In the investigation described, we have observed a t monthly intervals throughout gestation the changes taking place in a series of similar ewes, in lamb to the same ram, and each receiving the same standard diet.

In following the live-weight growth curves of the ewes it was found that on a constant level of feeding the weight gains became greater during each succeeding month of pregnancy, and at corresponding stages were larger for ditocous than for monotocous ewes. This was found to be due to the fact that, although on our diet the ewes did gain slightly in actual body weight, the main increases in live weight resulted from the growth of the gravid uterus itself, and this increases in weight far more rapidly in the later stages of gestation, and is also heavier where twins are carried.

By measurement of single fibres from tattooed squares the variation in hip region mean cross-sectional area, mean fibre length and area of skin covered by fibre substance in a small flock of Romney sheep has been studied for a few years—see Part I.

We find that under good growing conditions the area of skin covered by fibre is a constant percentage of the skin area for all sheep in all years. The number of fibres per unit area varies from sheep to sheep, and the mean cross-sectional area is inversely proportional to the number of fibres per unit area. The mean length/day is a constant for all sheep. When conditions are unfavourable the percentage of the skin area covered by fibre on a particular sheep falls below the good growing conditions percentage by an amount that is smaller the bigger the skin expansion ratio, but is greater the worse the season.

1. Pot and field experiments were made to compare the effects of thiosulphates and sulphur on the incidence of manganese deficiency in oat, beet and pea grown in two manganese-deficient soils.

2. The addition of sodium or calcium thiosulphate to oat plants growing in a manganese-deficient fen soil in boxes markedly reduced symptoms of ‘grey speck’ and increased the soluble manganese content in the leaf tissues, but the effect was transient.

3. The growth of beet in this soil in clay pots was improved by the addition of thiosulphates, and also by painting the exterior of the pots with bitumen paint or by covering the surface of the soil with a thin layer of sand. The thiosulphate treatments increased the manganese uptake by the plants and reduced the symptoms of manganese deficiency, particularly when applied to pots painted with bitumen paint.

4. Field experiments with an old garden soil deficient in manganese showed that thiosulphate treatments increased the manganese uptake of beet. Placement treatments were more effective than broadcast treatments and greatly improved the growth of beet and reduced or eliminated manganese-deficiency symptoms, without producing any change in soil pH.

1. A method is described whereby fructose content and fructolysis can be assayed accurately in small samples of semen. The advantages of this method lie in its simplicity, accuracy and practical convenience as a tool for the assessment of semen quality, applicable also under field conditions.

2. The content of fructose in fresh semen depends upon the secretory function of accessory glands which is influenced directly by the activity of the male sex hormone. A low level of seminal fructose may coincide with other symptoms of hormonal malfunction and poor quality of spermatozoa. A high level of seminal fructose indicates satisfactory functional ability of the accessory glands, but it does not necessarily coincide with high quality of spermatozoa as expressed in terms of density and motility.

3. The normal level of fructose in fresh semen undergoes frequent fluctuations which can be observed if semen collections are made from the same individual at different times. Considerable variations in the sperm/fructose ratio may also occur in the semen of the same individual as illustrated by the results of an ‘exhaustion test’.

4. Fructose disappears from semen incubated in vitro. The rate of fructose disappearance forms a convenient measure of sperm fructolysis. The normal rate of fructolysis in bull semen is 1·4–2 mg. fructose per 109 sperm cells in 1 hr. at 37° C. At this high level it can be maintained until almost the whole reserve of fructose has been exhausted. Azoospermic and necrospennic semen, as well as that from vasectomized animals, are unable to utilize fructose. A reduced rate of fructolysis is found in low quality semen of subfertile and infertile animals.

5. The conditions of sperm survival in semen incubated in narrow tubes as used for the fructolysis test as well as for storage of semen in the practice of artificial insemination, are almost purely anaerobic. Under such conditions the survival of spermatozoa must largely depend upon fructolysis and not upon respiration.

1. Picton, a winter-hardy variety of oats selected from the cross Argentine x Grey Winter, contains plants which have irregular meiotic divisions.

2. Two types of irregularities were observed: first, univalents and the products of their division; and secondly, bridges and fragments at both first and second divisions.

3. Plants selected for a low frequency of irregularities produced offspring with a low frequency of irregular divisions. On the other hand, plants with regular divisions were also obtained from parents which had a high frequency of irregularities.

4. It is pointed out that the genetical effects of bridge chromatid formation and breakage is the production of gametes deficient for chromosome segments. There is some evidence that chlorotic plants are produced when such deficiencies become homozygous.

5. It is suggested that the meiotic irregularities produce a certain degree of heterozygosity which may make Picton more adaptable, and at the same time give it a certain degree of hybrid vigour.

When maize forms a large part of the diet of any group of people, pellagra can be prevented by increasing the amount of nicotinic acid or by increasing the amount of tryptophane in the diet. The possibility of increasing the nicotinic acid content of maize by genetical means presents a promising field.

1. Some data are given for the relative buffer-index values of saps from underground parts of wheat, barley, oats, potatoes and turnips.

2. The correlation of these values with limits of tolerances of soil-pHranges by the plants is discussed.

3. Some possible practical applications for these data are indicated.

Ten fully grown Border Leicester-Cheviot ewes were divided into two groups of five; the heavier ones being about 150 lb. live weight, and the lighter ones about 70 lb. The former were placed on a low plane of nutrition, and the latter on a high plane. As the weights changed by successive amounts of 20 lb. animals were killed and dissected, and their organs and tissues weighed.

The metabolism trials described in the present communication were undertaken with the object of testing the conclusions arrived at in farm-scale feeding trials, designed in accordance with the requirements of the modern statistical lay-out, respecting the minimum protein supply needed to support the maximum rate of growth in bacon pigs.