1. The accurate measurement of the amount of bone, muscle and fat in the bodies of meat animals is of considerable importance in all technical studies relating to carcass quality. Chemical analysis and laboratory dissection of complete animals are associated with disadvantages which preclude their extensive use. Material derived from nutritional experiments has provided the opportunity for statistical investigation of the possibility of using sample joints and carcass measurements as indices of the composition of bacon pigs of 200 lb. live weight. The extent and nature of the variation in the composition of the pigs concerned adds to the significance of the results obtained.

2. The total weight of bone, muscle and fat in the bacon-pig carcass can be estimated with a high degree of accuracy from the respective weights of these tissues in either the loin or the leg. The combination of these two joints provide even higher correlations in each case than either one alone. In all cases the correlation coefficients approach unity and are strongly significant at the 1% point. For the combined joints the values of r for bone, muscle and fat respectively are +0·9444, + 0·9765 and +0·9750. Regression functions have been developed for the purpose of estimating carcass composition from these joints.

Five inbred Large Whites from the same strain as used by McMeekan (1940) were reared on a High Plane of nutrition to approximately 330 lb. live weight at which one was killed as a control. The rest were put on to a submaintenance diet of straw and water and killed successively at roughly equal intervals in live weight between 330 and 200 lb. The weights of blood, organs and offals were determined and the carcasses were jointed and completely dissected into their constituent tissues. The total weights of each and the weights within the various joints were recorded.

(1) Organs. The early-maturing organs, brain, eyes, etc., continued to grow. Other organs like the heart, liver, lungs, etc., suffered a greater or less degree of atrophy which was probably determined by a suspension of their functions.

(2) Carcass composition. The tissues of the carcass were affected in reverse order to their development, i.e. fat most, muscle less and bone least. Bone continued to grow in the earlier stages of submaintenance.

1. Study of the automatic records shows:

(a) There is a seasonal change in the drainage response after rain which can be almost wholly ascribed to viscosity changes arising from seasonal changes of soil temperature (p. 77).

(b) Evaporation occurring after a fall of rain has no measurable effect on the drainage response to that rain (pp. 78, 87).

(c) The maximum drainage rates for the 20 in. gauge are much larger than those for the deeper gauges. The maxima change seasonally and are again primarily dependent on viscosity (p. 78).

(d) There is no marked change in the field capacity of the gauge during the year. The air-filled pore space at field capacity may change by about 15% of its average value (p. 81).

Natural drainage periods, i.e. periods between consecutive cessations of flow of the Rothamsted 20 in. drain gauge, were selected for the months of June, July and August. All periods of from 2 to 13 days were taken.

A curvilinear relationship between the difference of rainfall and drainage (deficit) and rainfall was established.

Residuals from this curve showed no appreciable correlation with the mean air temperature, but there was some slight evidence that the deficit was increased by a decrease in relative humidity or an increase in wind velocity.

The residuals showed little correlation with drainage during the previous 3 weeks.

An investigation of the problem of propinquity has shown that the yield of any unit of 6 in. of drill row of wheat is significantly affected by the number of plants in adjacent units. The “competition correlation”, which measures the intensity of this effect, is greatest with medium plant densities, and low and often insignificant for units of high or low plant density.

Competition is primarily underground for water, soil nutriments and soil air; of these, competition for water is most important in determining yield.

The discrepancies between nursery plots and field plots, found by previous workers when investigating yield problems with wheat, are discussed. The reason for these differences is given, and the true optimum plant density identified.

It is shown that the intensity of competition for water and soil nutriments influences the optimum plant density, and that a high intensity of competition is associated with a low optimum plant density. A summary of literature is given, and the varying values for the optimum seed rates in different parts of the world interpreted in the light of water and soil nutriment supplies.

1. In metabolism experiments undertaken to study the channels of elimination of copper under varying conditions, the rabbit was chosen as experimental animal for convenience of manipulation. This choice, although not defeating the main objects of the work, accidentally added valuable informationon the little-known habit of “physiological faecal refection”in this animal.

2. On a normal diet of bran and oats, containing the usual traces of copper, the rabbit is in copper equilibrium, excreting as much in faeces and urine as is taken in the food. Urinary elimination is of the order of 0·07–0·38 mg. per litre, but this is very subsidiary to faecal elimination of about 2·5 mg. per 100 g. of dry matter, which may account for even more than 96 % of the total food copper.

3. Increase of food copper is not reflected by material increase of urinary output, the higher quantities appearing almost entirely in the faeces. Of 50 mg. of copper or nearly 200 times the normal food intake, as the dissolved sulphate dried on to the food, only 0·1 mg. appeared in the urine, the remainder being slowly excreted in the faeces over the unexpectedly long period of 4 or 5 weeks.

Calcification on 1% of controlled cod-liver oil was less satisfactory than on 1% of genuine cod-liver oil as judged by radiography at 5 weeks old. Growth rates were not significantly different.

⅔ of 1% of the genuine cod-liver oil promoted calcification as satisfactorily as (and significantly better on one diet than) 1% of controlled oil. The mean tarso-metatarsal distances on ⅔ of 1% of controlled oil were too wide for the calcification to be regarded as normal. It has thus been shown that satisfactory growth is no criteria of adequate calcification and bone structure.

From the age of 6—16 weeks, ⅔ of 1% of controlled cod-liver oil mixture was not adequate, as demonstrated by radiographic examination, for optimal calcification; but using the criteria of naked eye examination and weight, no significant difference would have been found between genuine cod-liver oil and the controlled mixture. These birds showing subnormal calcification could not be expected to stand up well to the strain of laying, which puts heavy demands upon the calcium metabolism.