1. Crops sensitive to manganese deficiency are generally healthy on soils with more than 0·3 mg. exchangeable Mn%, but they may also be healthy on soils with less than this amount.

2. Other fractions of the soil manganese, including those which are either readily reducible or soluble in sodium hexametaphosphate, are no more successful than the exchangeable manganese in characterizing deficient soils.

Field experiments were carried out to measure the effect on the yield and composition of sugar beet of infection with beet yellows virus, and to determine how the effect varies with rate and date of infection and with date of sowing and harvesting of the crop.

Control measures designed to prevent spread of infection within experimentally infected plots and introduction of infection from sources outside the experiment, were not completely effective. Consequently the numbers of plants which became infected differed from those prescribed by the experimental treatments. The effects of infection were, therefore, estimated by means of regressions on the numbers of plants observed to become infected on successive dates.

After correcting the observed yields for accidental infections by means of the regression coefficients, it was found that the effect of infection on the yield of sugar was linearly related to the rate of infection, i.e. the loss of yield of sugar caused by infection was proportional to the percentage of infected plants. There was no compensation for loss in infected plants by increased growth of healthy neighbours.

The effect of infection on yield of sugar decreased linearly with later date of infection, falling to values not significantly different from zero at the date of harvest. The loss of yield caused by infection was therefore approximately proportional to the interval of time between the date of infection, as shown by the appearance of symptoms, and the date of harvest.

The carotene content of Palestinian fodder plants, vegetables and wild plants was determined. The examined fodder plants were: Egyptian clover, Fahli clover, lucerne, horse beans, field peas, vetch, oats, barley, cow peas, maize, pencillaria, Sudan grass and leaves of beetroots. The examined vegetables were: leaves of radish, mangold, sweet potato, spinach, cauliflower, parsley, lettuce, kohlrabi, onion and cabbage. The wild plants examined were: nettle, mallow and portulaca.

Much work has been done with regard to the elements necessary for plants, their function in the plant, methods of absorption, amounts necessary, nutrient solutions, etc. The following is particularly, concerned with nutrient solutions, including their composition, concentration, methods of application, and the general methods of dealing with sand and water cultures. The work is confined mainly to a study of the major elements.

1. A fraction of soil manganese soluble in buffered pyrophosphate solutions has been identified as three-valent manganese, present in the extract as a soluble complex salt of mangani-pyrophosphoric acid H[MnP3O7].

2. Evidence is given to show that a very significant part of soil manganese may be present as three-valent manganese, and that the product of oxidation of divalent manganese in soils is three-valent manganese. In any soil where the production of divalent manganese by reducing processes is going on at any appreciable rate, the oxidation of divalent manganese will supply three-valent manganese, which may therefore be expected to form a relatively large part of the manganese of certain soils.

A suitable method of fluorimetric determination of riboflavin was developed, and riboflavin in various poultry feeding stuffs was determined by its use.

Riboflavin was determined in fodder plants, vegetable refuse and wild plants. The influence of seasonal changes and of different stages of growth on the riboflavin content in fodder plants was investigated. Summer-grown plants contain more riboflavin than those grown in the rainy winter season. The riboflavin content of the plants declines in the course of their growth.

1. The effect of low-temperature and continuous-light treatment of seedlings of certain sugar beet strains in the isolation of distinct physiological types is described. The progenies of individual plants and bulk samples of different anthesis dates show some difference in the proportions of early and late plants, when these progenies are similarly exposed to low temperatures and continuous light in the seedling.

2. Different treatments of progenies in relation to light treatment in the seedling stage result in distinct behaviour with regard to anthesis date and the number of plants reaching the stage of anthesis.

3. The comparative resistance to bolting from a field sowing of seed obtained from plants which ripened seed after continuous light treatment of the seedlings is noted. This was so in spite of the fact that only 66% of the plants had reached anthesis as a result of the treatment, and the seed was obtained from the most rapidly bolting plants.

4. Light and low temperature exposure of seedlings is effective in two different strains for isolating bolting-resistant types as measured directly from the seed of these bolting-resistant plants and selected progenies from these plants. Differences in the field germination and establishment from very early sowings were discernible in the progenies.

Statistical experiments have been carried out as pot cultures in the greenhouse, with sand and soil as the aggregates (nutrients being supplied to both aggregates in the form of nutrient solutions), on the growth of the two vegetables turnip and spring cabbage to the stage of maturity usual in actual practice. With full nutrients, the soil, possibly because of such factors as its nutrient reserves, its physical properties, and its capacity for retaining certain nutritional elements supplied, was superior to the sand as judged by yields of fresh and dry matter for tops and whole plants of both vegetables, and roots for the turnip, thus including the edible portion ofboth plants; the (true) root of the cabbage, however, yielded more in the sand under these conditions. Similar results were obtained even when the concentrations of the nutrients for the soil were only half those in the full nutrient solution applied to the sand, so that it may be stated that fresh soil is greatly superior to sand under equal conditions as an aggregate in the growth of vegetables with nutrient solutions.

A continuous cattle census scheme was started in the Central Province of Nyasaland in 1943, and data thus accumulated on the calving rate of native cattle form the basis of this paper.

The system of animal management prevailing in the area is described, and meteorological data collected at Lilongwe over 3 years are also given.

Experiments are described in which the ‘once-used’ soils left over from previous culture experiments were employed as aggregates in the growth of vegetables. It was demonstrated that sand with full nutrients was superior to ‘once-used’ soil with water only, but that ‘once-used’ soil supplied with the full quota of soluble nitrogen was superior to the sand with full nutrients. The root of the cabbage in sand was an exception, and a possible explanation was that sand as aggregate favoured true root formation, while soil favoured the formation of tops. The ‘once-used’ soil in these experiments deteriorated in physical propertes owing to the conditions of the experiment, which included the use of nitrogen as sodium nitrate, possibly owing to the tendency to the formation of sodium clay; it is argued that a judicious choice of fertilizers and/or the use of flocculating electrolytes should overcome such tendencies.

When a factorial experiment involves many factors each of which is tested at two levels, economy of space and material may be effected by using only a fraction of a complete replicate of all possible combinations of levels of the factors. The consequence is that each main effect and each interaction has one or more aliases, and the experiment cannot distinguish which member of a set of aliases is responsible for an observed difference in yields. For less than five factors, this feature prevents fractional replicate designs from being much use; for five or more factors, the fraction can be so chosen that main effects and two-factor interactions have only higher order interactions as their aliases, and the possibility that these are important may often be ignored. Within the fraction of a replicate chosen for an experiment, confounding of interactions may be introduced in order to reduce the block size.

Designs likely to be useful in field experiments are those for six factors in four blocks of eight, for seven factors in eight blocks of eight, and for eight factors in eight blocks of sixteen or in sixteen blocks of eight; in the first of these a two-factor interaction is amongst those confounded, but elsewhere all main effects and two-factor interactions are unconfounded. The method of construction of the blocks, for these designs and those involving more factors, has been described, and an example of the statistical analysis of experimental results (which presents no special difficulties) has been given.

The nutrition of the carrot in a light gravel soil of known analysis with high available phosphate has been studied by statistical pot-culture methods, and the responses, linear and curvature components, etc., due to nitrogen, phosphate, and potash, have been calculated.

No hard and fast rule can be made as to the adequacy or otherwise of any particular fertilizer in a soil, as the different parts of the plant (top and root) were shown to be capable of responding quite differently to that fertilizer.

1. With the object of determining the vitamin A value of carotene in different green fodders, an investigation has been undertaken to study (i) the relation between the chemically determined carotene and its biological activity as compared with that of standard carotene, (ii) the purity of apparent carotene from different sources, (iii) absorption of carotene in rats, and (iv) the relative efficiency of the standard carotene and preformed vitamin A.

2. Biological tests have shown that the chemical method of assay is a fair index of the true carotene content in green fodders, and carotene in the form of an extract is quite as effective in the system as that present in the plant tissues. β-Carotene appears to be predominant in these materials.

1. Clover sickness caused by Sclerotinia Trifoliorum is widely distributed in the American continent and western Europe; and in Britain it is often of considerable importance, especially in parts of East Anglia and Yorkshire. The severity of the disease is dependent upon the season, and in some countries very severe financial loss may result.

2. Most of the commonly grown legumes are subject to the disease, but they vary in their susceptibility. Peas affected with the disease have not been observed in the field although they succumb to artificial inoculation.

There was a significant positive correlation between the buffer capacity and motility of sperm and a highly significant negative correlation between the buffer capacity and the pH. There was no correlation between the buffer capacity and the volume of the ejaculate or the number of sperm per c.mm. Specimens which maintained a good motility on storage had a better buffer capacity than those which did not.

The specific gravity of 125 semen specimens was 1·0337. There was a highly significant positive correlation between the specific gravity and the number of sperm per c.mm. and the percentage motility and a highly significant negative correlation between the specific gravity and the pH. There was no relationship between the specific gravity of semen and the volume of the ejaculate, or the pH change. In general, the higher the specific gravity of the seminal fluid, the better was motility maintained on storage. The higher the specific gravity, the lower was the pH and the better the buffer capacity of seminal fluid.

1. 238 samples of carrots comprising over seventy varieties were analysed for total carotenoids (t.c.) during five autumns.

2. The average t.c. value for common types (excluding certain very high value varieties and the almost colourless varieties) is 13·8 mg./100 g. fresh carrot. Assuming 90% of the carotenoids to be ‘carotene’ the average for the latter is 12·4 mg./100 g. Negligible correlation is found between named variety and t.c. Red-cored and small-cored varieties are slightly richer than others. The pedigree of the seed is the most reliable indicator of probable t.c. content.

3. Six high t.c. varieties and a Red-Cored Chantenay are described in detail. Four of them are of the long slim type with small red cores. One of them (Dippe's Surrey Long) has a mean t.c. value of 37·1 mg./100 g. The high values have been further improved by selection in two subsequent generations.

The authors thank Drs L. J. Harris and T. Moore for their interest in this work, and Miss D. Bailey, Messrs A. G. Dockrill and K. R. Symonds for technical assistance.

1. An experiment was performed to compare some methods of supplying calcium to intensively kept chickens.

2. The calcium content of a mash was adjusted to contain low (0·13%), normal (1·16%) and high (2·14%) amounts, and each of these mashes was fed to groups of chicks having access to: (a) no grit, (b) flint grit alone, (c) limestone grit alone, (d) both flint and limestone grit.

3. The addition of flint grit significantly improved the efficiency of food utilization on all diets, whether limestone grit was provided or not.

4. On all three mashes the total amount of calcium grit consumed was greater in the presence of flint grit than when it was fed alone.

5. As the level of calcium in the diet increased, the amount of limestone grit consumed decreased, whether it was fed alone or in the presence of flint grit.

6. The best results, judged on a live-weight basis, were obtained when the normal calcium mash was fed with flint grit alone, followed by the low calcium mash with both flint and limestone grit, followed by the normal calcium mash with no grit.

7. On the basis of the efficiency of food utilization, the low calcium diet with flint and limestone grit was best followed by the normal calcium diet with flint grit alone.

8. Access to limestone grit reduced the efficiency of food utilization in all but the low calcium diet.

Repeated attempts have been made, both during the recent war and the war of 1914–18, to make the store of starch and other nutrients in the horse-chestnut available for farm animals. Unfortunately, the extremely bitter taste of the horse-chestnut, due to the presence of saponins and, to a smaller extent, of tannins, has proved a severe obstacle, and horse-chestnuts have been found to be an unsuitable food for livestock both on account of their unpalatable character and their constipating action.

The mean sugar content of bull semen was 470±11·7 mg. %. There was no relationship between the sugar content and the volume of the ejaculate, the number of sperm per c.mm., the initial motility and the maintenance of high motility during storage.

The mean percentage reduction in sugar after 24 hr. for undiluted semen stored at 10° C. was 23·85 ·1±76%. There was a significant positive correlation between the sugar reduction and initial motility, and a highly significant positive correlation between sugar reduction and the concentration of sperm. The negative correlation between reduction in sugar and the period for which good motility was retained on storage was not significant.

In the breeding of animals like cattle which reproduce slowly relative to the working life of a breeder, time is a factor of major importance. A study has therefore been made of the duration of samples of pedigree herds in order to obtain some indication of the time actually spent by breeders in the selective breeding of dairy cattle.

The samples consisted of pedigree Ayrshire, Jersey and Shorthorn herds, (a) established at various fixed times in the past; and (b) existing in 1939. The former were traced forwards, and the latter backwards, by means of herdbook registrations. Each sample contained not less than 300 herds, and the distribution of durations in each was considered in relation to the movement of population numbers in the whole breeds from which they were drawn.