In the investigation described in this third part of the work, we have studied the effect of imposing two extreme levels of diet upon the pregnant ewe during two periods, one of early and one of late, gestation. In order to build up a comprehensive picture of the effect of these treatments we have been concerned, first, with the changes that they have wrought in the tissues and organs of the mother's body; secondly, with the effect upon the growth and development of the genital tract and its major components, and lastly with the way in which the growth of the tissues and organs of the foetus have responded to the different nutritive levels. While the latter has been our primary concern, the former have been studied in some detail so that we may view the effects produced as a whole, and gain an understanding of any competition that may have occurred between maternal and foetal tissues.

1. Metabolism experiments have been made with five sheep fed iodinated casein in doses sufficient to give symptoms of hyperthyroidism, ranging from moderate to severe. Two comparable sheep were included to serve as controls.

2. The same ration was used throughout each experiment, and it was found that the digestibility of its dry matter and of its crude protein content declined when the sheep were made hyperthyroid. This was due to increased peristalsis.

3. The treated sheep lost body N when iodinated casein was given, the loss being proportional to dosage. Calculations indicated increases in the endogenous catabolism by up to 120%, and also increases in deamination.

4. There was an increased excretion of urea and ammonia during hyperthyroidism, the latter being associated with a decrease in the plasma carbon dioxide combining capacity.

5. Purine catabolism was accelerated by more than 50% in some sheep. Starvation of one sheep did not depress nucleoprotein catabolism as it does in the normal sheep.

In presenting the results of these investigations, we have attempted to discuss in each section the findings that have been described, and here we will merely be concerned with summarizing the major points that have emerged.

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.

The changing of treatments during the course of an experiment is discussed both from the point of view of designing trials in which changes are anticipated and of modifying trials that have fulfilled their original purpose. Cases are distinguished according to whether the interactions of original and new treatments are or are not important and recommendations are made for each case.

We are indebted to Miss J. M. S. Thom for preparing the diagrams fot publication.

1. The results of a study of sampling for ginning percentage in cotton variety trials are given. The investigation was undertaken to determine the most satisfactory method of obtaining the necessary ginning percentage factors for conversion of yield of seed-cotton to yield of lint.

2. The material consisted of a widerange of strains derived from the jassid-resistant Upland, U4, planted out in trials of randomized block design, in different seasons.

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. The physiological effects of severe hyperthyroidism on five sheep are described.

2. Increases in pulse rate of more than 100% were observed. The increase in pulse rate was proportional to dosage with the exception of one sheep which had lesions on the chordae tendinae of the left ventricle.

3. The heart, even though beating at this elevated rate, reacted normally to severe exercise, but there was a tendency for the sheep to carry out its normal functions at a slower rate so such large increases in pulse rate did not occur as the result of voluntary activity.

4. Considerable cardiac arrhythmia was noticed in all hyperthyroid sheep.

5. The relative increases in pulse rate of the cow and the sheep given iodinated casein of the same potency suggest that as between species dosage of iodinated casein is proportional to ‘metabolic body size’—the between species unit of basal metabolism—rather than to body weight itself. On this basis the stimulation of the sheep was between 1 and 4 times the dosage accepted as normal for the cow.

6. Body temperatures increased in the most severely affected animals. Respiratory rates quadrupled in some cases.

1. A study of different methods of staple-length measurement of material from a cotton variety trial, of the comparative accuracy of three persons' measurements and of the number of seeds which it is necessary to measure in order to achieve various degrees of accuracy in the determination of differences in variety trial and single plant material is described.

2. If, in making single plant selections, the breeder is satisfied with a level of significance of P =0·1 when using a sample of only five seeds per plant, he would be justified in discarding material falling one and a half millimetres below the standard of staple-length at which he was aiming.

1. The ventilation of two byres, one of large (1248 cu.ft.) and one of small (567 cu.ft.) cubic capacity per cow, was studied. The CO2 concentration in the atmosphere was used as a measure of the rate of air change and the dry katathermometer to determine the cooling power of the atmosphere. Temperatures and relative humidities were recorded and the actual air movements were studied by using smoke trails. The investigations were made under a variety of weather conditions and with a wide range of outlet and inlet areas.

2. It was shown that the atmospheric conditions in the large byre were almost always superior to those in the small byre, and this was undoubtedly due to the greater cubic space per cow in the large byre. Adequate ventilation was, however, readily attained in the small byre provided the outlet area was sufficiently large.

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. The compositions and digestibilities of ten selected typical Northern Irish meadow hays have been ascertained and compared with similar data published by other workers for meadow hays produced in the British Isles.

2. It is suggested that average Northern Irish meadow hay of reasonably good quality has a starch equivalent value in the region of 35 on a drymatter basis. Poor samples will have a value in the region of 25.

Comparative digestibility trials have been carried out on hays top-dressed with nitrogenous fertilizers 8–13 days before cutting and on similar hays which were not top-dressed.

The top-dressing resulted in an increase of 2·0% crude protein and 1·2% true protein.

The digestibility of the protein was significantly higher in the top-dressed hays and no other constituents were affected.

The protein equivalents in hay dry matter were increased from 4·4 to 6·0% by the top-dressing.

1. In a ration containing paddy straw, the large amount of oxalate ingested does not act in the same way in the ruminant system as has been observed when oxalate-rich spinach is fed to rats. About 10 % of the ingested oxalic acid is recovered in the faeces, and this can be explained as arising out of pre-formed insoluble and unabsorbable calcium oxalate present in paddy straw; the remaining 90%, which is soluble potassium oxalate, does not react with the calcium of the Tation to form unabsorbable calcium oxalate.

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. The importance of uniform production of herbage for crop-drying is emphasized.

2. A replicated experiment is described which compared four crops, two annuals and two leys under four manurial treatments which included a control and three applications of fertilizer (3½ cwt. ‘nitrochalk’) distributed during the season in three ways.

3. Vetches yielded 2500–3000 lb. dry matter per acre of 28–30% crude-protein content in two cuts.

Barley yielded 2500–3000 lb. dry matter per acre of 18–21% crude protein in five to six cuts.

Leys yielded 4000–5000 lb. dry matter per acre of 15–18% crude protein in four cuts in their first year, and 5000–6000 lb. dry matter per acre of 15–18% crude protein in five cuts in their second year.

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.

An experiment using eight pens each of twenty-five pullets was conducted to investigate the suitability of sesame cake meal as a protein concentrate for laying pullets. In meal mixtures supplying equal amounts of crude protein, sesame cake meal gave slightly lower production than fish meal and earthnut cake meal, but the differences were of doubtful statistical significance. Body weights appeared to be maintained less well on sesame cake meal, but only by an unimportant amount.

The authors thank Prof. R. G. Baskett for his advice and constructive criticism, and Miss M. E. Osborne for the care and attention devoted to the management of the pullets.

1. The weights of muscular tissue, fatty tissue, bone, and tendons, etc. in the carcasses of twenty-nine cattle, fifty-five sheep and forty pigs are given. The weights of fat, dry fat-free residue, and water in the muscular and fatty tissues from the carcasses of twenty-nine cattle, twenty-nine sheep and two pigs (one wild and one domesticated) are also given. The cattle represent eight breeds, the sheep nine breeds and the pigs two breeds. Ages range from newly born to over 12 years and there are fifty females, seventy castrated males and four newly born males. The animals thus represent a very wide cross-section of the meat industry.

The available data on calcium, phosphorus and carbonate balance experiments with laying and non-laying birds have been collected and condensed. From this condensed data the following relationships have been derived:

(1) Calcium excretion is a function of calcium intake.

(2) Phosphorus excretion is a function of phosphorus intake.

(3) Carbonate excretion is a function of carbonate intake.

(4) Carbonate/calcium ratio of the excreta is a function of carbonate/calcium ratio of the intake.

(5) Calcium/phosphorus ratio of the excreta is a function of calcium/phosphorus ratio of the intake.