1. Increasing the ballast on pneumatic tyres, up to a certain weight, improves the tractor performance as judged by its speed, fuel consumption and wheel slip. Further increases beyond this point continued to decrease the wheel slip without having any marked effect on its speed or fuel consumption. No certain evidence was obtained that too heavy a ballast decreased the tractor's efficiency.

2. The tyre load affects the maximum pull the tractor can exert while working reasonably efficiently, but this pull does not depend markedly on the speed of work. Wheel weights of about 12–13 cwt. seem to be the minimum required for optimum performance of the 36 or 28 in. tyres at pulls of 1800 lb. under fairly good ground conditions, and possibly a greater weight may be required by the 24 in. tyre.

3. If the tractor is ploughing it is usually running tilted, and this tilt transfers sufficient weight on to the furrow wheel for it to work efficiently under most conditions. Additional ballast is, however, often necessary for the lighter land-side wheel.

4. Tyre performance is much less dependent on inflation pressure than on ballast. Pressures below 10 lb./sq. in. were only of use in wet conditions when small amounts of additional ballast were not available. Pressures above 12 lb./sq. in. may allow excessive slip to take place and probably only need be used on the furrow wheel of a well-loaded tractor ploughing.

1. A series of balance experiments to compare calcium carbonate, calcium sulphate and calcium gluconate as sources of calcium for laying hens is described.

2. Not one of the three supplements showed all-round superiority, but calcium sulphate was the worst.

3. The main results indicate that:

(a) Calcium sulphate and gluconate cause scouring but carbonate does not.

(b) The best retention of calcium occurs with gluconate and the worst with sulphate.

(c) Calcium carbonate gives the best shells and calcium sulphate the worst.

4. The experiments also throw fresh light on some more general aspects of calcium and phosphorus metabolism.

5. On the basis of these general results and a review of the literature of blood calcium and phosphorus in laying hens a theory dealing with certain aspects of egg-shell formation is presented.

1. The question of the maintenance requirement of calcium for poultry is discussed.

2. On the basis of curves relating intake of calcium to calcium in the droppings, a maintenance value for laying and non-laying birds is estimated.

3. It is suggested that in the case of both laying and non-laying birds the maintenance requirement of calcium is about 0·10 g. and that the endogenous calcium value is about 0·05 g.

1. An individual feeding experiment using forty-eight pigs and a group feeding experiment using twenty-nine pigs have been carried out with the object of testing the so-called Lehmann system of pig feeding, where the amount of meal allowed for the fattening pig is restricted to a basal ration of 2½ lb. each and farm bulky foods or food wastes fed ad lib. used as supplementary foods.

2. Using a mixture of 6 parts mangold and 1 part biscuit waste as a supplementary food, live-weight gains only slightly less than with all-meal feeding have been obtained and a great saving in meal consumption effected. Under more favourable conditions as much as 1¾ lb. of meal has been saved for each 1 lb. live-weight gain.

An account has been given of recent work on the chemical nature of war-time swill and on the best methods of using this product so as to ensure the maximum replacement of concentrates, consistent with economical live-weight gains, in the rations of bacon pigs.

Three different types of swill have been submitted to investigation: (1) a meat-rich military camp swill, characteristic of the material available during the first 18 months of the war; (2) processed urban swill, commonly known as concentrated swill; and (3) dried, balanced swill. In addition, the results of an investigation into the variation in composition of household and restaurant swill are also given.

The different types of swill have been examined from the standpoints of (1) main ingredients, (2) chemical composition, both organic and mineral, (3) digestibility, when fed to bacon pigs, and (4) nutritive value in comparison with mixtures of common pig foods. The keeping qualities of processed urban swill and dried, balanced swill have also been investigated, and attention has been devoted to the problem of the seasonal variations of urban swill in respect of main ingredients, chemical composition and feeding value.

1. With insemination of approximately 2 billion sperms, pregnancy resulted from inseminations up to 6 days prior to ovulation, but not when inseminations were made earlier, or on the day after ovulation.

2. Ovulation was induced in one mare by injecting pregnancy urine extract when a large follicle was present in one ovary, although the mare remained anoestrous, as judged by vaginal and cervical secretions. This mare became pregnant from an insemination 2 days prior to the induced ovulation.

1. Growing young sugar-beet plants under continuous illumination before transplanting into the field induced stem elongation and anthesis in considerably greater proportions than in plants not exposed to continuous light exposure.

2. The technique of growing young plants under continuous light exposure during the winter offers a means of rapid multiplication of small seed stocks, and also of isolating the various physiological types comprising the population. In particular, the technique should make it possible to select types resistant to bolting.

3. Analysis of the glomerule populations obtained from the plants showing anthesis at definite dates indicates that there is a definite trend in the proportions of large, medium and small glomerules as the season progresses.