acid soluble, the inorganic alkali soluble, and the sura of these two fractions of soil phosphorus. The sum of these two fractions was also correlated with the amount of phosphorus taken up by the crop.

In pot-culture experiments with a wider range of soil types there was good correlation between the total extractable inorganic soil phosphorus and both the phosphorus content of the plant and the phosphorus uptake. Correlations between individual inorganic extractable soil phosphorus fractions and plant phosphorus were influenced by the pH of the two groups of soils examined.

The analysis of simple change-over trials based on Latin squares is considered. It is shown that several difficulties are encountered when estimates of residual effects are required. In particular, there may be biased error variances.

In certain circumstances the amount of bias in the error variance can be estimated in a proportion of the experiments based on a given design. If this bias is sufficiently large to be of importance an average correction can be calculated for use with further experiments of the same type.

1. There was no evidence that the higher body temperature of the chick, compared with other animals, conferred any advantage on it in the digestion of high melting-point fats, as exemplified by mutton fat.

2. The digestibility of linseed oil ranged from 95·0 to 99·9%. The highest digestibility observed for mutton fat was 88·1%.

3. The capacity to digest considerable quantities of linseed oil was rapidly developed in the chick. Adaptation to digest mutton fat was much slower.

The problems arising in the analysis of changeover trials based on complete Latin squares have been independently investigated by Dr H. L. Lucas, of the Institute of Statistics, University of North Carolina, who is preparing a book on the subject of animal experimentation. Dr Lucas has obtained similar results to those presented in this paper. He has also conducted a more extensive investigation of the magnitude of the bias in the error variance, and has come to the conclusion that in experiments on dairy cows it is not of sufficient magnitude to be of practical importance. These results will shortly be published.

During 1947–9, field and pot experiments have been carried out first to assess the herbicidal properties of 2:4-dinitro-6-secondary-butyl-phenol, and secondly to determine its value for selective weed control in leguminous crops. In order to obtain precise estimates of the concentration required to produce a given percentage mortality of either weed or crops species, such experiments were so designed that the results are capable of probit analysis.

From the data of field experiments on thirteen species of annual weeds, it is evident that there are wide variations in the concentration required to produce a standard kill. Irrespective of the species, susceptibility is greatest in the young seedling stage and there is a rapid increase in resistance with age. For example, with Raphanus raphanistrum between the cotyledon and pre-flowering stage a sixfold increase in concentration is needed to give a 90% mortality.

1. Herring ‘alkali-reduction’ meal—a by-product from the alkali process of herring oil extraction—has been tested as a protein supplement for chicks.

2. At high levels of feeding it was toxic.

3. At low levels of feeding its nutritive value was low compared with other fish meals.

4. The method of manufacture of reduction meal destroys vitamin B12 and cystine, but supplementation of the material with vitamin B12 and cystine did not greatly enhance its feeding value.

1. An experiment was carried out from 3 May to 10 October 1949 to compare close-folding with rotational grazing of dairy cows. With close-folding the cows were moved daily to an area of fresh pasture which was calculated to supply the day's feed requirements; the rate of stocking ranged from 50 to 80 cows per acre. With rotational grazing the cows were stocked on pasture at the rate of 6–8 cows per acre and moved from one pasture to another at intervals of 5–14 days. Two uniform groups of Ayrshire cows were used, and each group spent a period on each system of grazing. Two pastures, a ryegrass-dominant old pasture and a cocksfoot-dominant ley, were used, and as far as possible the pasture grazed by both groups of cows was similar. Nitrogenous top dressings up to 104 Ib. nitrogen per acre in the season were applied uniformly to both the close-folding and rotational areas. No supplementary feeding was given to the cows.

2. The best methods of close-folding practised gave 215 and 201 cow-days of grazing per acre with 550 gal. milk per acre from the cocksfoot ley and 582 gal. from the permanent pasture. Rotational grazing on the same two pastures gave 181 and 138 cow-days and 450 and 351 gal. milk per acre respectively.

1. The relationship between the soluble nitrogen content (soluble nitrogen/total nitrogen) of samples of dried silage and the pH of the corresponding wet samples has been investigated. It has been shown that a relationship exists between the two, and that when Ns/Nd is high the pH is low and vice versa. Moreover, the product Ns/Nd × d.m. is also related to the pH.

2. Again it has been shown that the ratio Ns/Nd bears a relationship to the digestibility of the silage as measured by the Wedemeyer Method in the laboratory. The potential usefulness of the ratio in this connexion is being further investigated.