The Mashona cattle of Rhodesia are a strain of the Sanga type, which is found in specific areas of Central and Southern Africa. They are descended from protogenic Bos taurus, Bos indicus and Bos brachyceros cattle which were cross-bred in ancient times. in spite of the pandemics which ravaged herds at the turn of the last century, it seems that Mashona cattle have changed little since first brought to the country. An account is given of the Central African environment and the way it affects the physiological processes of cattle. Because Mashona cattle have lived in the Rhodesian environment for many centurites they are well adapted to it. A description is given of Mashona cattle which are being developed as a distinct breed in Rhodesia.

An attempt is made to investigate some techniques of experimentation, based on data from uniformity trials and experiments on tea conducted in different regions of north-east India. The study showed that:

1. i. Adjustment of yield due to covariance generally ceased to be efficient after the first four years of experimentation in manurial trials and after two years in pruning trials. Adjustment based on average yield over a period of four to six years resulted in an increase in efficiency.

2. ii. Among the ancillary variables of pretreatment yield and pruning weight, the former proved to be generally more efficient, but when cost of operation is taken into account the latter was economical and, therefore, preferable. The two variables together, in a multiple regression, did not show any extra gain. Use of the pretreatment late crop, from September to December, was generally more efficient than using the whole season's crop.

3. iii. Coefficient of variation showed a declining tendency with age, the fall being more marked up to six years of age. This suggests that, for a given degree of precision, more replication would be required for experiments with young tea than with mature tea.

4. iv. Increase in plot size, up to 48 bushes, resulted in an increase in information per replicate in Darjeeling, though plots of smaller size would be more economical.

5. v. On the basis of five uniformity trials in the Assam valley, Darjeeling and Cachar district, it was observed that for the same values of cost components proportional to number of replications and total area under experiment, the optimum plot size in Darjeeling and Cachar was about half that for the Assam valley.

6. vi. Long and narrow plots, oriented with their longer sides extending along the contour lines, within blocks of which the longer sides ran down the slope, proved more efficient than other alternatives in Darjeeling district.

7. vii. Systematic plucking of 1 in 2 out of the totality of plucking rounds, for experiments running for two or more years, provided estimates of treatment contrasts within 5 per cent of the population mean (P = 0-05). For a higher margin of error, of 10 per cent of the mean, systematic pluckings of 1 in 3 or even 1 in 4 would suffice if the treatment comparisons were based on five or more years.

A four-year study from 1958 to 1962 showed that time of application of fertilizer nitrogen greatly influenced the yield of grain, the percentage of nitrogen and the crude protein of the grain under Nigerian conditions characteristic of the early maize cropping season from March to July. Split applications of nitrogen fertilizer significantly increased maize grain yield by 35 per cent when two equal doses were given one month and two months after planting; and by 31 per cent when four equal doses were supplied at planting and one month, two months and three months after seeding. Yield was significantly reduced when application was delayed two months after planting. High yields of maize were not obtained by supplying the whole of nitrogen fertilizer at one time, eidier at sowing or any time later during the growing season. However, applying all of the nitrogen fertilizer one month after planting significantly increased the percentage of nitrogen and of the crude protein content of the grain. The maize ear weight was favourably influenced by spreading the nitrogen application over the three-month period of the maize growth.

A simple method of studying the reaction of detached cacao pods to Phytophthora palmivora is described. The results, which bear a close relation to field observations, are discussed in this context.

Digestibility of the palatable indigenous shrub Grewia carpinifolia was investigated. Digestion coefficients (%) were—organic matter 70, dry matter 70, crude protein 78, crude fibre 54, nitrogenfree extract 81, ether extract 13 and ash 52. Calculated nutritive values were—starch equivalent 27.3 and digestible crude protein 5.0, giving a nutritive ratio of about 1 : 5. The material used was moderately young.

The productivity of a herd of Mashona cattle is described, where hand-feeding was practised in winter to prevent loss of body weight. Calves weighed about 50 lb at birth, and gained weight at the rate of 1.27 lb a day to six months of age, compared widi 1.56 and 0.87 lb a day for calves at two other sites. Young animals gained an average of ½ lb a day from weaning to maturity. Mashona steers responded to pen-feeding and produced carcasses which were satisfactory for the Smithfield market. The mature weight of breeding cows was just under 700 lb and the calving rate varied from 72 to 92 per cent. Cows which failed to calve and those whose calves were early-weaned gained almost 100 lb liveweight by the end of die grazing season. Early-weaned calves fed a complete diet were 40 lb heavier than their contemporaries at 28 weeks of age. The need to develop die breed is discussed.

In connection with the processing of potatoes grown at Tarland, Aberdeenshire, certain field data were obtained over a period of eight years. It was found that the yield per acre was inversely correlated with rainfall and positively correlated with sunshine for the period May to September; the indications were that the period May to July was more important in this respect, high rainfall and low sunshine during this period depressing the crop more than high rainfall in the August to September period. It has been possible, statistically, to separate the effect of rainfall from that of sunshine (and temperature), and an analysis shows that sunshine (or temperature) is die dominant factor. The number of tubers produced was greatest in those years when sunshine was high and rainfall low. The dry matter content of die tubers was also highest when the sunshine was high and the rainfall low, the closest inverse correlation being with the rainfall for the month of August. The combination of high yield of potatoes and high dry matter content meant that the actual food produced was highest in the drier, more sunny, years.

The use of cultivation techniques to conserve rainfall, by preventing runoff, and to improve the soil surface infiltration rate, has produced spectacular increases in the yield of cotton on the Loess Plain soils of Northern Nigeria, where yields of the order of 2000 lb seed cotton per acre can now be produced regularly irrespective of the rainfall pattern. As yields of this level had not been obtained previously, it has been concluded that lack of soil moisture and poor soil aeration have in the past set a ceiling to seed cotton yields. The effects of these cultivation treatments on the two other major crops of the area, sorghum and groundnuts, have now been examined, and results from a series of field experiments over six seasons indicate that adequate soil moisture is essential to the production of high yields, but that the other soil conditions which are alleviated by these cultivations are not so critical for these two crops as they are for cotton. Reasons are suggested why spectacular increases in yield in response to the treatments are not generally to be expected with sorghum and groundnuts.

Scientific papers must be accurate and readable. Writers must deliberately arrange their information in a way that will interest and be useful to readers, and write clearly and directly, in the simplest possible English. There is no need for scientific writing to be ponderously overformal. Key features of style are short sentences, a minimum of jargon, use of familiar words, active rather than passive constructions, and personal, direct statements.