In Table XII is given a summary of the mean digestion coefficients obtained in the foregoing maize feeding experiments.

The figures in Table XII bring out very clearly the effect of preliminary treatment on the digestibility of maize. An inspection of the dry matter digestion coefficients reveals the fact that maize meal possesses the lowest digestibility when fed in the dry condition, a higher value when fed after thorough soaking in water and a higher value still when first submitted to cooking.

These facts are in accordance with anticipation; the surprising feature of the results, however, lies in the discovery of the inappreciable extent to which the maize digestibility is raised by soaking or cooking. A relatively low degree of digestibility might justifiably have been anticipated for raw unsoaked maize, since the hard flinty nature of the grain, even after crushing, might render it liable to be excreted in appreciable amount into the faeces without having been much affected by digestive enzymes. This proved by no means to be the case. The effect of thoroughly soaking the grain prior to feeding was merely to raise the digestibility of the maize by 1 per cent, (from 85·9 per cent, to 86·9 per cent.), whilst even efficient cooking only brought about a rise in digestibility from 85·9 to 88·1 per cent., although, as will be noted by reference to an earlier part of this communication, the conditions of the trial were weighted in favour of the cooked meal by using fine meal for cooking and crushed maize for dry-feeding.

1. Previous investigations showed that certain Scottish soils were of glacial drift origin, that they were comparatively rich in unweathered silicates and therefore in reserves of plant-food, that they showed considerable variation in such silicates and were capable of classification accordingly. Some indication was also shown that the glacial drift, and hence the resulting soil, was sometimes of local origin, its character being determined by the underlying rock. In the present investigation a more extensive survey of Scottish soils has been made in order to discover to what extent these preliminary findings might be applicable generally.

2. For this purpose soils have been collected from various localities in the north, north-east, west and south of Scotland, and have been analysed mechanically and the “fine sand” fraction examined mineralogically.

The secretions of the cervix are of interest because of the changes that occur in them during the oestrous cycle and during pregnancy. It is probable that these changes have an efEect in assisting or hindering the ascent of the spermatozoa to the Fallopian tubes after their deposition in the vagina.

(1) The cotton growing area in the Gezira consists of a heavy clay soil, the proportion of clay being about 50–60 per cent. in the upper layers with a maximum at about the 4th foot.

(2) The water soluble salts amount to about 0·2 per cent. The proportion is highest at about the 3rd to 5th foot. The alkalinity (pH) is highest at the 2nd foot.

(3) In the first 2 feet, the salts consist mainly of sodium carbonate and the third and fourth of sodium sulphate.

(4) The irrigation (Blue Nile) water is of excellent quality as judged by its natural chemical composition. The concentrated water, however, contains a very high proportion of alkali salts. It is estimated that a season of normal irrigation would cause an increase of 0·01 per cent. in the alkali content of the first 4 feet of soil.

(5) The sodium salts can readily act on the clay and the sodium clay so formed hydrolyses with the formation of sodium carbonate.

(6) Samples taken at the same time from good and bad plots in the same area show a strong correlation between salt content and cropyielding power. There is also a correlation between pH and fertility.

(7) In the same season and in the same area, virgin (i.e. unirrigated) plots give a higher yield than those which have been previously under the same system of cultivation.

1. Experiments in which were measured the resistances to (a) transverse breaking, (b) crushing, and (c) parting under tensile pull of standard blocks of soil prepared in different ways and under particular moisture conditions are described and discussed.

2. The soils examined comprised three highly colloidal siliceous soils containing amounts of calcium carbonate ranging from 7·2 to 0·2 percent., and two red lateritic soils.

3. The most significant results were obtained by employing, in a special tenacity apparatus, granular test-blocks, prepared by moistening sieve-graded dry soil packed into rectangular moulds. The results thus obtained are believed to furnish a reliable measure of the cohesiveness of soil colloidal matter, especially in soil blocks that have previously been brought to constant moisture content in a humidifier. The method of preparation simulates the effect of rain in causing the “running together” of colloidal soil particles.

4. The relative cohesiveness of the soils examined appears to follow the same order as their rates of settling from aqueous suspension. This observation strengthens the view that cohesiveness in colloidal soils is to a certain extent due to chemical forces that depend on the presence of active atoms or atomic groups possessing powerful fields of residual affinity, although probably film tension also plays a part.

With the aid of a careful technique a critical investigation has been made of the Hygroscopic Coefficient of soil at five temperatures, ranging from 15° C. to 35·6° C. It has been shown that (1) the customary 12–24 hours' period used by previous workers is much too short to give any approach to final values; (2) at the lower temperatures all except very light soils continue to take up water almost indefinitely, and it is not possible to extrapolate to an approximate final value; (3) these final values decrease with increasing temperature but in the early stages the rate of moisture absorption increases with increasing temperature; (4) the disputes as to whether the Hygroscopic Coefficient increased or decreased with temperature were due to the unrecognised operation of the effects detailed in (1) and (3) above.

In the foregoing communication on maize digestibility (i), reference has already been made to the early difficulties which arose as a consequence of attempting to make measurements on rations consisting wholly of maize and milk. During, the period in which a mixture of milk and flaked maize was being fed, the pigs developed constipation troubles, due, as subsequent results proved, to the almost complete digestion and assimilation of the ration by the animals. At the time, however, it was deemed expedient to alter somewhat the scheme of the experiment and to feed the maize along with a definite weight of coarse middlings. In this manner it was anticipated that the fibre of the coarse wheat offal would promote peristaltic activity in the intestinal tract and thus assist the passage of undigested food residues.

The introduction of the middlings into the experimental ration made necessary the determination of the digestibility of this feeding stuff. The results of this trial are given for convenience in this separate communication.

The agricultural conception, yield, piquantly clear to farmers, has evaded statistical analysis and confounded plant physiology. It may be defined for cereals as the average weight of grain produced per unit area. Grain is an end-product of the operation throughout the plant's life, of all its vital processes. Yield therefore, in some complex way, must reflect the working of these processes. An analysis of yield would simplify the testing of new plant forms and regularise the selection of parents in hybridising. Fundamentally this analysis should comprise the identification of the vital processes of the plant, the effects upon them of environmental factors, and their relationship to grain production. At present even to speculate upon the making of such an analysis would be mere pedantry. Nothing but an algebraic analysis is practicable.

A study has been made of the intensity of the forces binding soil particles together, when the soil has been previously subjected to treatments simulating various field conditions, and certain laboratory processes connected with physical, chemical and biological investigations.

The technique adopted consisted in shaking soil with water under reproducible conditions, allowing the mixture to stand for 24 hours, and then determining the concentration of soil in the top 8·5 cm. of the suspension. This concentration was expressed as a percentage of the original concentration of the soil, and the value thus obtained was called the dispersion factor of the soil under the given conditions of treatment.

1. Of 583 pig foetuses of all ages, 331 were found to be males and 252 females, giving a male percentage of 56·8, which is much higher than the approximate equality between the sexes that seems to exist at birth. This result confirms Jewell, who found a male percentage of 55 among 1000 cow foetuses.

2. These 583 pig foetuses when classified by weight (0–100 gm., 101–300 gm., 301+gm.) gave the following percentages of males for the respective groups, 59·1, 57·0, 53·2. In other words, the percentage of males decreases as gestation proceeds, a result which can only be brought about by a differential mortality of males and females. It would appear that the percentage at conception must be very near 60 per cent. or 150 males per 100 females.

3. The sex-ratios of foetuses from the left and right cornua show no significant difference, 55·0 for the right and 54·7 for the left.

4. The males were found to average about 7 per cent. heavier than the females.

5. There seems to be an inverse correlation between the number of foetuses in a horn and their average weight. Foetuses from the left cornu have a slightly greater weight than those from the right, and this may be connected with the slightly inferior fertility of this horn.

6. The excess of males at conception is discussed in the light of the implications of the chromosome mechanism of sex determination, and reference is made to the greater mortality of the males.

(1) The results of experiments on the rate of horizontal flow, and on the rate of gain in mass, or kerosene and of water in fine and crumb fractions of certain West Indian colloidal soils, comprising three siliceous soils containing different amounts of calcium carbonate, and two lateritic soils, are described and tabulated.

(2) The methods of experimentation employed were those elaborated by Green and Ampt, whose equations were found, however, not to fit the values obtained, as is to be expected.

(3) The siliceous soils examined possess relatively high swelling coefficients, and their component particles, when wetted, cohere to a greater or lesser extent, depending on lime content. These properties appear to account for the relatively low rates of permeability to water in these soils. Lateritic soils, on the other hand, possess low swelling coefficients, and low cohesiveness; water percolates through them relatively very rapidly.

During the investigation in connection with maize digestibility recorded in the current issue of this journal (1), a period of feeding was carried out in which the two pigs received a ration consisting of unsoaked crushed maize and whole milk. Although it was found necessary to discontinue the main maize trial along these lines, the results of this isolated period are not without interest, since they enable conclusions to be drawn concerning the extent of the digestion and assimilation of the constituents of milk when fed to swine.

The crushed maize used in this period was from the same stock as that fed in the mixed maize and middlings periods. The daily ration consisted of 2000 gm. crushed maize together with one quart of whole milk; it was given in two equal portions during the day, the milk and a little water being mixed with the dry maize in the trough at the time of feeding. The presence of the milk appeared to make the ration attractive to the animals, since ready and complete consumption was obtained.

In the course of an investigation on the nitrification process in soils a series of pot experiments was set up to compare the manurial actions of some typical organic nitrogen compounds. The laboratory work was interrupted at an early stage; the results of the pot experiments are briefly described in this note.

Canada's western prairies, lying within the confines of the provinces of Manitoba, Saskatchewan and Alberta, are generally recognised as comprising one of the largest and most important agricultural areas on the American continent. The immense acreage of their arable lands, the great depth and high fertility of their soils and the unexcelled quality of their wheat, have made them widely and favourably known throughout the civilised world. As yet but sparsely settled they will for many years offer a large and attractive field for agricultural occupation and development.

An account has been given of an investigation into the changes which occur during the preservation of the oat and tare crop in the clamp silo.

The material obtained from the clamp was divisible into three types: (1) An uppermost thick layer of mouldy material. (2) “Sweet” silage from the middle layers. (3) Wet “sour” silage from the bottom layer. The spoilt material in the top layer represented approximately 19 per cent. of the whole of the crop contained in the clamp, and in addition to this, the silage was extensively spoilt round the sides of the clamp to an average depth of 12 inches. In comparing the processes of ensilage in the tower and in the clamp, it should be remembered that spoiling of this type only affects the top few inches of the material in the tower silo.

The loss of dry matter in the “sour” silage layer, arising from fermentation and drainage away of juice, amounted to more than one-fifth of the dry matter of the crop originally present in the layer. This represents a much bigger loss than any previously recorded at Cambridge in similar work with tower silos. An exceptionally heavy destruction of carbohydrates further characterised the production of the “sour” silage in the clamp.

The loss of dry matter in the “sweet” silage layer was much smaller and was comparable in magnitude with that occurring during the production of “green fruity” silage in tower silos.

The chemical characteristics of the “sour” silage samples were investigated and were found to conform with results discussed in a previous communication, namely, the samples contained a high proportion of volatile bases to amino acids, and the volatile acids were present in appreciable excess of the non-volatile organic acids.

(1) Hydrogen peroxide oxidises or renders soluble a portion of the organic matter of soils. It appears to be without action on fibrous organic substances such as cellulose and lignins. Humified material seems to be oxidised completely or brought into a water soluble state.

(2) Treatment with hydrogen peroxide is proposed as the basis of a method for estimating the approximate degree of humification of soil organic matter.

(3) Among the soils examined, the highest degree of humification is found in peats and uncultivated soils. It is possible that the degree of humification is correlated with the prevalence of anaerobic conditions.

(1) Rather over 50 per cent, of the cows in this country probably possess accessory or supernumerary teats, the number of which varies from one to three.

(2) In many cases at any rate, these teats are associated with additional glands.

(3) These additional glands are frequently functional and secrete milk.

(4) Ordinarily this milk is absorbed into the circulation, the lactose being secreted in the urine.

(5) The presence of active accessory or supernumerary glands is an undesirable characteristic since it involves the formation of milk which is not utilised.

The removal of soluble humus by alkaline extraction from both a garden and a field soil reduced the productiveness over a series of crops in pot experiments. The field soil showed an initial but temporary increase in productiveness.

In determining the nitrogen content of the heavy black cotton soil of the Central Provinces, India, by the Kjeldahl process it is important that the determinations be carried out on moist and not on air-dried soil. These soils apparently contain a cementing material probably containing iron which is insoluble in concentrated sulphuric acid and protects organic matter in the interior of the compound particles from the action of the acid.

It may be that these soils are peculiar in this respect, but it would seem of importance that other workers should take into account the possibility of error in the estimation of nitrogen when using air-dry soils.

In conclusion it is with great pleasure that I acknowledge my indebtedness to Mr F. J. Plymen and Dr H. E. Annett for their valuable suggestions and advice during the course of this work.

The mechanical properties of soils which are concerned in ploughing are considered under the three heads:

(1) Soil cohesion.

(2) Soil plasticity.

(3) Surface friction between soil and metal.

In each case methods of measurements are discussed and experimental curves are given for representative soils over the whole moisture range with which the practical agriculturist is concerned.

In the case of cohesion Atterberg's method of measurement is followed. A certain difference in character between his results and the author's is discussed.

A new technique is described for measuring one of the plastic constants, which is specially adapted to clays, and throws fresh light on their physical characteristics.

The measurements on soil friction open up a fresh subject, and promise to provide a sensitive means of investigating soil-water relationships from a new angle.